Testing around MSSQL table-valued parameters in sqlmock - sql-server

Question

I have a function that is designed to insert a large number of elements into an MSSQL database using a table-valued parameter and a procedure.
func (requester *Requester) doQuery(ctx context.Context, dtos interface{}) error {
conn, err := requester.conn.Conn(ctx)
if err != nil {
return err
}
defer func() {
if clErr := conn.Close(); clErr != nil {
err = clErr
}
}()
tx, err := conn.BeginTx(ctx, &sql.TxOptions{Isolation: sql.LevelRepeatableRead, ReadOnly: false})
if err != nil {
return err
}
defer func() {
if p := recover(); p != nil {
tx.Rollback()
panic(p)
} else if err != nil {
tx.Rollback()
} else {
tx.Commit()
}()
param := sql.Named("TVP", mssql.TVP{
TypeName: "MyTypeName",
Value: dtos,
})
return tx.ExecContext(ctx, "EXEC [dbo].[usp_InsertConsumption] #TVP", param)
}
The test I wrote for this function is included below (note that it depends on ginkgo and gomega):
Describe("SQL Tests", func() {
It("AddConsumption - No failures - Added", func() {
db, mock, _ := sqlmock.New()
requester := Requester{conn: db}
defer db.Close()
mock.ExpectBegin()
mock.ExpectExec(regexp.QuoteMeta("EXEC [dbo].[usp_InsertConsumption] #TVP")).
WithArgs("").WillReturnResult(sqlmock.NewResult(1, 1))
mock.ExpectExec(regexp.QuoteMeta("EXEC [dbo].[usp_InsertTags] #TVP")).
WithArgs("").WillReturnResult(sqlmock.NewResult(1, 1))
mock.ExpectCommit()
err := requester.doQuery(context.TODO(), generateData())
Expect(err).ShouldNot(HaveOccurred())
Expect(mock.ExpectationsWereMet()).ShouldNot(HaveOccurred())
})
})
Now, this code was written for a MySQL context and since I've ported the code over to MSSQL, I've been getting a peculiar error:
sql: converting argument with name \"TVP\" type: unsupported type mssql.TVP, a struct
It appears that sqlmock is attempting to call ConvertValue on the TVP object, which is invalid. So, how do I make sqlmock handle this value correctly so I can unit test around the query?

Answer 1

What I discovered here is that sqlmock has a function called ValueConverterOption, which, when provided with a custom driver.ValueConverter interface. This will be called in place of the standard function for every invocation of ConvertValue. If you want to test around the ExecContext function when it receives a non-standard argument, a TVP in this case, then you can use this function to inject custom conversion logic into sqlmock.
type mockTvpConverter struct {}
func (converter *mockTvpConverter) ConvertValue(raw interface{}) (driver.Value, error) {
// Since this function will take the place of every call of ConvertValue, we will inevitably
// the fake string we return from this function so we need to check whether we've recieved
// that or a TVP. More extensive logic may be required
switch inner := raw.(type) {
case string:
return raw.(string), nil
case mssql.TVP:
// First, verify the type name
Expect(inner.TypeName).Should(Equal("MyTypeName"))
// VERIFICATION LOGIC HERE
// Finally, return a fake value that we can use when verifying the arguments
return "PASSED", nil
}
// We had an invalid type; return an error
return nil, fmt.Errorf("Invalid type")
}
which means, the test then becomes:
Describe("SQL Tests", func() {
It("AddConsumption - No failures - Added", func() {
db, mock, _ := sqlmock.New(sqlmock.ValueConverterOption(&mockTvpConverter{}))
requester := Requester{conn: db}
defer db.Close()
mock.ExpectBegin()
mock.ExpectExec(regexp.QuoteMeta("EXEC [dbo].[usp_InsertConsumption] #TVP")).
WithArgs("PASSED").WillReturnResult(sqlmock.NewResult(1, 1))
mock.ExpectExec(regexp.QuoteMeta("EXEC [dbo].[usp_InsertTags] #TVP")).
WithArgs("PASSED").WillReturnResult(sqlmock.NewResult(1, 1))
mock.ExpectCommit()
err := requester.doQuery(context.TODO(), generateData())
Expect(err).ShouldNot(HaveOccurred())
Expect(mock.ExpectationsWereMet()).ShouldNot(HaveOccurred())
})
})