Improve panic message when ksql.Mock methods are called but unimplemented

mocks.go

@@ -1,6 +1,9 @@
 package ksql
 
-import "context"
+import (
+	"context"
+	"fmt"
+)
 
 var _ Provider = Mock{}
 
@@ -20,40 +23,64 @@ type Mock struct {
 
 // Insert ...
 func (m Mock) Insert(ctx context.Context, table Table, record interface{}) error {
+	if m.InsertFn == nil {
+		panic(fmt.Errorf("Mock.Insert(ctx, %v, %v) called but the ksql.Mock.InsertFn() is not set", table, record))
+	}
 	return m.InsertFn(ctx, table, record)
 }
 
 // Update ...
 func (m Mock) Update(ctx context.Context, table Table, record interface{}) error {
+	if m.UpdateFn == nil {
+		panic(fmt.Errorf("Mock.Update(ctx, %v, %v) called but the ksql.Mock.UpdateFn() is not set", table, record))
+	}
 	return m.UpdateFn(ctx, table, record)
 }
 
 // Delete ...
 func (m Mock) Delete(ctx context.Context, table Table, ids ...interface{}) error {
+	if m.DeleteFn == nil {
+		panic(fmt.Errorf("Mock.Delete(ctx, %v, %v) called but the ksql.Mock.DeleteFn() is not set", table, ids))
+	}
 	return m.DeleteFn(ctx, table, ids...)
 }
 
 // Query ...
 func (m Mock) Query(ctx context.Context, records interface{}, query string, params ...interface{}) error {
+	if m.QueryFn == nil {
+		panic(fmt.Errorf("Mock.Query(ctx, %v, %s, %v) called but the ksql.Mock.QueryFn() is not set", records, query, params))
+	}
 	return m.QueryFn(ctx, records, query, params...)
 }
 
 // QueryOne ...
 func (m Mock) QueryOne(ctx context.Context, record interface{}, query string, params ...interface{}) error {
+	if m.QueryOneFn == nil {
+		panic(fmt.Errorf("Mock.QueryOne(ctx, %v, %s, %v) called but the ksql.Mock.QueryOneFn() is not set", record, query, params))
+	}
 	return m.QueryOneFn(ctx, record, query, params...)
 }
 
 // QueryChunks ...
 func (m Mock) QueryChunks(ctx context.Context, parser ChunkParser) error {
+	if m.QueryChunksFn == nil {
+		panic(fmt.Errorf("Mock.QueryChunks(ctx, %v) called but the ksql.Mock.QueryChunksFn() is not set", parser))
+	}
 	return m.QueryChunksFn(ctx, parser)
 }
 
 // Exec ...
 func (m Mock) Exec(ctx context.Context, query string, params ...interface{}) error {
+	if m.ExecFn == nil {
+		panic(fmt.Errorf("Mock.Exec(ctx, %s, %v) called but the ksql.Mock.ExecFn() is not set", query, params))
+	}
 	return m.ExecFn(ctx, query, params...)
 }
 
 // Transaction ...
 func (m Mock) Transaction(ctx context.Context, fn func(db Provider) error) error {
+	if m.TransactionFn == nil {
+		return fn(m)
+	}
 	return m.TransactionFn(ctx, fn)
 }