Add CallFunctionWithRows() for help testing calls to QueryChunks

examples/example_service/example_service_test.go

@@ -5,7 +5,6 @@ import (
 	"testing"
 
 	gomock "github.com/golang/mock/gomock"
-	"github.com/stretchr/testify/require"
 	"github.com/tj/assert"
 	"github.com/vingarcia/ksql"
 	"github.com/vingarcia/ksql/nullable"
@@ -198,19 +197,17 @@ func TestStreamAllUsers(t *testing.T) {
 
 		mockDB.EXPECT().QueryChunks(gomock.Any(), gomock.Any()).
 			DoAndReturn(func(ctx context.Context, parser ksql.ChunkParser) error {
-				fn, ok := parser.ForEachChunk.(func(users []UserEntity) error)
-				require.True(t, ok)
 				// Chunk 1:
-				err := fn([]UserEntity{
+				err := ksql.CallFunctionWithRows(parser.ForEachChunk, []map[string]interface{}{
 					{
-						ID:   1,
-						Name: nullable.String("fake name"),
-						Age:  nullable.Int(42),
+						"id":   1,
+						"name": "fake name",
+						"age":  42,
 					},
 					{
-						ID:   2,
-						Name: nullable.String("another fake name"),
-						Age:  nullable.Int(43),
+						"id":   2,
+						"name": "another fake name",
+						"age":  43,
 					},
 				})
 				if err != nil {
@@ -218,11 +215,11 @@ func TestStreamAllUsers(t *testing.T) {
 				}
 
 				// Chunk 2:
-				err = fn([]UserEntity{
+				err = ksql.CallFunctionWithRows(parser.ForEachChunk, []map[string]interface{}{
 					{
-						ID:   3,
-						Name: nullable.String("yet another fake name"),
-						Age:  nullable.Int(44),
+						"id":   3,
+						"name": "yet another fake name",
+						"age":  44,
 					},
 				})
 				return err

structs/structs.go

@@ -262,7 +262,7 @@ func FillSliceWith(entities interface{}, dbRows []map[string]interface{}) error
 	sliceType := sliceRef.Type()
 	if sliceType.Kind() != reflect.Ptr {
 		return fmt.Errorf(
-			"FillSliceWith: expected input to be a pointer to struct but got %v",
+			"FillSliceWith: expected input to be a pointer to a slice of structs but got %v",
 			sliceType,
 		)
 	}

test_helpers.go

@@ -0,0 +1,31 @@
+package ksql
+
+import (
+	"reflect"
+
+	"github.com/vingarcia/ksql/structs"
+)
+
+// CallFunctionWithRows was created for helping test the QueryChunks method
+func CallFunctionWithRows(fn interface{}, rows []map[string]interface{}) error {
+	fnValue := reflect.ValueOf(fn)
+	chunkType, err := parseInputFunc(fn)
+	if err != nil {
+		return err
+	}
+
+	chunk := reflect.MakeSlice(chunkType, 0, len(rows))
+
+	// Create a pointer to a slice (required by FillSliceWith)
+	chunkPtr := reflect.New(chunkType)
+	chunkPtr.Elem().Set(chunk)
+
+	err = structs.FillSliceWith(chunkPtr.Interface(), rows)
+	if err != nil {
+		return err
+	}
+
+	err, _ = fnValue.Call([]reflect.Value{chunkPtr.Elem()})[0].Interface().(error)
+
+	return err
+}