pgtype uses pgxtest

Added ValueRoundTripTest to pgxtest
Removed pgtype/testutil

pgtype tests now run with all (applicable) query modes. This gives
better coverage than before and revealed several bugs which are also
fixed in this commit.

conn.go

@@ -558,18 +558,41 @@ func (c *Conn) execSQLParams(ctx context.Context, sql string, args []interface{}
 // Given that the whole point of QueryExecModeExec is to operate without having to know the PostgreSQL types there is
 // no way to safely use binary or to specify the parameter OIDs.
 func (c *Conn) appendParamsForQueryExecModeExec(args []interface{}) error {
-	for i := range args {
+	for _, arg := range args {
-		if args[i] == nil {
+		if arg == nil {
-			err := c.eqb.AppendParamFormat(c.typeMap, 0, TextFormatCode, args[i])
+			err := c.eqb.AppendParamFormat(c.typeMap, 0, TextFormatCode, arg)
 			if err != nil {
 				return err
 			}
 		} else {
-			dt, ok := c.TypeMap().TypeForValue(args[i])
+			dt, ok := c.TypeMap().TypeForValue(arg)
 			if !ok {
-				return &unknownArgumentTypeQueryExecModeExecError{arg: args[i]}
+				var tv pgtype.TextValuer
+				if tv, ok = arg.(pgtype.TextValuer); ok {
+					t, err := tv.TextValue()
+					if err != nil {
+						return err
 					}
-			err := c.eqb.AppendParamFormat(c.typeMap, dt.OID, TextFormatCode, args[i])
+
+					dt, ok = c.TypeMap().TypeForOID(pgtype.TextOID)
+					if ok {
+						arg = t
+					}
+				}
+			}
+			if !ok {
+				var str fmt.Stringer
+				if str, ok = arg.(fmt.Stringer); ok {
+					dt, ok = c.TypeMap().TypeForOID(pgtype.TextOID)
+					if ok {
+						arg = str.String()
+					}
+				}
+			}
+			if !ok {
+				return &unknownArgumentTypeQueryExecModeExecError{arg: arg}
+			}
+			err := c.eqb.AppendParamFormat(c.typeMap, dt.OID, TextFormatCode, arg)
 			if err != nil {
 				return err
 			}

pgtype/array_codec_test.go

@@ -4,15 +4,13 @@ import (
 	"context"
 	"testing"
 
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	pgx "github.com/jackc/pgx/v5"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
 func TestArrayCodec(t *testing.T) {
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
-
 		for i, tt := range []struct {
 			expected interface{}
 		}{
@@ -22,7 +20,7 @@ func TestArrayCodec(t *testing.T) {
 		} {
 			var actual []int16
 			err := conn.QueryRow(
-			context.Background(),
+				ctx,
 				"select $1::smallint[]",
 				tt.expected,
 			).Scan(&actual)
@@ -39,19 +37,18 @@ func TestArrayCodec(t *testing.T) {
 		} {
 			var actual []*int16
 			err := conn.QueryRow(
-			context.Background(),
+				ctx,
 				"select $1::smallint[]",
 				tt.expected,
 			).Scan(&actual)
 			assert.NoErrorf(t, err, "%d", i)
 			assert.Equalf(t, tt.expected, actual, "%d", i)
 		}
+	})
 }
 
 func TestArrayCodecAnySlice(t *testing.T) {
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
-
 		type _int16Slice []int16
 
 		for i, tt := range []struct {
@@ -63,19 +60,18 @@ func TestArrayCodecAnySlice(t *testing.T) {
 		} {
 			var actual _int16Slice
 			err := conn.QueryRow(
-			context.Background(),
+				ctx,
 				"select $1::smallint[]",
 				tt.expected,
 			).Scan(&actual)
 			assert.NoErrorf(t, err, "%d", i)
 			assert.Equalf(t, tt.expected, actual, "%d", i)
 		}
+	})
 }
 
 func TestArrayCodecDecodeValue(t *testing.T) {
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, _ testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
-
 		for _, tt := range []struct {
 			sql      string
 			expected interface{}
@@ -94,7 +90,7 @@ func TestArrayCodecDecodeValue(t *testing.T) {
 			},
 		} {
 			t.Run(tt.sql, func(t *testing.T) {
-			rows, err := conn.Query(context.Background(), tt.sql)
+				rows, err := conn.Query(ctx, tt.sql)
 				require.NoError(t, err)
 
 				for rows.Next() {
@@ -107,15 +103,15 @@ func TestArrayCodecDecodeValue(t *testing.T) {
 				require.NoError(t, rows.Err())
 			})
 		}
+	})
 }
 
 func TestArrayCodecScanMultipleDimensions(t *testing.T) {
 	skipCockroachDB(t, "Server does not support nested arrays (https://github.com/cockroachdb/cockroach/issues/36815)")
 
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
 
-	rows, err := conn.Query(context.Background(), `select '{{1,2,3,4}, {5,6,7,8}, {9,10,11,12}}'::int4[]`)
+		rows, err := conn.Query(ctx, `select '{{1,2,3,4}, {5,6,7,8}, {9,10,11,12}}'::int4[]`)
 		require.NoError(t, err)
 
 		for rows.Next() {
@@ -126,15 +122,14 @@ func TestArrayCodecScanMultipleDimensions(t *testing.T) {
 		}
 
 		require.NoError(t, rows.Err())
+	})
 }
 
 func TestArrayCodecScanMultipleDimensionsEmpty(t *testing.T) {
 	skipCockroachDB(t, "Server does not support nested arrays (https://github.com/cockroachdb/cockroach/issues/36815)")
 
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
+		rows, err := conn.Query(ctx, `select '{}'::int4[]`)
-
-	rows, err := conn.Query(context.Background(), `select '{}'::int4[]`)
 		require.NoError(t, err)
 
 		for rows.Next() {
@@ -145,15 +140,14 @@ func TestArrayCodecScanMultipleDimensionsEmpty(t *testing.T) {
 		}
 
 		require.NoError(t, rows.Err())
+	})
 }
 
 func TestArrayCodecScanWrongMultipleDimensions(t *testing.T) {
 	skipCockroachDB(t, "Server does not support nested arrays (https://github.com/cockroachdb/cockroach/issues/36815)")
 
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
+		rows, err := conn.Query(ctx, `select '{{1,2,3,4}, {5,6,7,8}, {9,10,11,12}}'::int4[]`)
-
-	rows, err := conn.Query(context.Background(), `select '{{1,2,3,4}, {5,6,7,8}, {9,10,11,12}}'::int4[]`)
 		require.NoError(t, err)
 
 		for rows.Next() {
@@ -161,15 +155,14 @@ func TestArrayCodecScanWrongMultipleDimensions(t *testing.T) {
 			err := rows.Scan(&ss)
 			require.Error(t, err, "can't scan into dest[0]: PostgreSQL array has 2 dimensions but slice has 3 dimensions")
 		}
+	})
 }
 
 func TestArrayCodecEncodeMultipleDimensions(t *testing.T) {
 	skipCockroachDB(t, "Server does not support nested arrays (https://github.com/cockroachdb/cockroach/issues/36815)")
 
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
+		rows, err := conn.Query(ctx, `select $1::int4[]`, [][]int32{{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}})
-
-	rows, err := conn.Query(context.Background(), `select $1::int4[]`, [][]int32{{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}})
 		require.NoError(t, err)
 
 		for rows.Next() {
@@ -180,15 +173,15 @@ func TestArrayCodecEncodeMultipleDimensions(t *testing.T) {
 		}
 
 		require.NoError(t, rows.Err())
+	})
 }
 
 func TestArrayCodecEncodeMultipleDimensionsRagged(t *testing.T) {
 	skipCockroachDB(t, "Server does not support nested arrays (https://github.com/cockroachdb/cockroach/issues/36815)")
 
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
+		rows, err := conn.Query(ctx, `select $1::int4[]`, [][]int32{{1, 2, 3, 4}, {5}, {9, 10, 11, 12}})
-
-	rows, err := conn.Query(context.Background(), `select $1::int4[]`, [][]int32{{1, 2, 3, 4}, {5}, {9, 10, 11, 12}})
 		require.Error(t, err, "cannot convert [][]int32 to ArrayGetter because it is a ragged multi-dimensional")
 		defer rows.Close()
+	})
 }

pgtype/bits_test.go

@@ -2,10 +2,11 @@ package pgtype_test
 
 import (
 	"bytes"
+	"context"
 	"testing"
 
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func isExpectedEqBits(a interface{}) func(interface{}) bool {
@@ -17,7 +18,7 @@ func isExpectedEqBits(a interface{}) func(interface{}) bool {
 }
 
 func TestBitsCodecBit(t *testing.T) {
-	testutil.RunTranscodeTests(t, "bit(40)", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "bit(40)", []pgxtest.ValueRoundTripTest{
 		{
 			pgtype.Bits{Bytes: []byte{0, 0, 0, 0, 0}, Len: 40, Valid: true},
 			new(pgtype.Bits),
@@ -34,7 +35,7 @@ func TestBitsCodecBit(t *testing.T) {
 }
 
 func TestBitsCodecVarbit(t *testing.T) {
-	testutil.RunTranscodeTests(t, "varbit", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "varbit", []pgxtest.ValueRoundTripTest{
 		{
 			pgtype.Bits{Bytes: []byte{}, Len: 0, Valid: true},
 			new(pgtype.Bits),

pgtype/bool_test.go

@@ -1,14 +1,15 @@
 package pgtype_test
 
 import (
+	"context"
 	"testing"
 
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func TestBoolCodec(t *testing.T) {
-	testutil.RunTranscodeTests(t, "bool", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "bool", []pgxtest.ValueRoundTripTest{
 		{true, new(bool), isExpectedEq(true)},
 		{false, new(bool), isExpectedEq(false)},
 		{true, new(pgtype.Bool), isExpectedEq(pgtype.Bool{Bool: true, Valid: true})},

pgtype/box_test.go

@@ -1,16 +1,17 @@
 package pgtype_test
 
 import (
+	"context"
 	"testing"
 
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func TestBoxCodec(t *testing.T) {
 	skipCockroachDB(t, "Server does not support box type")
 
-	testutil.RunTranscodeTests(t, "box", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "box", []pgxtest.ValueRoundTripTest{
 		{
 			pgtype.Box{
 				P:     [2]pgtype.Vec2{{7.1, 5.2345678}, {3.14, 1.678}},

pgtype/bytea_test.go

@@ -5,8 +5,9 @@ import (
 	"context"
 	"testing"
 
+	pgx "github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 	"github.com/stretchr/testify/require"
 )
 
@@ -28,7 +29,7 @@ func isExpectedEqBytes(a interface{}) func(interface{}) bool {
 }
 
 func TestByteaCodec(t *testing.T) {
-	testutil.RunTranscodeTests(t, "bytea", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "bytea", []pgxtest.ValueRoundTripTest{
 		{[]byte{1, 2, 3}, new([]byte), isExpectedEqBytes([]byte{1, 2, 3})},
 		{[]byte{}, new([]byte), isExpectedEqBytes([]byte{})},
 		{[]byte(nil), new([]byte), isExpectedEqBytes([]byte(nil))},
@@ -37,22 +38,15 @@ func TestByteaCodec(t *testing.T) {
 }
 
 func TestDriverBytesQueryRow(t *testing.T) {
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
-
-	ctx := context.Background()
-
 		var buf []byte
 		err := conn.QueryRow(ctx, `select $1::bytea`, []byte{1, 2}).Scan((*pgtype.DriverBytes)(&buf))
 		require.EqualError(t, err, "cannot scan into *pgtype.DriverBytes from QueryRow")
+	})
 }
 
 func TestDriverBytes(t *testing.T) {
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
-
-	ctx := context.Background()
-
 		argBuf := make([]byte, 128)
 		for i := range argBuf {
 			argBuf[i] = byte(i)
@@ -85,14 +79,11 @@ func TestDriverBytes(t *testing.T) {
 
 		err = rows.Err()
 		require.NoError(t, err)
+	})
 }
 
 func TestPreallocBytes(t *testing.T) {
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
-
-	ctx := context.Background()
-
 		origBuf := []byte{5, 6, 7, 8}
 		buf := origBuf
 		err := conn.QueryRow(ctx, `select $1::bytea`, []byte{1, 2}).Scan((*pgtype.PreallocBytes)(&buf))
@@ -110,18 +101,16 @@ func TestPreallocBytes(t *testing.T) {
 		require.Equal(t, 5, cap(buf))
 
 		require.Equal(t, []byte{1, 2, 7, 8}, origBuf)
+	})
 }
 
 func TestUndecodedBytes(t *testing.T) {
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
-
-	ctx := context.Background()
-
 		var buf []byte
 		err := conn.QueryRow(ctx, `select 1::int4`).Scan((*pgtype.UndecodedBytes)(&buf))
 		require.NoError(t, err)
 
 		require.Len(t, buf, 4)
 		require.Equal(t, buf, []byte{0, 0, 0, 1})
+	})
 }

pgtype/circle_test.go

@@ -1,16 +1,17 @@
 package pgtype_test
 
 import (
+	"context"
 	"testing"
 
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func TestCircleTranscode(t *testing.T) {
 	skipCockroachDB(t, "Server does not support box type")
 
-	testutil.RunTranscodeTests(t, "circle", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "circle", []pgxtest.ValueRoundTripTest{
 		{
 			pgtype.Circle{P: pgtype.Vec2{1.234, 5.67890123}, R: 3.5, Valid: true},
 			new(pgtype.Circle),

pgtype/composite_test.go

@@ -7,26 +7,24 @@ import (
 
 	pgx "github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
 	"github.com/stretchr/testify/require"
 )
 
 func TestCompositeCodecTranscode(t *testing.T) {
 	skipCockroachDB(t, "Server does not support composite types (see https://github.com/cockroachdb/cockroach/issues/27792)")
 
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
 
-	_, err := conn.Exec(context.Background(), `drop type if exists ct_test;
+		_, err := conn.Exec(ctx, `drop type if exists ct_test;
 
 create type ct_test as (
 	a text,
   b int4
 );`)
 		require.NoError(t, err)
-	defer conn.Exec(context.Background(), "drop type ct_test")
+		defer conn.Exec(ctx, "drop type ct_test")
 
-	dt, err := conn.LoadType(context.Background(), "ct_test")
+		dt, err := conn.LoadType(ctx, "ct_test")
 		require.NoError(t, err)
 		conn.TypeMap().RegisterType(dt)
 
@@ -42,7 +40,7 @@ create type ct_test as (
 			var a string
 			var b int32
 
-		err := conn.QueryRow(context.Background(), "select $1::ct_test", pgx.QueryResultFormats{format.code},
+			err := conn.QueryRow(ctx, "select $1::ct_test", pgx.QueryResultFormats{format.code},
 				pgtype.CompositeFields{"hi", int32(42)},
 			).Scan(
 				pgtype.CompositeFields{&a, &b},
@@ -51,6 +49,7 @@ create type ct_test as (
 			require.EqualValuesf(t, "hi", a, "%v", format.name)
 			require.EqualValuesf(t, 42, b, "%v", format.name)
 		}
+	})
 }
 
 type point3d struct {
@@ -94,10 +93,9 @@ func (p *point3d) ScanIndex(i int) interface{} {
 func TestCompositeCodecTranscodeStruct(t *testing.T) {
 	skipCockroachDB(t, "Server does not support composite types (see https://github.com/cockroachdb/cockroach/issues/27792)")
 
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
 
-	_, err := conn.Exec(context.Background(), `drop type if exists point3d;
+		_, err := conn.Exec(ctx, `drop type if exists point3d;
 
 create type point3d as (
 	x float8,
@@ -105,9 +103,9 @@ create type point3d as (
 	z float8
 );`)
 		require.NoError(t, err)
-	defer conn.Exec(context.Background(), "drop type point3d")
+		defer conn.Exec(ctx, "drop type point3d")
 
-	dt, err := conn.LoadType(context.Background(), "point3d")
+		dt, err := conn.LoadType(ctx, "point3d")
 		require.NoError(t, err)
 		conn.TypeMap().RegisterType(dt)
 
@@ -122,19 +120,19 @@ create type point3d as (
 		for _, format := range formats {
 			input := point3d{X: 1, Y: 2, Z: 3}
 			var output point3d
-		err := conn.QueryRow(context.Background(), "select $1::point3d", pgx.QueryResultFormats{format.code}, input).Scan(&output)
+			err := conn.QueryRow(ctx, "select $1::point3d", pgx.QueryResultFormats{format.code}, input).Scan(&output)
 			require.NoErrorf(t, err, "%v", format.name)
 			require.Equalf(t, input, output, "%v", format.name)
 		}
+	})
 }
 
 func TestCompositeCodecTranscodeStructWrapper(t *testing.T) {
 	skipCockroachDB(t, "Server does not support composite types (see https://github.com/cockroachdb/cockroach/issues/27792)")
 
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
 
-	_, err := conn.Exec(context.Background(), `drop type if exists point3d;
+		_, err := conn.Exec(ctx, `drop type if exists point3d;
 
 create type point3d as (
 	x float8,
@@ -142,9 +140,9 @@ create type point3d as (
 	z float8
 );`)
 		require.NoError(t, err)
-	defer conn.Exec(context.Background(), "drop type point3d")
+		defer conn.Exec(ctx, "drop type point3d")
 
-	dt, err := conn.LoadType(context.Background(), "point3d")
+		dt, err := conn.LoadType(ctx, "point3d")
 		require.NoError(t, err)
 		conn.TypeMap().RegisterType(dt)
 
@@ -163,19 +161,19 @@ create type point3d as (
 		for _, format := range formats {
 			input := anotherPoint{X: 1, Y: 2, Z: 3}
 			var output anotherPoint
-		err := conn.QueryRow(context.Background(), "select $1::point3d", pgx.QueryResultFormats{format.code}, input).Scan(&output)
+			err := conn.QueryRow(ctx, "select $1::point3d", pgx.QueryResultFormats{format.code}, input).Scan(&output)
 			require.NoErrorf(t, err, "%v", format.name)
 			require.Equalf(t, input, output, "%v", format.name)
 		}
+	})
 }
 
 func TestCompositeCodecDecodeValue(t *testing.T) {
 	skipCockroachDB(t, "Server does not support composite types (see https://github.com/cockroachdb/cockroach/issues/27792)")
 
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
 
-	_, err := conn.Exec(context.Background(), `drop type if exists point3d;
+		_, err := conn.Exec(ctx, `drop type if exists point3d;
 
 create type point3d as (
 	x float8,
@@ -183,9 +181,9 @@ create type point3d as (
 	z float8
 );`)
 		require.NoError(t, err)
-	defer conn.Exec(context.Background(), "drop type point3d")
+		defer conn.Exec(ctx, "drop type point3d")
 
-	dt, err := conn.LoadType(context.Background(), "point3d")
+		dt, err := conn.LoadType(ctx, "point3d")
 		require.NoError(t, err)
 		conn.TypeMap().RegisterType(dt)
 
@@ -198,7 +196,7 @@ create type point3d as (
 		}
 
 		for _, format := range formats {
-		rows, err := conn.Query(context.Background(), "select '(1,2,3)'::point3d", pgx.QueryResultFormats{format.code})
+			rows, err := conn.Query(ctx, "select '(1,2,3)'::point3d", pgx.QueryResultFormats{format.code})
 			require.NoErrorf(t, err, "%v", format.name)
 			require.True(t, rows.Next())
 			values, err := rows.Values()
@@ -208,4 +206,5 @@ create type point3d as (
 			require.False(t, rows.Next())
 			require.NoErrorf(t, rows.Err(), "%v", format.name)
 		}
+	})
 }

pgtype/date_test.go

@@ -1,11 +1,12 @@
 package pgtype_test
 
 import (
+	"context"
 	"testing"
 	"time"
 
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func isExpectedEqTime(a interface{}) func(interface{}) bool {
@@ -18,7 +19,7 @@ func isExpectedEqTime(a interface{}) func(interface{}) bool {
 }
 
 func TestDateCodec(t *testing.T) {
-	testutil.RunTranscodeTests(t, "date", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "date", []pgxtest.ValueRoundTripTest{
 		{time.Date(-100, 1, 1, 0, 0, 0, 0, time.UTC), new(time.Time), isExpectedEqTime(time.Date(-100, 1, 1, 0, 0, 0, 0, time.UTC))},
 		{time.Date(-1, 1, 1, 0, 0, 0, 0, time.UTC), new(time.Time), isExpectedEqTime(time.Date(-1, 1, 1, 0, 0, 0, 0, time.UTC))},
 		{time.Date(0, 1, 1, 0, 0, 0, 0, time.UTC), new(time.Time), isExpectedEqTime(time.Date(0, 1, 1, 0, 0, 0, 0, time.UTC))},

pgtype/enum_codec_test.go

@@ -4,66 +4,66 @@ import (
 	"context"
 	"testing"
 
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	pgx "github.com/jackc/pgx/v5"
 	"github.com/stretchr/testify/require"
 )
 
 func TestEnumCodec(t *testing.T) {
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
 
-	_, err := conn.Exec(context.Background(), `drop type if exists enum_test;
+		_, err := conn.Exec(ctx, `drop type if exists enum_test;
 
 create type enum_test as enum ('foo', 'bar', 'baz');`)
 		require.NoError(t, err)
-	defer conn.Exec(context.Background(), "drop type enum_test")
+		defer conn.Exec(ctx, "drop type enum_test")
 
-	dt, err := conn.LoadType(context.Background(), "enum_test")
+		dt, err := conn.LoadType(ctx, "enum_test")
 		require.NoError(t, err)
 
 		conn.TypeMap().RegisterType(dt)
 
 		var s string
-	err = conn.QueryRow(context.Background(), `select 'foo'::enum_test`).Scan(&s)
+		err = conn.QueryRow(ctx, `select 'foo'::enum_test`).Scan(&s)
 		require.NoError(t, err)
 		require.Equal(t, "foo", s)
 
-	err = conn.QueryRow(context.Background(), `select $1::enum_test`, "bar").Scan(&s)
+		err = conn.QueryRow(ctx, `select $1::enum_test`, "bar").Scan(&s)
 		require.NoError(t, err)
 		require.Equal(t, "bar", s)
 
-	err = conn.QueryRow(context.Background(), `select 'foo'::enum_test`).Scan(&s)
+		err = conn.QueryRow(ctx, `select 'foo'::enum_test`).Scan(&s)
 		require.NoError(t, err)
 		require.Equal(t, "foo", s)
 
-	err = conn.QueryRow(context.Background(), `select $1::enum_test`, "bar").Scan(&s)
+		err = conn.QueryRow(ctx, `select $1::enum_test`, "bar").Scan(&s)
 		require.NoError(t, err)
 		require.Equal(t, "bar", s)
 
-	err = conn.QueryRow(context.Background(), `select 'baz'::enum_test`).Scan(&s)
+		err = conn.QueryRow(ctx, `select 'baz'::enum_test`).Scan(&s)
 		require.NoError(t, err)
 		require.Equal(t, "baz", s)
+	})
 }
 
 func TestEnumCodecValues(t *testing.T) {
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
 
-	_, err := conn.Exec(context.Background(), `drop type if exists enum_test;
+		_, err := conn.Exec(ctx, `drop type if exists enum_test;
 
 create type enum_test as enum ('foo', 'bar', 'baz');`)
 		require.NoError(t, err)
-	defer conn.Exec(context.Background(), "drop type enum_test")
+		defer conn.Exec(ctx, "drop type enum_test")
 
-	dt, err := conn.LoadType(context.Background(), "enum_test")
+		dt, err := conn.LoadType(ctx, "enum_test")
 		require.NoError(t, err)
 
 		conn.TypeMap().RegisterType(dt)
 
-	rows, err := conn.Query(context.Background(), `select 'foo'::enum_test`)
+		rows, err := conn.Query(ctx, `select 'foo'::enum_test`)
 		require.NoError(t, err)
 		require.True(t, rows.Next())
 		values, err := rows.Values()
 		require.NoError(t, err)
 		require.Equal(t, values, []interface{}{"foo"})
+	})
 }

pgtype/float4_test.go

@@ -1,14 +1,15 @@
 package pgtype_test
 
 import (
+	"context"
 	"testing"
 
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func TestFloat4Codec(t *testing.T) {
-	testutil.RunTranscodeTests(t, "float4", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "float4", []pgxtest.ValueRoundTripTest{
 		{pgtype.Float4{Float32: -1, Valid: true}, new(pgtype.Float4), isExpectedEq(pgtype.Float4{Float32: -1, Valid: true})},
 		{pgtype.Float4{Float32: 0, Valid: true}, new(pgtype.Float4), isExpectedEq(pgtype.Float4{Float32: 0, Valid: true})},
 		{pgtype.Float4{Float32: 1, Valid: true}, new(pgtype.Float4), isExpectedEq(pgtype.Float4{Float32: 1, Valid: true})},

pgtype/float8_test.go

@@ -1,14 +1,15 @@
 package pgtype_test
 
 import (
+	"context"
 	"testing"
 
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func TestFloat8Codec(t *testing.T) {
-	testutil.RunTranscodeTests(t, "float8", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "float8", []pgxtest.ValueRoundTripTest{
 		{pgtype.Float8{Float64: -1, Valid: true}, new(pgtype.Float8), isExpectedEq(pgtype.Float8{Float64: -1, Valid: true})},
 		{pgtype.Float8{Float64: 0, Valid: true}, new(pgtype.Float8), isExpectedEq(pgtype.Float8{Float64: 0, Valid: true})},
 		{pgtype.Float8{Float64: 1, Valid: true}, new(pgtype.Float8), isExpectedEq(pgtype.Float8{Float64: 1, Valid: true})},

pgtype/hstore_test.go

@@ -6,7 +6,7 @@ import (
 
 	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func isExpectedEqMapStringString(a interface{}) func(interface{}) bool {
@@ -52,9 +52,8 @@ func isExpectedEqMapStringPointerString(a interface{}) func(interface{}) bool {
 }
 
 func TestHstoreCodec(t *testing.T) {
-	conn := testutil.MustConnectPgx(t)
+	ctr := defaultConnTestRunner
-	defer testutil.MustCloseContext(t, conn)
+	ctr.AfterConnect = func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-
 		var hstoreOID uint32
 		err := conn.QueryRow(context.Background(), `select oid from pg_type where typname = 'hstore'`).Scan(&hstoreOID)
 		if err != nil {
@@ -62,20 +61,13 @@ func TestHstoreCodec(t *testing.T) {
 		}
 
 		conn.TypeMap().RegisterType(&pgtype.Type{Name: "hstore", OID: hstoreOID, Codec: pgtype.HstoreCodec{}})
-
-	formats := []struct {
-		name string
-		code int16
-	}{
-		{name: "TextFormat", code: pgx.TextFormatCode},
-		{name: "BinaryFormat", code: pgx.BinaryFormatCode},
 	}
 
 	fs := func(s string) *string {
 		return &s
 	}
 
-	tests := []testutil.TranscodeTestCase{
+	tests := []pgxtest.ValueRoundTripTest{
 		{
 			map[string]string{},
 			new(map[string]string),
@@ -134,25 +126,25 @@ func TestHstoreCodec(t *testing.T) {
 		// Special key values
 
 		// at beginning
-		tests = append(tests, testutil.TranscodeTestCase{
+		tests = append(tests, pgxtest.ValueRoundTripTest{
 			map[string]string{s + "foo": "bar"},
 			new(map[string]string),
 			isExpectedEqMapStringString(map[string]string{s + "foo": "bar"}),
 		})
 		// in middle
-		tests = append(tests, testutil.TranscodeTestCase{
+		tests = append(tests, pgxtest.ValueRoundTripTest{
 			map[string]string{"foo" + s + "bar": "bar"},
 			new(map[string]string),
 			isExpectedEqMapStringString(map[string]string{"foo" + s + "bar": "bar"}),
 		})
 		// at end
-		tests = append(tests, testutil.TranscodeTestCase{
+		tests = append(tests, pgxtest.ValueRoundTripTest{
 			map[string]string{"foo" + s: "bar"},
 			new(map[string]string),
 			isExpectedEqMapStringString(map[string]string{"foo" + s: "bar"}),
 		})
 		// is key
-		tests = append(tests, testutil.TranscodeTestCase{
+		tests = append(tests, pgxtest.ValueRoundTripTest{
 			map[string]string{s: "bar"},
 			new(map[string]string),
 			isExpectedEqMapStringString(map[string]string{s: "bar"}),
@@ -161,32 +153,30 @@ func TestHstoreCodec(t *testing.T) {
 		// Special value values
 
 		// at beginning
-		tests = append(tests, testutil.TranscodeTestCase{
+		tests = append(tests, pgxtest.ValueRoundTripTest{
 			map[string]string{"foo": s + "bar"},
 			new(map[string]string),
 			isExpectedEqMapStringString(map[string]string{"foo": s + "bar"}),
 		})
 		// in middle
-		tests = append(tests, testutil.TranscodeTestCase{
+		tests = append(tests, pgxtest.ValueRoundTripTest{
 			map[string]string{"foo": "foo" + s + "bar"},
 			new(map[string]string),
 			isExpectedEqMapStringString(map[string]string{"foo": "foo" + s + "bar"}),
 		})
 		// at end
-		tests = append(tests, testutil.TranscodeTestCase{
+		tests = append(tests, pgxtest.ValueRoundTripTest{
 			map[string]string{"foo": "foo" + s},
 			new(map[string]string),
 			isExpectedEqMapStringString(map[string]string{"foo": "foo" + s}),
 		})
 		// is key
-		tests = append(tests, testutil.TranscodeTestCase{
+		tests = append(tests, pgxtest.ValueRoundTripTest{
 			map[string]string{"foo": s},
 			new(map[string]string),
 			isExpectedEqMapStringString(map[string]string{"foo": s}),
 		})
 	}
 
-	for _, format := range formats {
+	pgxtest.RunValueRoundTripTests(context.Background(), t, ctr, pgxtest.KnownOIDQueryExecModes, "hstore", tests)
-		testutil.RunTranscodeTestsFormat(t, "hstore", tests, conn, format.name, format.code)
-	}
 }

pgtype/inet_test.go

@@ -1,11 +1,12 @@
 package pgtype_test
 
 import (
+	"context"
 	"net"
 	"testing"
 
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func isExpectedEqIPNet(a interface{}) func(interface{}) bool {
@@ -18,7 +19,7 @@ func isExpectedEqIPNet(a interface{}) func(interface{}) bool {
 }
 
 func TestInetTranscode(t *testing.T) {
-	testutil.RunTranscodeTests(t, "inet", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "inet", []pgxtest.ValueRoundTripTest{
 		{mustParseInet(t, "0.0.0.0/32"), new(net.IPNet), isExpectedEqIPNet(mustParseInet(t, "0.0.0.0/32"))},
 		{mustParseInet(t, "127.0.0.1/8"), new(net.IPNet), isExpectedEqIPNet(mustParseInet(t, "127.0.0.1/8"))},
 		{mustParseInet(t, "12.34.56.65/32"), new(net.IPNet), isExpectedEqIPNet(mustParseInet(t, "12.34.56.65/32"))},
@@ -37,7 +38,7 @@ func TestInetTranscode(t *testing.T) {
 func TestCidrTranscode(t *testing.T) {
 	skipCockroachDB(t, "Server does not support cidr type (see https://github.com/cockroachdb/cockroach/issues/18846)")
 
-	testutil.RunTranscodeTests(t, "cidr", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "cidr", []pgxtest.ValueRoundTripTest{
 		{mustParseInet(t, "0.0.0.0/32"), new(net.IPNet), isExpectedEqIPNet(mustParseInet(t, "0.0.0.0/32"))},
 		{mustParseInet(t, "127.0.0.1/32"), new(net.IPNet), isExpectedEqIPNet(mustParseInet(t, "127.0.0.1/32"))},
 		{mustParseInet(t, "12.34.56.0/32"), new(net.IPNet), isExpectedEqIPNet(mustParseInet(t, "12.34.56.0/32"))},

pgtype/int_test.go

@@ -2,15 +2,16 @@
 package pgtype_test
 
 import (
+	"context"
 	"math"
 	"testing"
 
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func TestInt2Codec(t *testing.T) {
-	testutil.RunTranscodeTests(t, "int2", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "int2", []pgxtest.ValueRoundTripTest{
 		{int8(1), new(int16), isExpectedEq(int16(1))},
 		{int16(1), new(int16), isExpectedEq(int16(1))},
 		{int32(1), new(int16), isExpectedEq(int16(1))},
@@ -91,7 +92,7 @@ func TestInt2UnmarshalJSON(t *testing.T) {
 }
 
 func TestInt4Codec(t *testing.T) {
-	testutil.RunTranscodeTests(t, "int4", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "int4", []pgxtest.ValueRoundTripTest{
 		{int8(1), new(int32), isExpectedEq(int32(1))},
 		{int16(1), new(int32), isExpectedEq(int32(1))},
 		{int32(1), new(int32), isExpectedEq(int32(1))},
@@ -172,7 +173,7 @@ func TestInt4UnmarshalJSON(t *testing.T) {
 }
 
 func TestInt8Codec(t *testing.T) {
-	testutil.RunTranscodeTests(t, "int8", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "int8", []pgxtest.ValueRoundTripTest{
 		{int8(1), new(int64), isExpectedEq(int64(1))},
 		{int16(1), new(int64), isExpectedEq(int64(1))},
 		{int32(1), new(int64), isExpectedEq(int64(1))},

pgtype/int_test.go.erb

@@ -10,7 +10,7 @@ import (
 <% [2, 4, 8].each do |pg_byte_size| %>
 <% pg_bit_size = pg_byte_size * 8 %>
 func TestInt<%= pg_byte_size %>Codec(t *testing.T) {
-	testutil.RunTranscodeTests(t, "int<%= pg_byte_size %>", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "int<%= pg_byte_size %>", []pgxtest.ValueRoundTripTest{
 		{int8(1), new(int<%= pg_bit_size %>), isExpectedEq(int<%= pg_bit_size %>(1))},
 		{int16(1), new(int<%= pg_bit_size %>), isExpectedEq(int<%= pg_bit_size %>(1))},
 		{int32(1), new(int<%= pg_bit_size %>), isExpectedEq(int<%= pg_bit_size %>(1))},

pgtype/integration_benchmark_test.go.erb

@@ -18,14 +18,12 @@ import (
 <% rows_columns.each do |rows, columns| %>
 <% [["Text", "pgx.TextFormatCode"], ["Binary", "pgx.BinaryFormatCode"]].each do |format_name, format_code| %>
 func BenchmarkQuery<%= format_name %>FormatDecode_PG_<%= pg_type %>_to_Go_<%= go_type.gsub(/\W/, "_") %>_<%= rows %>_rows_<%= columns %>_columns(b *testing.B) {
-	conn := testutil.MustConnectPgx(b)
+  defaultConnTestRunner.RunTest(context.Background(), b, func(ctx context.Context, _ testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(b, conn)
-
     b.ResetTimer()
     var v [<%= columns %>]<%= go_type %>
     for i := 0; i < b.N; i++ {
       _, err := conn.QueryFunc(
-			context.Background(),
+        ctx,
         `select <% columns.times do |col_idx| %><% if col_idx != 0 %>, <% end %>n::<%= pg_type %> + <%= col_idx%><% end %> from generate_series(1, <%= rows %>) n`,
         []interface{}{pgx.QueryResultFormats{<%= format_code %>}},
         []interface{}{<% columns.times do |col_idx| %><% if col_idx != 0 %>, <% end %>&v[<%= col_idx%>]<% end %>},
@@ -35,6 +33,7 @@ func BenchmarkQuery<%= format_name %>FormatDecode_PG_<%= pg_type %>_to_Go_<%= go
         b.Fatal(err)
       }
     }
+  })
 }
 <% end %>
 <% end %>
@@ -44,14 +43,12 @@ func BenchmarkQuery<%= format_name %>FormatDecode_PG_<%= pg_type %>_to_Go_<%= go
 <% [10, 100, 1000].each do |array_size| %>
 <% [["Text", "pgx.TextFormatCode"], ["Binary", "pgx.BinaryFormatCode"]].each do |format_name, format_code| %>
 func BenchmarkQuery<%= format_name %>FormatDecode_PG_Int4Array_With_Go_Int4Array_<%= array_size %>(b *testing.B) {
-	conn := testutil.MustConnectPgx(b)
+  defaultConnTestRunner.RunTest(context.Background(), b, func(ctx context.Context, _ testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(b, conn)
-
     b.ResetTimer()
     var v []int32
     for i := 0; i < b.N; i++ {
       _, err := conn.QueryFunc(
-			context.Background(),
+        ctx,
         `select array_agg(n) from generate_series(1, <%= array_size %>) n`,
         []interface{}{pgx.QueryResultFormats{<%= format_code %>}},
         []interface{}{&v},
@@ -61,6 +58,7 @@ func BenchmarkQuery<%= format_name %>FormatDecode_PG_Int4Array_With_Go_Int4Array
         b.Fatal(err)
       }
     }
+  })
 }
 <% end %>
 <% end %>

pgtype/interval_test.go

@@ -1,15 +1,16 @@
 package pgtype_test
 
 import (
+	"context"
 	"testing"
 	"time"
 
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func TestIntervalCodec(t *testing.T) {
-	testutil.RunTranscodeTests(t, "interval", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "interval", []pgxtest.ValueRoundTripTest{
 		{
 			pgtype.Interval{Microseconds: 1, Valid: true},
 			new(pgtype.Interval),

pgtype/json_test.go

@@ -1,9 +1,10 @@
 package pgtype_test
 
 import (
+	"context"
 	"testing"
 
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func isExpectedEqMap(a interface{}) func(interface{}) bool {
@@ -39,7 +40,15 @@ func TestJSONCodec(t *testing.T) {
 		Age  int    `json:"age"`
 	}
 
-	testutil.RunTranscodeTests(t, "json", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "json", []pgxtest.ValueRoundTripTest{
+		{nil, new(*jsonStruct), isExpectedEq((*jsonStruct)(nil))},
+		{map[string]interface{}(nil), new(*string), isExpectedEq((*string)(nil))},
+		{map[string]interface{}(nil), new([]byte), isExpectedEqBytes([]byte(nil))},
+		{[]byte(nil), new([]byte), isExpectedEqBytes([]byte(nil))},
+		{nil, new([]byte), isExpectedEqBytes([]byte(nil))},
+	})
+
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, pgxtest.KnownOIDQueryExecModes, "json", []pgxtest.ValueRoundTripTest{
 		{[]byte("{}"), new([]byte), isExpectedEqBytes([]byte("{}"))},
 		{[]byte("null"), new([]byte), isExpectedEqBytes([]byte("null"))},
 		{[]byte("42"), new([]byte), isExpectedEqBytes([]byte("42"))},
@@ -47,10 +56,5 @@ func TestJSONCodec(t *testing.T) {
 		{[]byte(`"hello"`), new(string), isExpectedEq(`"hello"`)},
 		{map[string]interface{}{"foo": "bar"}, new(map[string]interface{}), isExpectedEqMap(map[string]interface{}{"foo": "bar"})},
 		{jsonStruct{Name: "Adam", Age: 10}, new(jsonStruct), isExpectedEq(jsonStruct{Name: "Adam", Age: 10})},
-		{nil, new(*jsonStruct), isExpectedEq((*jsonStruct)(nil))},
-		{map[string]interface{}(nil), new(*string), isExpectedEq((*string)(nil))},
-		{map[string]interface{}(nil), new([]byte), isExpectedEqBytes([]byte(nil))},
-		{[]byte(nil), new([]byte), isExpectedEqBytes([]byte(nil))},
-		{nil, new([]byte), isExpectedEqBytes([]byte(nil))},
 	})
 }

pgtype/jsonb_test.go

@@ -1,9 +1,10 @@
 package pgtype_test
 
 import (
+	"context"
 	"testing"
 
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func TestJSONBTranscode(t *testing.T) {
@@ -12,7 +13,15 @@ func TestJSONBTranscode(t *testing.T) {
 		Age  int    `json:"age"`
 	}
 
-	testutil.RunTranscodeTests(t, "jsonb", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "jsonb", []pgxtest.ValueRoundTripTest{
+		{nil, new(*jsonStruct), isExpectedEq((*jsonStruct)(nil))},
+		{map[string]interface{}(nil), new(*string), isExpectedEq((*string)(nil))},
+		{map[string]interface{}(nil), new([]byte), isExpectedEqBytes([]byte(nil))},
+		{[]byte(nil), new([]byte), isExpectedEqBytes([]byte(nil))},
+		{nil, new([]byte), isExpectedEqBytes([]byte(nil))},
+	})
+
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, pgxtest.KnownOIDQueryExecModes, "jsonb", []pgxtest.ValueRoundTripTest{
 		{[]byte("{}"), new([]byte), isExpectedEqBytes([]byte("{}"))},
 		{[]byte("null"), new([]byte), isExpectedEqBytes([]byte("null"))},
 		{[]byte("42"), new([]byte), isExpectedEqBytes([]byte("42"))},
@@ -20,10 +29,5 @@ func TestJSONBTranscode(t *testing.T) {
 		{[]byte(`"hello"`), new(string), isExpectedEq(`"hello"`)},
 		{map[string]interface{}{"foo": "bar"}, new(map[string]interface{}), isExpectedEqMap(map[string]interface{}{"foo": "bar"})},
 		{jsonStruct{Name: "Adam", Age: 10}, new(jsonStruct), isExpectedEq(jsonStruct{Name: "Adam", Age: 10})},
-		{nil, new(*jsonStruct), isExpectedEq((*jsonStruct)(nil))},
-		{map[string]interface{}(nil), new(*string), isExpectedEq((*string)(nil))},
-		{map[string]interface{}(nil), new([]byte), isExpectedEqBytes([]byte(nil))},
-		{[]byte(nil), new([]byte), isExpectedEqBytes([]byte(nil))},
-		{nil, new([]byte), isExpectedEqBytes([]byte(nil))},
 	})
 }

pgtype/line_test.go

@@ -4,15 +4,16 @@ import (
 	"context"
 	"testing"
 
+	pgx "github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func TestLineTranscode(t *testing.T) {
-	skipCockroachDB(t, "Server does not support type line")
+	ctr := defaultConnTestRunner
+	ctr.AfterConnect = func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
+		pgxtest.SkipCockroachDB(t, conn, "Server does not support type line")
 
-	conn := testutil.MustConnectPgx(t)
-	defer conn.Close(context.Background())
 		if _, ok := conn.TypeMap().TypeForName("line"); !ok {
 			t.Skip("Skipping due to no line type")
 		}
@@ -26,8 +27,9 @@ func TestLineTranscode(t *testing.T) {
 		if isPG93 {
 			t.Skip("Skipping due to unimplemented line type in PG 9.3")
 		}
+	}
 
-	testutil.RunTranscodeTests(t, "line", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, ctr, nil, "line", []pgxtest.ValueRoundTripTest{
 		{
 			pgtype.Line{
 				A: 1.23, B: 4.56, C: 7.89012345,

pgtype/lseg_test.go

@@ -1,16 +1,17 @@
 package pgtype_test
 
 import (
+	"context"
 	"testing"
 
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func TestLsegTranscode(t *testing.T) {
 	skipCockroachDB(t, "Server does not support type lseg")
 
-	testutil.RunTranscodeTests(t, "lseg", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "lseg", []pgxtest.ValueRoundTripTest{
 		{
 			pgtype.Lseg{
 				P:     [2]pgtype.Vec2{{3.14, 1.678}, {7.1, 5.2345678901}},

pgtype/macaddr_test.go

@@ -2,10 +2,11 @@ package pgtype_test
 
 import (
 	"bytes"
+	"context"
 	"net"
 	"testing"
 
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func isExpectedEqHardwareAddr(a interface{}) func(interface{}) bool {
@@ -28,7 +29,8 @@ func isExpectedEqHardwareAddr(a interface{}) func(interface{}) bool {
 func TestMacaddrCodec(t *testing.T) {
 	skipCockroachDB(t, "Server does not support type macaddr")
 
-	testutil.RunTranscodeTests(t, "macaddr", []testutil.TranscodeTestCase{
+	// Only testing known OID query exec modes as net.HardwareAddr could map to macaddr or macaddr8.
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, pgxtest.KnownOIDQueryExecModes, "macaddr", []pgxtest.ValueRoundTripTest{
 		{
 			mustParseMacaddr(t, "01:23:45:67:89:ab"),
 			new(net.HardwareAddr),

pgtype/numeric_test.go

@@ -9,8 +9,9 @@ import (
 	"strconv"
 	"testing"
 
+	pgx "github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -77,7 +78,7 @@ func TestNumericCodec(t *testing.T) {
 	max.Add(max, big.NewInt(1))
 	longestNumeric := pgtype.Numeric{Int: max, Exp: -16383, Valid: true}
 
-	testutil.RunTranscodeTests(t, "numeric", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "numeric", []pgxtest.ValueRoundTripTest{
 		{mustParseNumeric(t, "1"), new(pgtype.Numeric), isExpectedEqNumeric(mustParseNumeric(t, "1"))},
 		{mustParseNumeric(t, "3.14159"), new(pgtype.Numeric), isExpectedEqNumeric(mustParseNumeric(t, "3.14159"))},
 		{mustParseNumeric(t, "100010001"), new(pgtype.Numeric), isExpectedEqNumeric(mustParseNumeric(t, "100010001"))},
@@ -118,7 +119,7 @@ func TestNumericCodecInfinity(t *testing.T) {
 	skipCockroachDB(t, "server formats numeric text format differently")
 	skipPostgreSQLVersionLessThan(t, 14)
 
-	testutil.RunTranscodeTests(t, "numeric", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "numeric", []pgxtest.ValueRoundTripTest{
 		{math.Inf(1), new(float64), isExpectedEq(math.Inf(1))},
 		{float32(math.Inf(1)), new(float32), isExpectedEq(float32(math.Inf(1)))},
 		{math.Inf(-1), new(float64), isExpectedEq(math.Inf(-1))},
@@ -159,29 +160,28 @@ func TestNumericCodecFuzz(t *testing.T) {
 	max := &big.Int{}
 	max.SetString("9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999", 10)
 
-	tests := make([]testutil.TranscodeTestCase, 0, 2000)
+	tests := make([]pgxtest.ValueRoundTripTest, 0, 2000)
 	for i := 0; i < 10; i++ {
 		for j := -50; j < 50; j++ {
 			num := (&big.Int{}).Rand(r, max)
 
 			n := pgtype.Numeric{Int: num, Exp: int32(j), Valid: true}
-			tests = append(tests, testutil.TranscodeTestCase{n, new(pgtype.Numeric), isExpectedEqNumeric(n)})
+			tests = append(tests, pgxtest.ValueRoundTripTest{n, new(pgtype.Numeric), isExpectedEqNumeric(n)})
 
 			negNum := &big.Int{}
 			negNum.Neg(num)
 			n = pgtype.Numeric{Int: negNum, Exp: int32(j), Valid: true}
-			tests = append(tests, testutil.TranscodeTestCase{n, new(pgtype.Numeric), isExpectedEqNumeric(n)})
+			tests = append(tests, pgxtest.ValueRoundTripTest{n, new(pgtype.Numeric), isExpectedEqNumeric(n)})
 		}
 	}
 
-	testutil.RunTranscodeTests(t, "numeric", tests)
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "numeric", tests)
 }
 
 func TestNumericMarshalJSON(t *testing.T) {
 	skipCockroachDB(t, "server formats numeric text format differently")
 
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
 
 		for i, tt := range []struct {
 			decString string
@@ -201,7 +201,7 @@ func TestNumericMarshalJSON(t *testing.T) {
 		} {
 			var num pgtype.Numeric
 			var pgJSON string
-		err := conn.QueryRow(context.Background(), `select $1::numeric, to_json($1::numeric)`, tt.decString).Scan(&num, &pgJSON)
+			err := conn.QueryRow(ctx, `select $1::numeric, to_json($1::numeric)`, tt.decString).Scan(&num, &pgJSON)
 			require.NoErrorf(t, err, "%d", i)
 
 			goJSON, err := json.Marshal(num)
@@ -209,4 +209,5 @@ func TestNumericMarshalJSON(t *testing.T) {
 
 			require.Equal(t, pgJSON, string(goJSON))
 		}
+	})
 }

pgtype/path_test.go

@@ -1,10 +1,11 @@
 package pgtype_test
 
 import (
+	"context"
 	"testing"
 
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func isExpectedEqPath(a interface{}) func(interface{}) bool {
@@ -29,7 +30,7 @@ func isExpectedEqPath(a interface{}) func(interface{}) bool {
 func TestPathTranscode(t *testing.T) {
 	skipCockroachDB(t, "Server does not support type path")
 
-	testutil.RunTranscodeTests(t, "path", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "path", []pgxtest.ValueRoundTripTest{
 		{
 			pgtype.Path{
 				P:      []pgtype.Vec2{{3.14, 1.678901234}, {7.1, 5.234}},

pgtype/pgtype.go

@@ -374,7 +374,7 @@ func NewMap() *Map {
 	registerDefaultPgTypeVariants("daterange", "_daterange", Daterange{})
 	registerDefaultPgTypeVariants("float4", "_float4", Float4{})
 	registerDefaultPgTypeVariants("float8", "_float8", Float8{})
-	registerDefaultPgTypeVariants("float8range", "_float8range", Float8range{})
+	registerDefaultPgTypeVariants("numrange", "_numrange", Float8range{}) // There is no PostgreSQL builtin float8range so map it to numrange.
 	registerDefaultPgTypeVariants("inet", "_inet", Inet{})
 	registerDefaultPgTypeVariants("int2", "_int2", Int2{})
 	registerDefaultPgTypeVariants("int4", "_int4", Int4{})

pgtype/pgtype_test.go

@@ -1,21 +1,34 @@
 package pgtype_test
 
 import (
+	"context"
 	"database/sql"
 	"errors"
 	"net"
+	"os"
 	"regexp"
 	"strconv"
 	"testing"
 
 	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 	_ "github.com/jackc/pgx/v5/stdlib"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
+var defaultConnTestRunner pgxtest.ConnTestRunner
+
+func init() {
+	defaultConnTestRunner = pgxtest.DefaultConnTestRunner()
+	defaultConnTestRunner.CreateConfig = func(ctx context.Context, t testing.TB) *pgx.ConnConfig {
+		config, err := pgx.ParseConfig(os.Getenv("PGX_TEST_DATABASE"))
+		require.NoError(t, err)
+		return config
+	}
+}
+
 // Test for renamed types
 type _string string
 type _bool bool
@@ -70,8 +83,11 @@ func mustParseMacaddr(t testing.TB, s string) net.HardwareAddr {
 }
 
 func skipCockroachDB(t testing.TB, msg string) {
-	conn := testutil.MustConnectPgx(t)
+	conn, err := pgx.Connect(context.Background(), os.Getenv("PGX_TEST_DATABASE"))
-	defer testutil.MustCloseContext(t, conn)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer conn.Close(context.Background())
 
 	if conn.PgConn().ParameterStatus("crdb_version") != "" {
 		t.Skip(msg)
@@ -79,8 +95,11 @@ func skipCockroachDB(t testing.TB, msg string) {
 }
 
 func skipPostgreSQLVersionLessThan(t testing.TB, minVersion int64) {
-	conn := testutil.MustConnectPgx(t)
+	conn, err := pgx.Connect(context.Background(), os.Getenv("PGX_TEST_DATABASE"))
-	defer testutil.MustCloseContext(t, conn)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer conn.Close(context.Background())
 
 	serverVersionStr := conn.PgConn().ParameterStatus("server_version")
 	serverVersionStr = regexp.MustCompile(`^[0-9]+`).FindString(serverVersionStr)

pgtype/point_test.go

@@ -1,18 +1,19 @@
 package pgtype_test
 
 import (
+	"context"
 	"reflect"
 	"testing"
 
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 	"github.com/stretchr/testify/require"
 )
 
 func TestPointCodec(t *testing.T) {
 	skipCockroachDB(t, "Server does not support type point")
 
-	testutil.RunTranscodeTests(t, "point", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "point", []pgxtest.ValueRoundTripTest{
 		{
 			pgtype.Point{P: pgtype.Vec2{1.234, 5.6789012345}, Valid: true},
 			new(pgtype.Point),

pgtype/polygon_test.go

@@ -1,10 +1,11 @@
 package pgtype_test
 
 import (
+	"context"
 	"testing"
 
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func isExpectedEqPolygon(a interface{}) func(interface{}) bool {
@@ -29,7 +30,7 @@ func isExpectedEqPolygon(a interface{}) func(interface{}) bool {
 func TestPolygonTranscode(t *testing.T) {
 	skipCockroachDB(t, "Server does not support type polygon")
 
-	testutil.RunTranscodeTests(t, "polygon", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "polygon", []pgxtest.ValueRoundTripTest{
 		{
 			pgtype.Polygon{
 				P:     []pgtype.Vec2{{3.14, 1.678901234}, {7.1, 5.234}, {5.0, 3.234}},

pgtype/qchar_test.go

@@ -1,22 +1,24 @@
 package pgtype_test
 
 import (
+	"context"
 	"math"
 	"testing"
 
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func TestQcharTranscode(t *testing.T) {
 	skipCockroachDB(t, "Server does not support qchar")
 
-	var tests []testutil.TranscodeTestCase
+	var tests []pgxtest.ValueRoundTripTest
 	for i := 0; i <= math.MaxUint8; i++ {
-		tests = append(tests, testutil.TranscodeTestCase{rune(i), new(rune), isExpectedEq(rune(i))})
+		tests = append(tests, pgxtest.ValueRoundTripTest{rune(i), new(rune), isExpectedEq(rune(i))})
-		tests = append(tests, testutil.TranscodeTestCase{byte(i), new(byte), isExpectedEq(byte(i))})
+		tests = append(tests, pgxtest.ValueRoundTripTest{byte(i), new(byte), isExpectedEq(byte(i))})
 	}
-	tests = append(tests, testutil.TranscodeTestCase{nil, new(*rune), isExpectedEq((*rune)(nil))})
+	tests = append(tests, pgxtest.ValueRoundTripTest{nil, new(*rune), isExpectedEq((*rune)(nil))})
-	tests = append(tests, testutil.TranscodeTestCase{nil, new(*byte), isExpectedEq((*byte)(nil))})
+	tests = append(tests, pgxtest.ValueRoundTripTest{nil, new(*byte), isExpectedEq((*byte)(nil))})
 
-	testutil.RunTranscodeTests(t, `"char"`, tests)
+	// Can only test with known OIDs as rune and byte would be considered numbers.
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, pgxtest.KnownOIDQueryExecModes, `"char"`, tests)
 }

pgtype/range_codec_test.go

@@ -4,15 +4,16 @@ import (
 	"context"
 	"testing"
 
+	pgx "github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 	"github.com/stretchr/testify/require"
 )
 
 func TestRangeCodecTranscode(t *testing.T) {
 	skipCockroachDB(t, "Server does not support range types (see https://github.com/cockroachdb/cockroach/issues/27791)")
 
-	testutil.RunTranscodeTests(t, "int4range", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "int4range", []pgxtest.ValueRoundTripTest{
 		{
 			pgtype.Int4range{LowerType: pgtype.Empty, UpperType: pgtype.Empty, Valid: true},
 			new(pgtype.Int4range),
@@ -39,9 +40,12 @@ func TestRangeCodecTranscode(t *testing.T) {
 }
 
 func TestRangeCodecTranscodeCompatibleRangeElementTypes(t *testing.T) {
-	skipCockroachDB(t, "Server does not support range types (see https://github.com/cockroachdb/cockroach/issues/27791)")
+	ctr := defaultConnTestRunner
+	ctr.AfterConnect = func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
+		pgxtest.SkipCockroachDB(t, conn, "Server does not support range types (see https://github.com/cockroachdb/cockroach/issues/27791)")
+	}
 
-	testutil.RunTranscodeTests(t, "numrange", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, ctr, nil, "numrange", []pgxtest.ValueRoundTripTest{
 		{
 			pgtype.Float8range{LowerType: pgtype.Empty, UpperType: pgtype.Empty, Valid: true},
 			new(pgtype.Float8range),
@@ -70,8 +74,7 @@ func TestRangeCodecTranscodeCompatibleRangeElementTypes(t *testing.T) {
 func TestRangeCodecScanRangeTwiceWithUnbounded(t *testing.T) {
 	skipCockroachDB(t, "Server does not support range types (see https://github.com/cockroachdb/cockroach/issues/27791)")
 
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
 
 		var r pgtype.Int4range
 
@@ -90,7 +93,7 @@ func TestRangeCodecScanRangeTwiceWithUnbounded(t *testing.T) {
 			r,
 		)
 
-	err = conn.QueryRow(context.Background(), `select '[1,)'::int4range`).Scan(&r)
+		err = conn.QueryRow(ctx, `select '[1,)'::int4range`).Scan(&r)
 		require.NoError(t, err)
 
 		require.Equal(
@@ -105,7 +108,7 @@ func TestRangeCodecScanRangeTwiceWithUnbounded(t *testing.T) {
 			r,
 		)
 
-	err = conn.QueryRow(context.Background(), `select 'empty'::int4range`).Scan(&r)
+		err = conn.QueryRow(ctx, `select 'empty'::int4range`).Scan(&r)
 		require.NoError(t, err)
 
 		require.Equal(
@@ -119,13 +122,13 @@ func TestRangeCodecScanRangeTwiceWithUnbounded(t *testing.T) {
 			},
 			r,
 		)
+	})
 }
 
 func TestRangeCodecDecodeValue(t *testing.T) {
 	skipCockroachDB(t, "Server does not support range types (see https://github.com/cockroachdb/cockroach/issues/27791)")
 
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, _ testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
 
 		for _, tt := range []struct {
 			sql      string
@@ -143,7 +146,7 @@ func TestRangeCodecDecodeValue(t *testing.T) {
 			},
 		} {
 			t.Run(tt.sql, func(t *testing.T) {
-			rows, err := conn.Query(context.Background(), tt.sql)
+				rows, err := conn.Query(ctx, tt.sql)
 				require.NoError(t, err)
 
 				for rows.Next() {
@@ -156,4 +159,5 @@ func TestRangeCodecDecodeValue(t *testing.T) {
 				require.NoError(t, rows.Err())
 			})
 		}
+	})
 }

pgtype/record_codec_test.go

@@ -4,30 +4,27 @@ import (
 	"context"
 	"testing"
 
+	pgx "github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
 	"github.com/stretchr/testify/require"
 )
 
 func TestRecordCodec(t *testing.T) {
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
-
 		var a string
 		var b int32
-	err := conn.QueryRow(context.Background(), `select row('foo'::text, 42::int4)`).Scan(pgtype.CompositeFields{&a, &b})
+		err := conn.QueryRow(ctx, `select row('foo'::text, 42::int4)`).Scan(pgtype.CompositeFields{&a, &b})
 		require.NoError(t, err)
 
 		require.Equal(t, "foo", a)
 		require.Equal(t, int32(42), b)
+	})
 }
 
 func TestRecordCodecDecodeValue(t *testing.T) {
 	skipCockroachDB(t, "Server converts row int4 to int8")
 
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, _ testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
-
 		for _, tt := range []struct {
 			sql      string
 			expected interface{}
@@ -72,4 +69,5 @@ func TestRecordCodecDecodeValue(t *testing.T) {
 				require.NoError(t, rows.Err())
 			})
 		}
+	})
 }

pgtype/testutil/testutil.go

@@ -1,85 +0,0 @@
-package testutil
-
-import (
-	"context"
-	"fmt"
-	"os"
-	"reflect"
-	"testing"
-
-	"github.com/jackc/pgx/v5"
-	_ "github.com/jackc/pgx/v5/stdlib"
-)
-
-func MustConnectPgx(t testing.TB) *pgx.Conn {
-	conn, err := pgx.Connect(context.Background(), os.Getenv("PGX_TEST_DATABASE"))
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	return conn
-}
-
-func MustClose(t testing.TB, conn interface {
-	Close() error
-}) {
-	err := conn.Close()
-	if err != nil {
-		t.Fatal(err)
-	}
-}
-
-func MustCloseContext(t testing.TB, conn interface {
-	Close(context.Context) error
-}) {
-	err := conn.Close(context.Background())
-	if err != nil {
-		t.Fatal(err)
-	}
-}
-
-type TranscodeTestCase struct {
-	Src  interface{}
-	Dst  interface{}
-	Test func(interface{}) bool
-}
-
-func RunTranscodeTests(t testing.TB, pgTypeName string, tests []TranscodeTestCase) {
-	conn := MustConnectPgx(t)
-	defer MustCloseContext(t, conn)
-
-	formats := []struct {
-		name string
-		code int16
-	}{
-		{name: "TextFormat", code: pgx.TextFormatCode},
-		{name: "BinaryFormat", code: pgx.BinaryFormatCode},
-	}
-
-	for _, format := range formats {
-		RunTranscodeTestsFormat(t, pgTypeName, tests, conn, format.name, format.code)
-	}
-}
-
-func RunTranscodeTestsFormat(t testing.TB, pgTypeName string, tests []TranscodeTestCase, conn *pgx.Conn, formatName string, formatCode int16) {
-	_, err := conn.Prepare(context.Background(), "test", fmt.Sprintf("select $1::%s", pgTypeName))
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	for i, tt := range tests {
-		err := conn.QueryRow(context.Background(), "test", pgx.QueryResultFormats{formatCode}, tt.Src).Scan(tt.Dst)
-		if err != nil {
-			t.Errorf("%s %d: %v", formatName, i, err)
-		}
-
-		dst := reflect.ValueOf(tt.Dst)
-		if dst.Kind() == reflect.Ptr {
-			dst = dst.Elem()
-		}
-
-		if !tt.Test(dst.Interface()) {
-			t.Errorf("%s %d: unexpected result for %v: %v", formatName, i, tt.Src, dst.Interface())
-		}
-	}
-}

pgtype/text_test.go

@@ -4,8 +4,9 @@ import (
 	"context"
 	"testing"
 
+	pgx "github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 	"github.com/stretchr/testify/require"
 )
 
@@ -17,7 +18,7 @@ func (someFmtStringer) String() string {
 
 func TestTextCodec(t *testing.T) {
 	for _, pgTypeName := range []string{"text", "varchar"} {
-		testutil.RunTranscodeTests(t, pgTypeName, []testutil.TranscodeTestCase{
+		pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, pgTypeName, []pgxtest.ValueRoundTripTest{
 			{
 				pgtype.Text{String: "", Valid: true},
 				new(pgtype.Text),
@@ -31,6 +32,10 @@ func TestTextCodec(t *testing.T) {
 			{nil, new(pgtype.Text), isExpectedEq(pgtype.Text{})},
 			{"foo", new(string), isExpectedEq("foo")},
 			{someFmtStringer{}, new(string), isExpectedEq("some fmt.Stringer")},
+		})
+
+		// rune requires known OID because otherwise it is considered an int32.
+		pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, pgxtest.KnownOIDQueryExecModes, pgTypeName, []pgxtest.ValueRoundTripTest{
 			{rune('R'), new(rune), isExpectedEq(rune('R'))},
 		})
 	}
@@ -47,7 +52,7 @@ func TestTextCodec(t *testing.T) {
 //
 // So this is simply a smoke test of the name type.
 func TestTextCodecName(t *testing.T) {
-	testutil.RunTranscodeTests(t, "name", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "name", []pgxtest.ValueRoundTripTest{
 		{
 			pgtype.Text{String: "", Valid: true},
 			new(pgtype.Text),
@@ -67,7 +72,7 @@ func TestTextCodecName(t *testing.T) {
 func TestTextCodecBPChar(t *testing.T) {
 	skipCockroachDB(t, "Server does not properly handle bpchar with multi-byte character")
 
-	testutil.RunTranscodeTests(t, "char(3)", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "char(3)", []pgxtest.ValueRoundTripTest{
 		{
 			pgtype.Text{String: "a  ", Valid: true},
 			new(pgtype.Text),
@@ -94,12 +99,12 @@ func TestTextCodecBPChar(t *testing.T) {
 //
 // It only supports the text format.
 func TestTextCodecACLItem(t *testing.T) {
-	skipCockroachDB(t, "Server does not support type aclitem")
+	ctr := defaultConnTestRunner
+	ctr.AfterConnect = func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
+		pgxtest.SkipCockroachDB(t, conn, "Server does not support type aclitem")
+	}
 
-	conn := testutil.MustConnectPgx(t)
+	pgxtest.RunValueRoundTripTests(context.Background(), t, ctr, nil, "aclitem", []pgxtest.ValueRoundTripTest{
-	defer testutil.MustCloseContext(t, conn)
-
-	testutil.RunTranscodeTestsFormat(t, "aclitem", []testutil.TranscodeTestCase{
 		{
 			pgtype.Text{String: "postgres=arwdDxt/postgres", Valid: true},
 			new(pgtype.Text),
@@ -107,14 +112,13 @@ func TestTextCodecACLItem(t *testing.T) {
 		},
 		{pgtype.Text{}, new(pgtype.Text), isExpectedEq(pgtype.Text{})},
 		{nil, new(pgtype.Text), isExpectedEq(pgtype.Text{})},
-	}, conn, "Text", pgtype.TextFormatCode)
+	})
 }
 
 func TestTextCodecACLItemRoleWithSpecialCharacters(t *testing.T) {
-	conn := testutil.MustConnectPgx(t)
+	ctr := defaultConnTestRunner
-	defer testutil.MustCloseContext(t, conn)
+	ctr.AfterConnect = func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-
+		pgxtest.SkipCockroachDB(t, conn, "Server does not support type aclitem")
-	ctx := context.Background()
 
 		// The tricky test user, below, has to actually exist so that it can be used in a test
 		// of aclitem formatting. It turns out aclitems cannot contain non-existing users/roles.
@@ -126,14 +130,15 @@ func TestTextCodecACLItemRoleWithSpecialCharacters(t *testing.T) {
 		if commandTag.RowsAffected() == 0 {
 			t.Skipf("Role with special characters does not exist.")
 		}
+	}
 
-	testutil.RunTranscodeTestsFormat(t, "aclitem", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, ctr, nil, "aclitem", []pgxtest.ValueRoundTripTest{
 		{
 			pgtype.Text{String: `postgres=arwdDxt/" tricky, ' } "" \ test user "`, Valid: true},
 			new(pgtype.Text),
 			isExpectedEq(pgtype.Text{String: `postgres=arwdDxt/" tricky, ' } "" \ test user "`, Valid: true}),
 		},
-	}, conn, "Text", pgtype.TextFormatCode)
+	})
 }
 
 func TestTextMarshalJSON(t *testing.T) {

pgtype/tid_test.go

@@ -1,16 +1,17 @@
 package pgtype_test
 
 import (
+	"context"
 	"testing"
 
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func TestTIDCodec(t *testing.T) {
 	skipCockroachDB(t, "Server does not support type tid")
 
-	testutil.RunTranscodeTests(t, "tid", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "tid", []pgxtest.ValueRoundTripTest{
 		{
 			pgtype.TID{BlockNumber: 42, OffsetNumber: 43, Valid: true},
 			new(pgtype.TID),

pgtype/time_test.go

@@ -1,15 +1,16 @@
 package pgtype_test
 
 import (
+	"context"
 	"testing"
 	"time"
 
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func TestTimeCodec(t *testing.T) {
-	testutil.RunTranscodeTests(t, "time", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "time", []pgxtest.ValueRoundTripTest{
 		{
 			pgtype.Time{Microseconds: 0, Valid: true},
 			new(pgtype.Time),

pgtype/timestamp.go

@@ -4,6 +4,7 @@ import (
 	"database/sql/driver"
 	"encoding/binary"
 	"fmt"
+	"strings"
 	"time"
 
 	"github.com/jackc/pgx/v5/internal/pgio"
@@ -127,12 +128,29 @@ func (encodePlanTimestampCodecText) Encode(value interface{}, buf []byte) (newBu
 		return nil, err
 	}
 
+	if !ts.Valid {
+		return nil, nil
+	}
+
 	var s string
 
 	switch ts.InfinityModifier {
 	case Finite:
 		t := discardTimeZone(ts.Time)
+
+		// Year 0000 is 1 BC
+		bc := false
+		if year := t.Year(); year <= 0 {
+			year = -year + 1
+			t = time.Date(year, t.Month(), t.Day(), t.Hour(), t.Minute(), t.Second(), t.Nanosecond(), time.UTC)
+			bc = true
+		}
+
 		s = t.Truncate(time.Microsecond).Format(pgTimestampFormat)
+
+		if bc {
+			s = s + " BC"
+		}
 	case Infinity:
 		s = "infinity"
 	case NegativeInfinity:
@@ -219,11 +237,21 @@ func (scanPlanTextTimestampToTimestampScanner) Scan(src []byte, dst interface{})
 	case "-infinity":
 		ts = Timestamp{Valid: true, InfinityModifier: -Infinity}
 	default:
+		bc := false
+		if strings.HasSuffix(sbuf, " BC") {
+			sbuf = sbuf[:len(sbuf)-3]
+			bc = true
+		}
 		tim, err := time.Parse(pgTimestampFormat, sbuf)
 		if err != nil {
 			return err
 		}
 
+		if bc {
+			year := -tim.Year() + 1
+			tim = time.Date(year, tim.Month(), tim.Day(), tim.Hour(), tim.Minute(), tim.Second(), tim.Nanosecond(), tim.Location())
+		}
+
 		ts = Timestamp{Time: tim, Valid: true}
 	}
 

pgtype/timestamp_test.go

@@ -5,15 +5,21 @@ import (
 	"testing"
 	"time"
 
+	pgx "github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 	"github.com/stretchr/testify/require"
 )
 
 func TestTimestampCodec(t *testing.T) {
 	skipCockroachDB(t, "Server does not support infinite timestamps (see https://github.com/cockroachdb/cockroach/issues/41564)")
 
-	testutil.RunTranscodeTests(t, "timestamp", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "timestamp", []pgxtest.ValueRoundTripTest{
+		{time.Date(-100, 1, 1, 0, 0, 0, 0, time.UTC), new(time.Time), isExpectedEqTime(time.Date(-100, 1, 1, 0, 0, 0, 0, time.UTC))},
+		{time.Date(-1, 1, 1, 0, 0, 0, 0, time.UTC), new(time.Time), isExpectedEqTime(time.Date(-1, 1, 1, 0, 0, 0, 0, time.UTC))},
+		{time.Date(0, 1, 1, 0, 0, 0, 0, time.UTC), new(time.Time), isExpectedEqTime(time.Date(0, 1, 1, 0, 0, 0, 0, time.UTC))},
+		{time.Date(1, 1, 1, 0, 0, 0, 0, time.UTC), new(time.Time), isExpectedEqTime(time.Date(1, 1, 1, 0, 0, 0, 0, time.UTC))},
+
 		{time.Date(1900, 1, 1, 0, 0, 0, 0, time.UTC), new(time.Time), isExpectedEqTime(time.Date(1900, 1, 1, 0, 0, 0, 0, time.UTC))},
 		{time.Date(1970, 1, 1, 0, 0, 0, 0, time.UTC), new(time.Time), isExpectedEqTime(time.Date(1970, 1, 1, 0, 0, 0, 0, time.UTC))},
 		{time.Date(1999, 12, 31, 0, 0, 0, 0, time.UTC), new(time.Time), isExpectedEqTime(time.Date(1999, 12, 31, 0, 0, 0, 0, time.UTC))},
@@ -34,19 +40,18 @@ func TestTimestampCodec(t *testing.T) {
 
 // https://github.com/jackc/pgx/v4/pgtype/pull/128
 func TestTimestampTranscodeBigTimeBinary(t *testing.T) {
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
-
 		in := &pgtype.Timestamp{Time: time.Date(294276, 12, 31, 23, 59, 59, 999999000, time.UTC), Valid: true}
 		var out pgtype.Timestamp
 
-	err := conn.QueryRow(context.Background(), "select $1::timestamp", in).Scan(&out)
+		err := conn.QueryRow(ctx, "select $1::timestamp", in).Scan(&out)
 		if err != nil {
 			t.Fatal(err)
 		}
 
 		require.Equal(t, in.Valid, out.Valid)
 		require.Truef(t, in.Time.Equal(out.Time), "expected %v got %v", in.Time, out.Time)
+	})
 }
 
 // https://github.com/jackc/pgtype/issues/74

pgtype/timestamptz.go

@@ -5,6 +5,7 @@ import (
 	"encoding/binary"
 	"encoding/json"
 	"fmt"
+	"strings"
 	"time"
 
 	"github.com/jackc/pgx/v5/internal/pgio"
@@ -184,11 +185,30 @@ func (encodePlanTimestamptzCodecText) Encode(value interface{}, buf []byte) (new
 		return nil, err
 	}
 
+	if !ts.Valid {
+		return nil, nil
+	}
+
 	var s string
 
 	switch ts.InfinityModifier {
 	case Finite:
-		s = ts.Time.UTC().Truncate(time.Microsecond).Format(pgTimestamptzSecondFormat)
+
+		t := ts.Time.UTC().Truncate(time.Microsecond)
+
+		// Year 0000 is 1 BC
+		bc := false
+		if year := t.Year(); year <= 0 {
+			year = -year + 1
+			t = time.Date(year, t.Month(), t.Day(), t.Hour(), t.Minute(), t.Second(), t.Nanosecond(), time.UTC)
+			bc = true
+		}
+
+		s = t.Format(pgTimestamptzSecondFormat)
+
+		if bc {
+			s = s + " BC"
+		}
 	case Infinity:
 		s = "infinity"
 	case NegativeInfinity:
@@ -267,6 +287,12 @@ func (scanPlanTextTimestamptzToTimestamptzScanner) Scan(src []byte, dst interfac
 	case "-infinity":
 		tstz = Timestamptz{Valid: true, InfinityModifier: -Infinity}
 	default:
+		bc := false
+		if strings.HasSuffix(sbuf, " BC") {
+			sbuf = sbuf[:len(sbuf)-3]
+			bc = true
+		}
+
 		var format string
 		if len(sbuf) >= 9 && (sbuf[len(sbuf)-9] == '-' || sbuf[len(sbuf)-9] == '+') {
 			format = pgTimestamptzSecondFormat
@@ -281,6 +307,11 @@ func (scanPlanTextTimestamptzToTimestamptzScanner) Scan(src []byte, dst interfac
 			return err
 		}
 
+		if bc {
+			year := -tim.Year() + 1
+			tim = time.Date(year, tim.Month(), tim.Day(), tim.Hour(), tim.Minute(), tim.Second(), tim.Nanosecond(), tim.Location())
+		}
+
 		tstz = Timestamptz{Time: tim, Valid: true}
 	}
 

pgtype/timestamptz_test.go

@@ -5,15 +5,21 @@ import (
 	"testing"
 	"time"
 
+	pgx "github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 	"github.com/stretchr/testify/require"
 )
 
 func TestTimestamptzCodec(t *testing.T) {
 	skipCockroachDB(t, "Server does not support infinite timestamps (see https://github.com/cockroachdb/cockroach/issues/41564)")
 
-	testutil.RunTranscodeTests(t, "timestamptz", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "timestamptz", []pgxtest.ValueRoundTripTest{
+		{time.Date(-100, 1, 1, 0, 0, 0, 0, time.Local), new(time.Time), isExpectedEqTime(time.Date(-100, 1, 1, 0, 0, 0, 0, time.Local))},
+		{time.Date(-1, 1, 1, 0, 0, 0, 0, time.Local), new(time.Time), isExpectedEqTime(time.Date(-1, 1, 1, 0, 0, 0, 0, time.Local))},
+		{time.Date(0, 1, 1, 0, 0, 0, 0, time.Local), new(time.Time), isExpectedEqTime(time.Date(0, 1, 1, 0, 0, 0, 0, time.Local))},
+		{time.Date(1, 1, 1, 0, 0, 0, 0, time.Local), new(time.Time), isExpectedEqTime(time.Date(1, 1, 1, 0, 0, 0, 0, time.Local))},
+
 		{time.Date(1900, 1, 1, 0, 0, 0, 0, time.Local), new(time.Time), isExpectedEqTime(time.Date(1900, 1, 1, 0, 0, 0, 0, time.Local))},
 		{time.Date(1970, 1, 1, 0, 0, 0, 0, time.Local), new(time.Time), isExpectedEqTime(time.Date(1970, 1, 1, 0, 0, 0, 0, time.Local))},
 		{time.Date(1999, 12, 31, 0, 0, 0, 0, time.Local), new(time.Time), isExpectedEqTime(time.Date(1999, 12, 31, 0, 0, 0, 0, time.Local))},
@@ -34,19 +40,18 @@ func TestTimestamptzCodec(t *testing.T) {
 
 // https://github.com/jackc/pgx/v4/pgtype/pull/128
 func TestTimestamptzTranscodeBigTimeBinary(t *testing.T) {
-	conn := testutil.MustConnectPgx(t)
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
-	defer testutil.MustCloseContext(t, conn)
-
 		in := &pgtype.Timestamptz{Time: time.Date(294276, 12, 31, 23, 59, 59, 999999000, time.UTC), Valid: true}
 		var out pgtype.Timestamptz
 
-	err := conn.QueryRow(context.Background(), "select $1::timestamptz", in).Scan(&out)
+		err := conn.QueryRow(ctx, "select $1::timestamptz", in).Scan(&out)
 		if err != nil {
 			t.Fatal(err)
 		}
 
 		require.Equal(t, in.Valid, out.Valid)
 		require.Truef(t, in.Time.Equal(out.Time), "expected %v got %v", in.Time, out.Time)
+	})
 }
 
 // https://github.com/jackc/pgtype/issues/74

pgtype/uint32_test.go

@@ -1,14 +1,15 @@
 package pgtype_test
 
 import (
+	"context"
 	"testing"
 
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func TestUint32Codec(t *testing.T) {
-	testutil.RunTranscodeTests(t, "oid", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, pgxtest.KnownOIDQueryExecModes, "oid", []pgxtest.ValueRoundTripTest{
 		{
 			pgtype.Uint32{Uint32: pgtype.TextOID, Valid: true},
 			new(pgtype.Uint32),

pgtype/uuid_test.go

@@ -1,31 +1,22 @@
 package pgtype_test
 
 import (
+	"context"
 	"reflect"
 	"testing"
 
 	"github.com/jackc/pgx/v5/pgtype"
-	"github.com/jackc/pgx/v5/pgtype/testutil"
+	"github.com/jackc/pgx/v5/pgxtest"
 	"github.com/stretchr/testify/require"
 )
 
 func TestUUIDCodec(t *testing.T) {
-	testutil.RunTranscodeTests(t, "uuid", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "uuid", []pgxtest.ValueRoundTripTest{
 		{
 			pgtype.UUID{Bytes: [16]byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}, Valid: true},
 			new(pgtype.UUID),
 			isExpectedEq(pgtype.UUID{Bytes: [16]byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}, Valid: true}),
 		},
-		{
-			[16]byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
-			new(pgtype.UUID),
-			isExpectedEq(pgtype.UUID{Bytes: [16]byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}, Valid: true}),
-		},
-		{
-			[]byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
-			new(pgtype.UUID),
-			isExpectedEq(pgtype.UUID{Bytes: [16]byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}, Valid: true}),
-		},
 		{
 			"00010203-0405-0607-0809-0a0b0c0d0e0f",
 			new(pgtype.UUID),
@@ -40,6 +31,19 @@ func TestUUIDCodec(t *testing.T) {
 		{pgtype.UUID{}, new(pgtype.UUID), isExpectedEq(pgtype.UUID{})},
 		{nil, new(pgtype.UUID), isExpectedEq(pgtype.UUID{})},
 	})
+
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, pgxtest.KnownOIDQueryExecModes, "uuid", []pgxtest.ValueRoundTripTest{
+		{
+			[16]byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
+			new(pgtype.UUID),
+			isExpectedEq(pgtype.UUID{Bytes: [16]byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}, Valid: true}),
+		},
+		{
+			[]byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
+			new(pgtype.UUID),
+			isExpectedEq(pgtype.UUID{Bytes: [16]byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}, Valid: true}),
+		},
+	})
 }
 
 func TestUUID_MarshalJSON(t *testing.T) {

pgtype/zeronull/float8_test.go

@@ -1,10 +1,11 @@
 package zeronull_test
 
 import (
+	"context"
 	"testing"
 
-	"github.com/jackc/pgx/v5/pgtype/testutil"
 	"github.com/jackc/pgx/v5/pgtype/zeronull"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func isExpectedEq(a interface{}) func(interface{}) bool {
@@ -14,7 +15,7 @@ func isExpectedEq(a interface{}) func(interface{}) bool {
 }
 
 func TestFloat8Transcode(t *testing.T) {
-	testutil.RunTranscodeTests(t, "float8", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "float8", []pgxtest.ValueRoundTripTest{
 		{
 			(zeronull.Float8)(1),
 			new(zeronull.Float8),

pgtype/zeronull/int_test.go

@@ -2,14 +2,15 @@
 package zeronull_test
 
 import (
+	"context"
 	"testing"
 
-	"github.com/jackc/pgx/v5/pgtype/testutil"
 	"github.com/jackc/pgx/v5/pgtype/zeronull"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func TestInt2Transcode(t *testing.T) {
-	testutil.RunTranscodeTests(t, "int2", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "int2", []pgxtest.ValueRoundTripTest{
 		{
 			(zeronull.Int2)(1),
 			new(zeronull.Int2),
@@ -29,7 +30,7 @@ func TestInt2Transcode(t *testing.T) {
 }
 
 func TestInt4Transcode(t *testing.T) {
-	testutil.RunTranscodeTests(t, "int4", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "int4", []pgxtest.ValueRoundTripTest{
 		{
 			(zeronull.Int4)(1),
 			new(zeronull.Int4),
@@ -49,7 +50,7 @@ func TestInt4Transcode(t *testing.T) {
 }
 
 func TestInt8Transcode(t *testing.T) {
-	testutil.RunTranscodeTests(t, "int8", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "int8", []pgxtest.ValueRoundTripTest{
 		{
 			(zeronull.Int8)(1),
 			new(zeronull.Int8),

pgtype/zeronull/int_test.go.erb

@@ -10,7 +10,7 @@ import (
 <% [2, 4, 8].each do |pg_byte_size| %>
 <% pg_bit_size = pg_byte_size * 8 %>
 func TestInt<%= pg_byte_size %>Transcode(t *testing.T) {
-	testutil.RunTranscodeTests(t, "int<%= pg_byte_size %>", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "int<%= pg_byte_size %>", []pgxtest.ValueRoundTripTest{
 		{
 			(zeronull.Int<%= pg_byte_size %>)(1),
 			new(zeronull.Int<%= pg_byte_size %>),

pgtype/zeronull/text_test.go

@@ -1,14 +1,15 @@
 package zeronull_test
 
 import (
+	"context"
 	"testing"
 
-	"github.com/jackc/pgx/v5/pgtype/testutil"
 	"github.com/jackc/pgx/v5/pgtype/zeronull"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func TestTextTranscode(t *testing.T) {
-	testutil.RunTranscodeTests(t, "text", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "text", []pgxtest.ValueRoundTripTest{
 		{
 			(zeronull.Text)("foo"),
 			new(zeronull.Text),

pgtype/zeronull/timestamp_test.go

@@ -1,11 +1,12 @@
 package zeronull_test
 
 import (
+	"context"
 	"testing"
 	"time"
 
-	"github.com/jackc/pgx/v5/pgtype/testutil"
 	"github.com/jackc/pgx/v5/pgtype/zeronull"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func isExpectedEqTimestamp(a interface{}) func(interface{}) bool {
@@ -18,7 +19,7 @@ func isExpectedEqTimestamp(a interface{}) func(interface{}) bool {
 }
 
 func TestTimestampTranscode(t *testing.T) {
-	testutil.RunTranscodeTests(t, "timestamp", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "timestamp", []pgxtest.ValueRoundTripTest{
 		{
 			(zeronull.Timestamp)(time.Date(2020, 1, 1, 0, 0, 0, 0, time.UTC)),
 			new(zeronull.Timestamp),

pgtype/zeronull/timestamptz_test.go

@@ -1,11 +1,12 @@
 package zeronull_test
 
 import (
+	"context"
 	"testing"
 	"time"
 
-	"github.com/jackc/pgx/v5/pgtype/testutil"
 	"github.com/jackc/pgx/v5/pgtype/zeronull"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func isExpectedEqTimestamptz(a interface{}) func(interface{}) bool {
@@ -18,7 +19,7 @@ func isExpectedEqTimestamptz(a interface{}) func(interface{}) bool {
 }
 
 func TestTimestamptzTranscode(t *testing.T) {
-	testutil.RunTranscodeTests(t, "timestamptz", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "timestamptz", []pgxtest.ValueRoundTripTest{
 		{
 			(zeronull.Timestamptz)(time.Date(2020, 1, 1, 0, 0, 0, 0, time.UTC)),
 			new(zeronull.Timestamptz),

pgtype/zeronull/uuid_test.go

@@ -1,14 +1,15 @@
 package zeronull_test
 
 import (
+	"context"
 	"testing"
 
-	"github.com/jackc/pgx/v5/pgtype/testutil"
 	"github.com/jackc/pgx/v5/pgtype/zeronull"
+	"github.com/jackc/pgx/v5/pgxtest"
 )
 
 func TestUUIDTranscode(t *testing.T) {
-	testutil.RunTranscodeTests(t, "uuid", []testutil.TranscodeTestCase{
+	pgxtest.RunValueRoundTripTests(context.Background(), t, defaultConnTestRunner, nil, "uuid", []pgxtest.ValueRoundTripTest{
 		{
 			(zeronull.UUID)([16]byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}),
 			new(zeronull.UUID),

pgtype/zeronull/zeronull.go

@@ -0,0 +1,17 @@
+package zeronull
+
+import (
+	"github.com/jackc/pgx/v5/pgtype"
+)
+
+// Register registers the zeronull types so they can be used in query exec modes that do not know the server OIDs.
+func Register(m *pgtype.Map) {
+	m.RegisterDefaultPgType(Float8(0), "float8")
+	m.RegisterDefaultPgType(Int2(0), "int2")
+	m.RegisterDefaultPgType(Int4(0), "int4")
+	m.RegisterDefaultPgType(Int8(0), "int8")
+	m.RegisterDefaultPgType(Text(""), "text")
+	m.RegisterDefaultPgType(Timestamp{}, "timestamp")
+	m.RegisterDefaultPgType(Timestamptz{}, "timestamptz")
+	m.RegisterDefaultPgType(UUID{}, "uuid")
+}

pgtype/zeronull/zeronull_test.go

@@ -0,0 +1,26 @@
+package zeronull_test
+
+import (
+	"context"
+	"os"
+	"testing"
+
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgtype/zeronull"
+	"github.com/jackc/pgx/v5/pgxtest"
+	"github.com/stretchr/testify/require"
+)
+
+var defaultConnTestRunner pgxtest.ConnTestRunner
+
+func init() {
+	defaultConnTestRunner = pgxtest.DefaultConnTestRunner()
+	defaultConnTestRunner.CreateConfig = func(ctx context.Context, t testing.TB) *pgx.ConnConfig {
+		config, err := pgx.ParseConfig(os.Getenv("PGX_TEST_DATABASE"))
+		require.NoError(t, err)
+		return config
+	}
+	defaultConnTestRunner.AfterConnect = func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
+		zeronull.Register(conn.TypeMap())
+	}
+}

pgxtest/pgxtest.go

@@ -3,11 +3,28 @@ package pgxtest
 
 import (
 	"context"
+	"fmt"
+	"reflect"
 	"testing"
 
 	"github.com/jackc/pgx/v5"
 )
 
+var AllQueryExecModes = []pgx.QueryExecMode{
+	pgx.QueryExecModeCacheStatement,
+	pgx.QueryExecModeCacheDescribe,
+	pgx.QueryExecModeDescribeExec,
+	pgx.QueryExecModeExec,
+	pgx.QueryExecModeSimpleProtocol,
+}
+
+// KnownOIDQueryExecModes is a slice of all query exec modes where the param and result OIDs are known before sending the query.
+var KnownOIDQueryExecModes = []pgx.QueryExecMode{
+	pgx.QueryExecModeCacheStatement,
+	pgx.QueryExecModeCacheDescribe,
+	pgx.QueryExecModeDescribeExec,
+}
+
 // ConnTestRunner controls how a *pgx.Conn is created and closed by tests. All fields are required. Use DefaultConnTestRunner to get a
 // ConnTestRunner with reasonable default values.
 type ConnTestRunner struct {
@@ -46,6 +63,8 @@ func DefaultConnTestRunner() ConnTestRunner {
 }
 
 func (ctr *ConnTestRunner) RunTest(ctx context.Context, t testing.TB, f func(ctx context.Context, t testing.TB, conn *pgx.Conn)) {
+	t.Helper()
+
 	config := ctr.CreateConfig(ctx, t)
 	conn, err := pgx.ConnectConfig(ctx, config)
 	if err != nil {
@@ -62,13 +81,7 @@ func (ctr *ConnTestRunner) RunTest(ctx context.Context, t testing.TB, f func(ctx
 // If modes is nil all pgx.QueryExecModes are tested.
 func RunWithQueryExecModes(ctx context.Context, t *testing.T, ctr ConnTestRunner, modes []pgx.QueryExecMode, f func(ctx context.Context, t testing.TB, conn *pgx.Conn)) {
 	if modes == nil {
-		modes = []pgx.QueryExecMode{
+		modes = AllQueryExecModes
-			pgx.QueryExecModeCacheStatement,
-			pgx.QueryExecModeCacheDescribe,
-			pgx.QueryExecModeDescribeExec,
-			pgx.QueryExecModeExec,
-			pgx.QueryExecModeSimpleProtocol,
-		}
 	}
 
 	for _, mode := range modes {
@@ -87,6 +100,51 @@ func RunWithQueryExecModes(ctx context.Context, t *testing.T, ctr ConnTestRunner
 	}
 }
 
+type ValueRoundTripTest struct {
+	Param  interface{}
+	Result interface{}
+	Test   func(interface{}) bool
+}
+
+func RunValueRoundTripTests(
+	ctx context.Context,
+	t testing.TB,
+	ctr ConnTestRunner,
+	modes []pgx.QueryExecMode,
+	pgTypeName string,
+	tests []ValueRoundTripTest,
+) {
+	t.Helper()
+
+	if modes == nil {
+		modes = AllQueryExecModes
+	}
+
+	ctr.RunTest(ctx, t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
+		t.Helper()
+
+		sql := fmt.Sprintf("select $1::%s", pgTypeName)
+
+		for i, tt := range tests {
+			for _, mode := range modes {
+				err := conn.QueryRow(ctx, sql, mode, tt.Param).Scan(tt.Result)
+				if err != nil {
+					t.Errorf("%d. %v: %v", i, mode, err)
+				}
+
+				result := reflect.ValueOf(tt.Result)
+				if result.Kind() == reflect.Ptr {
+					result = result.Elem()
+				}
+
+				if !tt.Test(result.Interface()) {
+					t.Errorf("%d. %v: unexpected result for %v: %v", i, mode, tt.Param, result.Interface())
+				}
+			}
+		}
+	})
+}
+
 // SkipCockroachDB calls Skip on t with msg if the connection is to a CockroachDB server.
 func SkipCockroachDB(t testing.TB, conn *pgx.Conn, msg string) {
 	if conn.PgConn().ParameterStatus("crdb_version") != "" {

values.go

@@ -17,7 +17,7 @@ func convertSimpleArgument(m *pgtype.Map, arg interface{}) (interface{}, error)
 		return nil, nil
 	}
 
-	buf, err := m.Encode(0, TextFormatCode, arg, nil)
+	buf, err := m.Encode(0, TextFormatCode, arg, []byte{})
 	if err != nil {
 		return nil, err
 	}