Support nil arguments to Argument Matchers

mock/mock.go

@@ -1,6 +1,7 @@
 package mock
 
 import (
+	"errors"
 	"fmt"
 	"reflect"
 	"regexp"
@@ -518,9 +519,25 @@ type argumentMatcher struct {
 
 func (f argumentMatcher) Matches(argument interface{}) bool {
 	expectType := f.fn.Type().In(0)
+	expectTypeNilSupported := false
+	switch expectType.Kind() {
+	case reflect.Interface, reflect.Chan, reflect.Func, reflect.Map, reflect.Slice, reflect.Ptr:
+		expectTypeNilSupported = true
+	}
 
-	if reflect.TypeOf(argument).AssignableTo(expectType) {
-		result := f.fn.Call([]reflect.Value{reflect.ValueOf(argument)})
+	argType := reflect.TypeOf(argument)
+	var arg reflect.Value
+	if argType == nil {
+		arg = reflect.New(expectType).Elem()
+	} else {
+		arg = reflect.ValueOf(argument)
+	}
+
+	if argType == nil && !expectTypeNilSupported {
+		panic(errors.New("attempting to call matcher with nil for non-nil expected type"))
+	}
+	if argType == nil || argType.AssignableTo(expectType) {
+		result := f.fn.Call([]reflect.Value{arg})
 		return result[0].Bool()
 	}
 	return false

mock/mock_test.go

@@ -42,6 +42,26 @@ func (i *TestExampleImplementation) TheExampleMethod3(et *ExampleType) error {
 	return args.Error(0)
 }
 
+func (i *TestExampleImplementation) TheExampleMethod4(v ExampleInterface) error {
+	args := i.Called(v)
+	return args.Error(0)
+}
+
+func (i *TestExampleImplementation) TheExampleMethod5(ch chan struct{}) error {
+	args := i.Called(ch)
+	return args.Error(0)
+}
+
+func (i *TestExampleImplementation) TheExampleMethod6(m map[string]bool) error {
+	args := i.Called(m)
+	return args.Error(0)
+}
+
+func (i *TestExampleImplementation) TheExampleMethod7(slice []bool) error {
+	args := i.Called(slice)
+	return args.Error(0)
+}
+
 func (i *TestExampleImplementation) TheExampleMethodFunc(fn func(string) error) error {
 	args := i.Called(fn)
 	return args.Error(0)
@@ -181,15 +201,20 @@ func Test_Mock_On_WithPtrArgMatcher(t *testing.T) {
 	var mockedService TestExampleImplementation
 
 	mockedService.On("TheExampleMethod3",
-		MatchedBy(func(a *ExampleType) bool { return a.ran == true }),
+		MatchedBy(func(a *ExampleType) bool { return a != nil && a.ran == true }),
 	).Return(nil)
 
 	mockedService.On("TheExampleMethod3",
-		MatchedBy(func(a *ExampleType) bool { return a.ran == false }),
+		MatchedBy(func(a *ExampleType) bool { return a != nil && a.ran == false }),
 	).Return(errors.New("error"))
 
+	mockedService.On("TheExampleMethod3",
+		MatchedBy(func(a *ExampleType) bool { return a == nil }),
+	).Return(errors.New("error2"))
+
 	assert.Equal(t, mockedService.TheExampleMethod3(&ExampleType{true}), nil)
 	assert.EqualError(t, mockedService.TheExampleMethod3(&ExampleType{false}), "error")
+	assert.EqualError(t, mockedService.TheExampleMethod3(nil), "error2")
 }
 
 func Test_Mock_On_WithFuncArgMatcher(t *testing.T) {
@@ -198,17 +223,62 @@ func Test_Mock_On_WithFuncArgMatcher(t *testing.T) {
 	fixture1, fixture2 := errors.New("fixture1"), errors.New("fixture2")
 
 	mockedService.On("TheExampleMethodFunc",
-		MatchedBy(func(a func(string) error) bool { return a("string") == fixture1 }),
+		MatchedBy(func(a func(string) error) bool { return a != nil && a("string") == fixture1 }),
 	).Return(errors.New("fixture1"))
 
 	mockedService.On("TheExampleMethodFunc",
-		MatchedBy(func(a func(string) error) bool { return a("string") == fixture2 }),
+		MatchedBy(func(a func(string) error) bool { return a != nil && a("string") == fixture2 }),
 	).Return(errors.New("fixture2"))
 
+	mockedService.On("TheExampleMethodFunc",
+		MatchedBy(func(a func(string) error) bool { return a == nil }),
+	).Return(errors.New("fixture3"))
+
 	assert.EqualError(t, mockedService.TheExampleMethodFunc(
 		func(string) error { return fixture1 }), "fixture1")
 	assert.EqualError(t, mockedService.TheExampleMethodFunc(
 		func(string) error { return fixture2 }), "fixture2")
+	assert.EqualError(t, mockedService.TheExampleMethodFunc(nil), "fixture3")
+}
+
+func Test_Mock_On_WithInterfaceArgMatcher(t *testing.T) {
+	var mockedService TestExampleImplementation
+
+	mockedService.On("TheExampleMethod4",
+		MatchedBy(func(a ExampleInterface) bool { return a == nil }),
+	).Return(errors.New("fixture1"))
+
+	assert.EqualError(t, mockedService.TheExampleMethod4(nil), "fixture1")
+}
+
+func Test_Mock_On_WithChannelArgMatcher(t *testing.T) {
+	var mockedService TestExampleImplementation
+
+	mockedService.On("TheExampleMethod5",
+		MatchedBy(func(ch chan struct{}) bool { return ch == nil }),
+	).Return(errors.New("fixture1"))
+
+	assert.EqualError(t, mockedService.TheExampleMethod5(nil), "fixture1")
+}
+
+func Test_Mock_On_WithMapArgMatcher(t *testing.T) {
+	var mockedService TestExampleImplementation
+
+	mockedService.On("TheExampleMethod6",
+		MatchedBy(func(m map[string]bool) bool { return m == nil }),
+	).Return(errors.New("fixture1"))
+
+	assert.EqualError(t, mockedService.TheExampleMethod6(nil), "fixture1")
+}
+
+func Test_Mock_On_WithSliceArgMatcher(t *testing.T) {
+	var mockedService TestExampleImplementation
+
+	mockedService.On("TheExampleMethod7",
+		MatchedBy(func(slice []bool) bool { return slice == nil }),
+	).Return(errors.New("fixture1"))
+
+	assert.EqualError(t, mockedService.TheExampleMethod7(nil), "fixture1")
 }
 
 func Test_Mock_On_WithVariadicFunc(t *testing.T) {