[PATCH] Omit sync package while mocking empty interface

when just an empty interface is has beeing mocked, the import of the sync package caused an error. In production it isn't important, because mocking empty interfaces might be stupid, but while writing tests it might happen, that you create an interface, which is beeing filled later on.

pkg/moq/moq.go

@@ -69,6 +69,7 @@ func (m *Mocker) Mock(w io.Writer, name ...string) error {
 		PackageName: m.pkgName,
 		Imports:     moqImports,
 	}
+	mocksMethods := false
 	for _, pkg := range m.pkgs {
 		i := 0
 		files := make([]*ast.File, len(pkg.Files))
@@ -94,6 +95,7 @@ func (m *Mocker) Mock(w io.Writer, name ...string) error {
 				InterfaceName: n,
 			}
 			for i := 0; i < iiface.NumMethods(); i++ {
+				mocksMethods = true
 				meth := iiface.Method(i)
 				sig := meth.Type().(*types.Signature)
 				method := &method{
@@ -106,6 +108,9 @@ func (m *Mocker) Mock(w io.Writer, name ...string) error {
 			doc.Objects = append(doc.Objects, obj)
 		}
 	}
+	if mocksMethods {
+		doc.Imports = append(doc.Imports, "sync")
+	}
 	for pkgToImport := range m.imports {
 		doc.Imports = append(doc.Imports, pkgToImport)
 	}

pkg/moq/moq_test.go

@@ -214,3 +214,19 @@ func TestDotImports(t *testing.T) {
 		t.Error("contains invalid dot import")
 	}
 }
+
+func TestEmptyInterface(t *testing.T) {
+	m, err := New("testpackages/emptyinterface", "")
+	if err != nil {
+		t.Fatalf("moq.New: %s", err)
+	}
+	var buf bytes.Buffer
+	err = m.Mock(&buf, "Empty")
+	if err != nil {
+		t.Errorf("mock error: %s", err)
+	}
+	s := buf.String()
+	if strings.Contains(s, `"sync"`) {
+		t.Error("contains sync import, although this package isn't used")
+	}
+}

pkg/moq/template.go

@@ -1,7 +1,7 @@
 package moq
 
 // moqImports are the imports all moq files get.
-var moqImports = []string{"sync"}
+var moqImports = []string{}
 
 // moqTemplate is the template for mocked code.
 var moqTemplate = `// Code generated by moq; DO NOT EDIT
@@ -35,7 +35,7 @@ var (
 //
 //         // TODO: use mocked{{.InterfaceName}} in code that requires {{.InterfaceName}}
 //         //       and then make assertions.
-// 
+//
 //     }
 type {{.InterfaceName}}Mock struct {
 {{- range .Methods }}
@@ -43,7 +43,7 @@ type {{.InterfaceName}}Mock struct {
 	{{.Name}}Func func({{ .Arglist }}) {{.ReturnArglist}}
 {{ end }}
 	// calls tracks calls to the methods.
-	calls struct {		
+	calls struct {
 {{- range .Methods }}
 		// {{ .Name }} holds details about calls to the {{.Name}} method.
 		{{ .Name }} []struct {