Merge d630799e906b41467a47b801ec24b892e71a47e0 into 0a51f6cdc55d1650d9ed3b4c13026cfa9133b01e

2017-11-26 07:14:44 +00:00 · 2017-11-26 07:14:44 +00:00 · 3087813925
commit 3087813925
parent 0a51f6cdc5 d630799e90
7 changed files with 1076 additions and 0 deletions
--- a/callback_query_preload.go
+++ b/callback_query_preload.go
@ -60,6 +60,7 @@ func preloadCallback(scope *Scope) {
 						currentScope.handleBelongsToPreload(field, currentPreloadConditions)
 					case "many_to_many":
 						currentScope.handleManyToManyPreload(field, currentPreloadConditions)
+
 					default:
 						scope.Err(errors.New("unsupported relation"))
 					}
@ -264,6 +265,8 @@ func (scope *Scope) handleBelongsToPreload(field *Field, conditions []interface{

 // handleManyToManyPreload used to preload many to many associations
 func (scope *Scope) handleManyToManyPreload(field *Field, conditions []interface{}) {
+	// spew.Println("___ENTERING HANDLE MANY TO MANY___\r\n")
+	// spew.Printf("___POPULATING %s___:\r\n%s\r\n", field.Name, spew.Sdump(field))
 	var (
 		relation         = field.Relationship
 		joinTableHandler = relation.JoinTableHandler
@ -303,6 +306,7 @@ func (scope *Scope) handleManyToManyPreload(field *Field, conditions []interface
 	}

 	rows, err := preloadDB.Rows()
+	// spew.Printf("___RETURNED ROWS___: \r\n%s\r\n", spew.Sdump(rows))

 	if scope.Err(err) != nil {
 		return
@ -312,6 +316,7 @@ func (scope *Scope) handleManyToManyPreload(field *Field, conditions []interface
 	columns, _ := rows.Columns()
 	for rows.Next() {
 		var (
+			// This is a Language zero value struct
 			elem   = reflect.New(fieldType).Elem()
 			fields = scope.New(elem.Addr().Interface()).Fields()
 		)
@ -323,6 +328,7 @@ func (scope *Scope) handleManyToManyPreload(field *Field, conditions []interface
 		}

 		scope.scan(rows, columns, append(fields, joinTableFields...))
+		// spew.Printf("___FIELDS___: \r\n%s\r\n", spew.Sdump(fields))

 		var foreignKeys = make([]interface{}, len(sourceKeys))
 		// generate hashed forkey keys in join table
@ -351,12 +357,14 @@ func (scope *Scope) handleManyToManyPreload(field *Field, conditions []interface
 		foreignFieldNames  = []string{}
 	)

+	// spew.Printf("Foreign fields: %s", spew.Sdump(relation.ForeignFieldNames))
 	for _, dbName := range relation.ForeignFieldNames {
 		if field, ok := scope.FieldByName(dbName); ok {
 			foreignFieldNames = append(foreignFieldNames, field.Name)
 		}
 	}

+	// spew.Printf("Scope value: %s", spew.Sdump(indirectScopeValue))
 	if indirectScopeValue.Kind() == reflect.Slice {
 		for j := 0; j < indirectScopeValue.Len(); j++ {
 			object := indirect(indirectScopeValue.Index(j))
@ -367,6 +375,9 @@ func (scope *Scope) handleManyToManyPreload(field *Field, conditions []interface
 		key := toString(getValueFromFields(indirectScopeValue, foreignFieldNames))
 		fieldsSourceMap[key] = append(fieldsSourceMap[key], indirectScopeValue.FieldByName(field.Name))
 	}
+
+	// spew.Printf("Field source map: %s", spew.Sdump(fieldsSourceMap))
+	// spew.Printf("Link hash: %s", spew.Sdump(linkHash))
 	for source, link := range linkHash {
 		for i, field := range fieldsSourceMap[source] {
 			//If not 0 this means Value is a pointer and we already added preloaded models to it
--- a/expecter.go
+++ b/expecter.go
@ -0,0 +1,225 @@
+package gorm
+
+import (
+	"fmt"
+)
+
+// Recorder satisfies the logger interface
+type Recorder struct {
+	stmts   []Stmt
+	preload []searchPreload // store it on Recorder
+}
+
+// Stmt represents a sql statement. It can be an Exec, Query, or QueryRow
+type Stmt struct {
+	kind    string // can be Query, Exec, QueryRow
+	preload string // contains schema if it is a preload query
+	sql     string
+	args    []interface{}
+}
+
+func recordExecCallback(scope *Scope) {
+	r, ok := scope.Get("gorm:recorder")
+
+	if !ok {
+		panic(fmt.Errorf("Expected a recorder to be set, but got none"))
+	}
+
+	stmt := Stmt{
+		kind: "exec",
+		sql:  scope.SQL,
+		args: scope.SQLVars,
+	}
+
+	recorder := r.(*Recorder)
+
+	recorder.Record(stmt)
+}
+
+func recordQueryCallback(scope *Scope) {
+	r, ok := scope.Get("gorm:recorder")
+
+	if !ok {
+		panic(fmt.Errorf("Expected a recorder to be set, but got none"))
+	}
+
+	recorder := r.(*Recorder)
+
+	stmt := Stmt{
+		kind: "query",
+		sql:  scope.SQL,
+		args: scope.SQLVars,
+	}
+
+	if len(recorder.preload) > 0 {
+		// this will cause the scope.SQL to mutate to the preload query
+		stmt.preload = recorder.preload[0].schema
+
+		// we just want to pop the first element off
+		recorder.preload = recorder.preload[1:]
+	}
+
+	recorder.Record(stmt)
+}
+
+func recordPreloadCallback(scope *Scope) {
+	// this callback runs _before_ gorm:preload
+	// it should record the next thing to be preloaded
+	recorder, ok := scope.Get("gorm:recorder")
+
+	if !ok {
+		panic(fmt.Errorf("Expected a recorder to be set, but got none"))
+	}
+
+	if len(scope.Search.preload) > 0 {
+		// spew.Printf("callback:preload\r\n%s\r\n", spew.Sdump(scope.Search.preload))
+		recorder.(*Recorder).preload = scope.Search.preload
+	}
+}
+
+// Record records a Stmt for use when SQL is finally executed
+func (r *Recorder) Record(stmt Stmt) {
+	r.stmts = append(r.stmts, stmt)
+}
+
+// GetFirst returns the first recorded sql statement logged. If there are no
+// statements, false is returned
+func (r *Recorder) GetFirst() (Stmt, bool) {
+	var stmt Stmt
+	if len(r.stmts) > 0 {
+		stmt = r.stmts[0]
+		return stmt, true
+	}
+
+	return stmt, false
+}
+
+// IsEmpty returns true if the statements slice is empty
+func (r *Recorder) IsEmpty() bool {
+	return len(r.stmts) == 0
+}
+
+// AdapterFactory is a generic interface for arbitrary adapters that satisfy
+// the interface. variadic args are passed to gorm.Open.
+type AdapterFactory func(dialect string, args ...interface{}) (*DB, Adapter, error)
+
+// Expecter is the exported struct used for setting expectations
+type Expecter struct {
+	// globally scoped expecter
+	adapter  Adapter
+	gorm     *DB
+	recorder *Recorder
+}
+
+// NewDefaultExpecter returns a Expecter powered by go-sqlmock
+func NewDefaultExpecter() (*DB, *Expecter, error) {
+	gormDb, adapter, err := NewSqlmockAdapter("sqlmock", "mock_gorm_dsn")
+
+	if err != nil {
+		return nil, nil, err
+	}
+
+	recorder := &Recorder{}
+	noop, _ := NewNoopDB()
+	gorm := &DB{
+		db:        noop,
+		logger:    defaultLogger,
+		values:    map[string]interface{}{},
+		callbacks: DefaultCallback,
+		dialect:   newDialect("sqlmock", noop),
+	}
+
+	gorm.parent = gorm
+	gorm = gorm.Set("gorm:recorder", recorder)
+	gorm.Callback().Create().After("gorm:create").Register("gorm:record_exec", recordExecCallback)
+	gorm.Callback().Query().Before("gorm:preload").Register("gorm:record_preload", recordPreloadCallback)
+	gorm.Callback().Query().After("gorm:query").Register("gorm:record_query", recordQueryCallback)
+	gorm.Callback().RowQuery().After("gorm:row_query").Register("gorm:record_query", recordQueryCallback)
+	gorm.Callback().Update().After("gorm:update").Register("gorm:record_exec", recordExecCallback)
+
+	return gormDb, &Expecter{adapter: adapter, gorm: gorm, recorder: recorder}, nil
+}
+
+// NewExpecter returns an Expecter for arbitrary adapters
+func NewExpecter(fn AdapterFactory, dialect string, args ...interface{}) (*DB, *Expecter, error) {
+	gormDb, adapter, err := fn(dialect, args...)
+
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return gormDb, &Expecter{adapter: adapter}, nil
+}
+
+/* PUBLIC METHODS */
+
+// AssertExpectations checks if all expected Querys and Execs were satisfied.
+func (h *Expecter) AssertExpectations() error {
+	return h.adapter.AssertExpectations()
+}
+
+// Model sets scope.Value
+func (h *Expecter) Model(model interface{}) *Expecter {
+	h.gorm = h.gorm.Model(model)
+	return h
+}
+
+/* CREATE */
+
+// Create mocks insertion of a model into the DB
+func (h *Expecter) Create(model interface{}) ExpectedExec {
+	h.gorm.Create(model)
+	return h.adapter.ExpectExec(h.recorder.stmts[0])
+}
+
+/* READ */
+
+// First triggers a Query
+func (h *Expecter) First(out interface{}, where ...interface{}) ExpectedQuery {
+	h.gorm.First(out, where...)
+	return h.adapter.ExpectQuery(h.recorder.stmts...)
+}
+
+// Find triggers a Query
+func (h *Expecter) Find(out interface{}, where ...interface{}) ExpectedQuery {
+	h.gorm.Find(out, where...)
+	return h.adapter.ExpectQuery(h.recorder.stmts...)
+}
+
+// Preload clones the expecter and sets a preload condition on gorm.DB
+func (h *Expecter) Preload(column string, conditions ...interface{}) *Expecter {
+	clone := h.clone()
+	clone.gorm = clone.gorm.Preload(column, conditions...)
+
+	return clone
+}
+
+/* UPDATE */
+
+// Save mocks updating a record in the DB and will trigger db.Exec()
+func (h *Expecter) Save(model interface{}) ExpectedExec {
+	h.gorm.Save(model)
+	return h.adapter.ExpectExec(h.recorder.stmts[0])
+}
+
+// Update mocks updating the given attributes in the DB
+func (h *Expecter) Update(attrs ...interface{}) ExpectedExec {
+	h.gorm.Update(attrs...)
+	return h.adapter.ExpectExec(h.recorder.stmts[0])
+}
+
+// Updates does the same thing as Update, but with map or struct
+func (h *Expecter) Updates(values interface{}, ignoreProtectedAttrs ...bool) ExpectedExec {
+	h.gorm.Updates(values, ignoreProtectedAttrs...)
+	return h.adapter.ExpectExec(h.recorder.stmts[0])
+}
+
+/* PRIVATE METHODS */
+
+func (h *Expecter) clone() *Expecter {
+	return &Expecter{
+		adapter:  h.adapter,
+		gorm:     h.gorm,
+		recorder: h.recorder,
+	}
+}
--- a/expecter_adapter.go
+++ b/expecter_adapter.go
@ -0,0 +1,68 @@
+package gorm
+
+import (
+	"database/sql"
+
+	sqlmock "gopkg.in/DATA-DOG/go-sqlmock.v1"
+)
+
+var (
+	db   *sql.DB
+	mock sqlmock.Sqlmock
+)
+
+func init() {
+	var err error
+
+	db, mock, err = sqlmock.NewWithDSN("mock_gorm_dsn")
+
+	if err != nil {
+		panic(err.Error())
+	}
+}
+
+// Adapter provides an abstract interface over concrete mock database
+// implementations (e.g. go-sqlmock or go-testdb)
+type Adapter interface {
+	ExpectQuery(stmts ...Stmt) ExpectedQuery
+	ExpectExec(stmt Stmt) ExpectedExec
+	AssertExpectations() error
+}
+
+// SqlmockAdapter implemenets the Adapter interface using go-sqlmock
+// it is the default Adapter
+type SqlmockAdapter struct {
+	db     *sql.DB
+	mocker sqlmock.Sqlmock
+}
+
+// NewSqlmockAdapter returns a mock gorm.DB and an Adapter backed by
+// go-sqlmock
+func NewSqlmockAdapter(dialect string, args ...interface{}) (*DB, Adapter, error) {
+	gormDb, err := Open("sqlmock", "mock_gorm_dsn")
+
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return gormDb, &SqlmockAdapter{db: db, mocker: mock}, nil
+}
+
+// ExpectQuery wraps the underlying mock method for setting a query
+// expectation. It accepts multiple statements in the event of preloading
+func (a *SqlmockAdapter) ExpectQuery(queries ...Stmt) ExpectedQuery {
+	return &SqlmockQuery{mock: a.mocker, queries: queries}
+}
+
+// ExpectExec wraps the underlying mock method for setting a exec
+// expectation
+func (a *SqlmockAdapter) ExpectExec(exec Stmt) ExpectedExec {
+	return &SqlmockExec{mock: a.mocker, exec: exec}
+}
+
+// AssertExpectations asserts that _all_ expectations for a test have been met
+// and returns an error specifying which have not if there are unmet
+// expectations
+func (a *SqlmockAdapter) AssertExpectations() error {
+	return a.mocker.ExpectationsWereMet()
+}
--- a/expecter_noop.go
+++ b/expecter_noop.go
@ -0,0 +1,186 @@
+package gorm
+
+import (
+	"database/sql"
+	"database/sql/driver"
+	"fmt"
+	"io"
+	"sync"
+)
+
+var pool *NoopDriver
+
+func init() {
+	pool = &NoopDriver{
+		conns: make(map[string]*NoopConnection),
+	}
+
+	sql.Register("noop", pool)
+}
+
+// NoopDriver implements sql/driver.Driver
+type NoopDriver struct {
+	sync.Mutex
+	counter int
+	conns   map[string]*NoopConnection
+}
+
+// Open implements sql/driver.Driver
+func (d *NoopDriver) Open(dsn string) (driver.Conn, error) {
+	d.Lock()
+	defer d.Unlock()
+
+	c, ok := d.conns[dsn]
+
+	if !ok {
+		return c, fmt.Errorf("No connection available")
+	}
+
+	c.opened++
+	return c, nil
+}
+
+// NoopResult is a noop struct that satisfies sql.Result
+type NoopResult struct{}
+
+// LastInsertId is a noop method for satisfying drive.Result
+func (r NoopResult) LastInsertId() (int64, error) {
+	return 0, nil
+}
+
+// RowsAffected is a noop method for satisfying drive.Result
+func (r NoopResult) RowsAffected() (int64, error) {
+	return 0, nil
+}
+
+// NoopRows implements driver.Rows
+type NoopRows struct {
+	pos int
+}
+
+// Columns implements driver.Rows
+func (r *NoopRows) Columns() []string {
+	return []string{"foo", "bar", "baz", "lol", "kek", "zzz"}
+}
+
+// Close implements driver.Rows
+func (r *NoopRows) Close() error {
+	return nil
+}
+
+// Next implements driver.Rows and alwys returns only one row
+func (r *NoopRows) Next(dest []driver.Value) error {
+	if r.pos == 1 {
+		return io.EOF
+	}
+	cols := []string{"foo", "bar", "baz", "lol", "kek", "zzz"}
+
+	for i, col := range cols {
+		dest[i] = col
+	}
+
+	r.pos++
+
+	return nil
+}
+
+// NoopStmt implements driver.Stmt
+type NoopStmt struct{}
+
+// Close implements driver.Stmt
+func (s *NoopStmt) Close() error {
+	return nil
+}
+
+// NumInput implements driver.Stmt
+func (s *NoopStmt) NumInput() int {
+	return 1
+}
+
+// Exec implements driver.Stmt
+func (s *NoopStmt) Exec(args []driver.Value) (driver.Result, error) {
+	return &NoopResult{}, nil
+}
+
+// Query implements driver.Stmt
+func (s *NoopStmt) Query(args []driver.Value) (driver.Rows, error) {
+	return &NoopRows{}, nil
+}
+
+// NewNoopDB initialises a new DefaultNoopDB
+func NewNoopDB() (SQLCommon, error) {
+	pool.Lock()
+	dsn := fmt.Sprintf("noop_db_%d", pool.counter)
+	pool.counter++
+
+	noop := &NoopConnection{dsn: dsn, drv: pool}
+	pool.conns[dsn] = noop
+	pool.Unlock()
+
+	db, err := noop.open()
+
+	return db, err
+}
+
+// NoopConnection implements sql/driver.Conn
+// for our purposes, the noop connection never returns an error, as we only
+// require it for generating queries. It is necessary because eagerloading
+// will fail if any operation returns an error
+type NoopConnection struct {
+	dsn    string
+	drv    *NoopDriver
+	opened int
+}
+
+func (c *NoopConnection) open() (*sql.DB, error) {
+	db, err := sql.Open("noop", c.dsn)
+
+	if err != nil {
+		return db, err
+	}
+
+	return db, db.Ping()
+}
+
+// Close implements sql/driver.Conn
+func (c *NoopConnection) Close() error {
+	c.drv.Lock()
+	defer c.drv.Unlock()
+
+	c.opened--
+	if c.opened == 0 {
+		delete(c.drv.conns, c.dsn)
+	}
+
+	return nil
+}
+
+// Begin implements sql/driver.Conn
+func (c *NoopConnection) Begin() (driver.Tx, error) {
+	return c, nil
+}
+
+// Exec implements sql/driver.Conn
+func (c *NoopConnection) Exec(query string, args []driver.Value) (driver.Result, error) {
+	return NoopResult{}, nil
+}
+
+// Prepare implements sql/driver.Conn
+func (c *NoopConnection) Prepare(query string) (driver.Stmt, error) {
+	return &NoopStmt{}, nil
+}
+
+// Query implements sql/driver.Conn
+func (c *NoopConnection) Query(query string, args []driver.Value) (driver.Rows, error) {
+	return &NoopRows{}, nil
+}
+
+// Commit implements sql/driver.Conn
+func (c *NoopConnection) Commit() error {
+	return nil
+}
+
+// Rollback implements sql/driver.Conn
+func (c *NoopConnection) Rollback() error {
+	return nil
+}
--- a/expecter_result.go
+++ b/expecter_result.go
@ -0,0 +1,259 @@
+package gorm
+
+import (
+	"database/sql/driver"
+	"fmt"
+	"reflect"
+	"regexp"
+
+	sqlmock "gopkg.in/DATA-DOG/go-sqlmock.v1"
+)
+
+// ExpectedQuery represents an expected query that will be executed and can
+// return some rows. It presents a fluent API for chaining calls to other
+// expectations
+type ExpectedQuery interface {
+	Returns(model interface{}) ExpectedQuery
+}
+
+// ExpectedExec represents an expected exec that will be executed and can
+// return a result. It presents a fluent API for chaining calls to other
+// expectations
+type ExpectedExec interface {
+	WillSucceed(lastInsertID, rowsAffected int64) ExpectedExec
+	WillFail(err error) ExpectedExec
+}
+
+// SqlmockQuery implements Query for go-sqlmock
+type SqlmockQuery struct {
+	mock    sqlmock.Sqlmock
+	queries []Stmt
+	scope   *Scope
+}
+
+func getRowForFields(fields []*Field) []driver.Value {
+	var values []driver.Value
+	for _, field := range fields {
+		if field.IsNormal {
+			value := field.Field
+
+			// dereference pointers
+			if field.Field.Kind() == reflect.Ptr {
+				value = reflect.Indirect(field.Field)
+			}
+
+			// check if we have a zero Value
+			// just append nil if it's not valid, so sqlmock won't complain
+			if !value.IsValid() {
+				values = append(values, nil)
+				continue
+			}
+
+			concreteVal := value.Interface()
+			// spew.Printf("%v: %v\r\n", field.Name, concreteVal)
+
+			if driver.IsValue(concreteVal) {
+				values = append(values, concreteVal)
+			} else if num, err := driver.DefaultParameterConverter.ConvertValue(concreteVal); err == nil {
+				values = append(values, num)
+			} else if valuer, ok := concreteVal.(driver.Valuer); ok {
+				if convertedValue, err := valuer.Value(); err == nil {
+					values = append(values, convertedValue)
+				}
+			}
+		}
+	}
+
+	return values
+}
+
+func (q *SqlmockQuery) getRelationRows(rVal reflect.Value, fieldName string, relation *Relationship) (*sqlmock.Rows, bool) {
+	var (
+		rows    *sqlmock.Rows
+		columns []string
+	)
+
+	// we need to check for zero values
+	if reflect.DeepEqual(rVal.Interface(), reflect.New(rVal.Type()).Elem().Interface()) {
+		// spew.Printf("FOUND EMPTY INTERFACE FOR %s\r\n", fieldName)
+		return nil, false
+	}
+
+	switch relation.Kind {
+	case "has_one":
+		scope := &Scope{Value: rVal.Interface()}
+
+		for _, field := range scope.GetModelStruct().StructFields {
+			if field.IsNormal {
+				columns = append(columns, field.DBName)
+			}
+		}
+
+		rows = sqlmock.NewRows(columns)
+
+		// we don't have a slice
+		row := getRowForFields(scope.Fields())
+		rows = rows.AddRow(row...)
+
+		return rows, true
+	case "has_many":
+		elem := rVal.Type().Elem()
+		scope := &Scope{Value: reflect.New(elem).Interface()}
+
+		for _, field := range scope.GetModelStruct().StructFields {
+			if field.IsNormal {
+				columns = append(columns, field.DBName)
+			}
+		}
+
+		rows = sqlmock.NewRows(columns)
+
+		if rVal.Len() > 0 {
+			for i := 0; i < rVal.Len(); i++ {
+				scope := &Scope{Value: rVal.Index(i).Interface()}
+				row := getRowForFields(scope.Fields())
+				rows = rows.AddRow(row...)
+			}
+
+			return rows, true
+		}
+
+		return nil, false
+	case "many_to_many":
+		elem := rVal.Type().Elem()
+		scope := &Scope{Value: reflect.New(elem).Interface()}
+		joinTable := relation.JoinTableHandler.(*JoinTableHandler)
+
+		for _, field := range scope.GetModelStruct().StructFields {
+			if field.IsNormal {
+				columns = append(columns, field.DBName)
+			}
+		}
+
+		for _, key := range joinTable.Source.ForeignKeys {
+			columns = append(columns, key.DBName)
+		}
+
+		for _, key := range joinTable.Destination.ForeignKeys {
+			columns = append(columns, key.DBName)
+		}
+
+		rows = sqlmock.NewRows(columns)
+
+		// in this case we definitely have a slice
+		if rVal.Len() > 0 {
+			for i := 0; i < rVal.Len(); i++ {
+				scope := &Scope{Value: rVal.Index(i).Interface()}
+				row := getRowForFields(scope.Fields())
+
+				// need to append the values for join table keys
+				sourcePk := q.scope.PrimaryKeyValue()
+				destModelType := joinTable.Destination.ModelType
+				destModelVal := reflect.New(destModelType).Interface()
+				destPkVal := (&Scope{Value: destModelVal}).PrimaryKeyValue()
+
+				row = append(row, sourcePk, destPkVal)
+
+				rows = rows.AddRow(row...)
+			}
+
+			return rows, true
+		}
+
+		return nil, false
+	default:
+		return nil, false
+	}
+}
+
+func (q *SqlmockQuery) getDestRows(out interface{}) *sqlmock.Rows {
+	var columns []string
+	for _, field := range (&Scope{}).New(out).GetModelStruct().StructFields {
+		if field.IsNormal {
+			columns = append(columns, field.DBName)
+		}
+	}
+
+	rows := sqlmock.NewRows(columns)
+	outVal := indirect(reflect.ValueOf(out))
+
+	// SELECT multiple columns
+	if outVal.Kind() == reflect.Slice {
+		outSlice := []interface{}{}
+
+		for i := 0; i < outVal.Len(); i++ {
+			outSlice = append(outSlice, outVal.Index(i).Interface())
+		}
+
+		for _, outElem := range outSlice {
+			scope := &Scope{Value: outElem}
+			row := getRowForFields(scope.Fields())
+			rows = rows.AddRow(row...)
+		}
+	} else if outVal.Kind() == reflect.Struct { // SELECT with LIMIT 1
+		row := getRowForFields(q.scope.Fields())
+		rows = rows.AddRow(row...)
+	} else {
+		panic(fmt.Errorf("Can only get rows for slice or struct"))
+	}
+
+	return rows
+}
+
+// Returns accepts an out type which should either be a struct or slice. Under
+// the hood, it converts a gorm model struct to sql.Rows that can be passed to
+// the underlying mock db
+func (q *SqlmockQuery) Returns(out interface{}) ExpectedQuery {
+	scope := (&Scope{}).New(out)
+	q.scope = scope
+	outVal := indirect(reflect.ValueOf(out))
+
+	// rows := q.getRowsForOutType(out)
+	destQuery := q.queries[0]
+	subQueries := q.queries[1:]
+
+	// main query always at the head of the slice
+	q.mock.ExpectQuery(regexp.QuoteMeta(destQuery.sql)).
+		WillReturnRows(q.getDestRows(out))
+
+	// subqueries are preload
+	for _, subQuery := range subQueries {
+		if subQuery.preload != "" {
+			if field, ok := scope.FieldByName(subQuery.preload); ok {
+				expectation := q.mock.ExpectQuery(regexp.QuoteMeta(subQuery.sql))
+				rows, hasRows := q.getRelationRows(outVal.FieldByName(subQuery.preload), subQuery.preload, field.Relationship)
+
+				if hasRows {
+					expectation.WillReturnRows(rows)
+				}
+			}
+		}
+	}
+
+	return q
+}
+
+// SqlmockExec implements Exec for go-sqlmock
+type SqlmockExec struct {
+	exec  Stmt
+	mock  sqlmock.Sqlmock
+	scope *Scope
+}
+
+// WillSucceed accepts a two int64s. They are passed directly to the underlying
+// mock db. Useful for checking DAO behaviour in the event that the incorrect
+// number of rows are affected by an Exec
+func (e *SqlmockExec) WillSucceed(lastReturnedID, rowsAffected int64) ExpectedExec {
+	result := sqlmock.NewResult(lastReturnedID, rowsAffected)
+	e.mock.ExpectExec(regexp.QuoteMeta(e.exec.sql)).WillReturnResult(result)
+
+	return e
+}
+
+// WillFail simulates returning an Error from an unsuccessful exec
+func (e *SqlmockExec) WillFail(err error) ExpectedExec {
+	result := sqlmock.NewErrorResult(err)
+	e.mock.ExpectExec(regexp.QuoteMeta(e.exec.sql)).WillReturnResult(result)
+
+	return e
+}
--- a/expecter_test.go
+++ b/expecter_test.go
@ -0,0 +1,322 @@
+package gorm_test
+
+import (
+	"errors"
+	"reflect"
+	"testing"
+
+	"github.com/jinzhu/gorm"
+)
+
+func TestNewDefaultExpecter(t *testing.T) {
+	db, _, err := gorm.NewDefaultExpecter()
+	//lint:ignore SA5001 just a mock
+	defer db.Close()
+
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestNewCustomExpecter(t *testing.T) {
+	db, _, err := gorm.NewExpecter(gorm.NewSqlmockAdapter, "sqlmock", "mock_gorm_dsn")
+	//lint:ignore SA5001 just a mock
+	defer db.Close()
+
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestQuery(t *testing.T) {
+	db, expect, err := gorm.NewDefaultExpecter()
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expect.First(&User{})
+	db.First(&User{})
+
+	if err := expect.AssertExpectations(); err != nil {
+		t.Error(err)
+	}
+}
+
+func TestQueryReturn(t *testing.T) {
+	db, expect, err := gorm.NewDefaultExpecter()
+	defer func() {
+		db.Close()
+	}()
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	in := User{Id: 1}
+	out := User{Id: 1, Name: "jinzhu"}
+
+	expect.First(&in).Returns(out)
+
+	db.First(&in)
+
+	if e := expect.AssertExpectations(); e != nil {
+		t.Error(e)
+	}
+
+	if in.Name != "jinzhu" {
+		t.Errorf("Expected %s, got %s", out.Name, in.Name)
+	}
+
+	if ne := reflect.DeepEqual(in, out); !ne {
+		t.Errorf("Not equal")
+	}
+}
+
+func TestFindStructDest(t *testing.T) {
+	db, expect, err := gorm.NewDefaultExpecter()
+	defer func() {
+		db.Close()
+	}()
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	in := &User{Id: 1}
+
+	expect.Find(in)
+	db.Find(&User{Id: 1})
+
+	if e := expect.AssertExpectations(); e != nil {
+		t.Error(e)
+	}
+}
+
+func TestFindSlice(t *testing.T) {
+	db, expect, err := gorm.NewDefaultExpecter()
+	defer db.Close()
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	in := []User{}
+	out := []User{User{Id: 1, Name: "jinzhu"}, User{Id: 2, Name: "itwx"}}
+
+	expect.Find(&in).Returns(&out)
+	db.Find(&in)
+
+	if e := expect.AssertExpectations(); e != nil {
+		t.Error(e)
+	}
+
+	if ne := reflect.DeepEqual(in, out); !ne {
+		t.Error("Expected equal slices")
+	}
+}
+
+func TestMockPreloadHasMany(t *testing.T) {
+	db, expect, err := gorm.NewDefaultExpecter()
+	defer db.Close()
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	in := User{Id: 1}
+	outEmails := []Email{Email{Id: 1, UserId: 1}, Email{Id: 2, UserId: 1}}
+	out := User{Id: 1, Emails: outEmails}
+
+	expect.Preload("Emails").Find(&in).Returns(out)
+	db.Preload("Emails").Find(&in)
+
+	if err := expect.AssertExpectations(); err != nil {
+		t.Error(err)
+	}
+
+	if !reflect.DeepEqual(in, out) {
+		t.Error("In and out are not equal")
+	}
+}
+
+func TestMockPreloadHasOne(t *testing.T) {
+	db, expect, err := gorm.NewDefaultExpecter()
+	defer db.Close()
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	in := User{Id: 1}
+	out := User{Id: 1, CreditCard: CreditCard{Number: "12345678"}}
+
+	expect.Preload("CreditCard").Find(&in).Returns(out)
+	db.Preload("CreditCard").Find(&in)
+
+	if err := expect.AssertExpectations(); err != nil {
+		t.Error(err)
+	}
+
+	if !reflect.DeepEqual(in, out) {
+		t.Error("In and out are not equal")
+	}
+}
+
+func TestMockPreloadMany2Many(t *testing.T) {
+	db, expect, err := gorm.NewDefaultExpecter()
+	defer db.Close()
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	in := User{Id: 1}
+	languages := []Language{Language{Name: "ZH"}}
+	out := User{Id: 1, Languages: languages}
+
+	expect.Preload("Languages").Find(&in).Returns(out)
+	db.Preload("Languages").Find(&in)
+
+	if err := expect.AssertExpectations(); err != nil {
+		t.Error(err)
+	}
+
+	if !reflect.DeepEqual(in, out) {
+		t.Error("In and out are not equal")
+	}
+}
+
+func TestMockPreloadMultiple(t *testing.T) {
+	db, expect, err := gorm.NewDefaultExpecter()
+	defer db.Close()
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	creditCard := CreditCard{Number: "12345678"}
+	languages := []Language{Language{Name: "ZH"}}
+
+	in := User{Id: 1}
+	out := User{Id: 1, Languages: languages, CreditCard: creditCard}
+
+	expect.Preload("Languages").Preload("CreditCard").Find(&in).Returns(out)
+	db.Preload("Languages").Preload("CreditCard").Find(&in)
+
+	if err := expect.AssertExpectations(); err != nil {
+		t.Error(err)
+	}
+
+	if !reflect.DeepEqual(in, out) {
+		t.Error("In and out are not equal")
+	}
+}
+
+func TestMockCreateBasic(t *testing.T) {
+	db, expect, err := gorm.NewDefaultExpecter()
+	defer db.Close()
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	user := User{Name: "jinzhu"}
+	expect.Create(&user).WillSucceed(1, 1)
+	rowsAffected := db.Create(&user).RowsAffected
+
+	if rowsAffected != 1 {
+		t.Errorf("Expected rows affected to be 1 but got %d", rowsAffected)
+	}
+
+	if user.Id != 1 {
+		t.Errorf("User id field should be 1, but got %d", user.Id)
+	}
+}
+
+func TestMockCreateError(t *testing.T) {
+	db, expect, err := gorm.NewDefaultExpecter()
+	defer db.Close()
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	mockError := errors.New("Could not insert user")
+
+	user := User{Name: "jinzhu"}
+	expect.Create(&user).WillFail(mockError)
+
+	dbError := db.Create(&user).Error
+
+	if dbError == nil || dbError != mockError {
+		t.Errorf("Expected *DB.Error to be set, but it was not")
+	}
+}
+
+func TestMockSaveBasic(t *testing.T) {
+	db, expect, err := gorm.NewDefaultExpecter()
+	defer db.Close()
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	user := User{Name: "jinzhu"}
+	expect.Save(&user).WillSucceed(1, 1)
+	expected := db.Save(&user)
+
+	if err := expect.AssertExpectations(); err != nil {
+		t.Errorf("Expectations were not met %s", err.Error())
+	}
+
+	if expected.RowsAffected != 1 || user.Id != 1 {
+		t.Errorf("Expected result was not returned")
+	}
+}
+
+func TestMockUpdateBasic(t *testing.T) {
+	db, expect, err := gorm.NewDefaultExpecter()
+	defer db.Close()
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	newName := "uhznij"
+	user := User{Name: "jinzhu"}
+
+	expect.Model(&user).Update("name", newName).WillSucceed(1, 1)
+	db.Model(&user).Update("name", newName)
+
+	if err := expect.AssertExpectations(); err != nil {
+		t.Errorf("Expectations were not met %s", err.Error())
+	}
+
+	if user.Name != newName {
+		t.Errorf("Should have name %s but got %s", newName, user.Name)
+	}
+}
+
+func TestMockUpdatesBasic(t *testing.T) {
+	db, expect, err := gorm.NewDefaultExpecter()
+	defer db.Close()
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	user := User{Name: "jinzhu", Age: 18}
+	updated := User{Name: "jinzhu", Age: 88}
+
+	expect.Model(&user).Updates(updated).WillSucceed(1, 1)
+	db.Model(&user).Updates(updated)
+
+	if err := expect.AssertExpectations(); err != nil {
+		t.Errorf("Expectations were not met %s", err.Error())
+	}
+
+	if user.Age != updated.Age {
+		t.Errorf("Should have age %d but got %d", user.Age, updated.Age)
+	}
+}
--- a/migration_test.go
+++ b/migration_test.go
@ -139,6 +139,11 @@ func (role Role) IsAdmin() bool {

 type Num int64

+func (i Num) Value() (driver.Value, error) {
+	// guaranteed ok
+	return int64(i), nil
+}
+
 func (i *Num) Scan(src interface{}) error {
 	switch s := src.(type) {
 	case []byte: