Comparison of golang mocking libraries

golang-mocks.md

Comparison of golang mocking libraries

Updated 2024-09-01

	gomock	testify + mockery	mockio	minimock	moq
Library
GitHub stars		+
Latest release date		+
Maintained	✅	✅	✅	✅	✅
Notes	1		2
Mock creation
Code generation 3	✅	✅	✖️	✅	✅
Works without code generation 4	❌	✅	✅	❌	❌
Use t.Cleanup() 5	✅	✅	✅	✅	❌
Support generics	✅	✅	✅	✅	✅
DSL
Execute custom func 6	✅	✅	✅	✅	✅
Calls order 7	✅	✅	❌	❌	❌
Wait for time.Duration 8	❌	✅	❌	❌	❌
Wait for message from chan 9	❌	✅	❌	❌	❌
Panic 10	❌	✅	❌	❌	❌
Assert expectations with timeout	❌	❌	❌	✅	❌
Return zero values by default 11	✅	❌	✅	❌	❌
Capturer 12	❌	✅	✅	✅	✅
Calls count
Exact calls count 13	✅	✅	✅	✅	❌
Min/max calls count 14	✅	❌	❌	❌	❌
Called at least once	✅	❌	✅	❌	❌
Don't check calls count	✅	✅	✅	✅	❌
Expect once by default 15	✅	❌	❌	❌	❌
Matchers
Any value	✅	✅	✅	✅	❌
Equal to (reflect)	✅	✅	✅	✅	❌
Not equal to	✅	❌	✅	❌	❌
Exact (==)	❌	❌	✅	❌	❌
One of values	✅	❌	✅	❌	❌
Regex	✅	❌	✅	❌	❌
Substring	❌	❌	✅	❌	❌
Is nil	✅	❌	✅	❌	❌
Not nil	✅	❌	✅	❌	❌
Type is	✅	✅	✅	❌	❌
Length is	✅	❌	✔️ 16	❌	❌
Slice elements in any order	✅	❌	✅	❌	❌
Slice contains	❌	❌	✅	❌	❌
Map contains keys	❌	❌	✅	❌	❌
Functional options	❌	✅	❌	❌	❌
Logical operations on matchers	✅	❌	❌	❌	❌
Custom matcher	✅	✅	✅	✅	❌

Examples

gomock

func TestUberGomock(t *testing.T) {
	ctrl := gomock.NewController(t)
	m := NewMockMyInterface(ctrl)
	gomock.InOrder(
		m.EXPECT().Method(gomock.Any(), "abc").Return(123, nil),
		m.EXPECT().AnotherMethod(gomock.Any(), gomock.Len(3)),
	)
	...
}

testify/mock + mockery

func TestTestifyMock(t *testing.T) {
	m := mocks.NewMyInterface(t)
	m.EXPECT().Method(mock.Anything, "abc").After(5*time.Second).Return(123, nil).Once()
	m.EXPECT().AnotherMethod(mock.Anything, "abc").Return(0, nil).Once()
	...
}

mockio

func TestMockio(t *testing.T) {
	mock.SetUp(t, mockopts.StrictVerify())
	m := mock.Mock[MyInterface]()
	mock.WhenDouble(m.Method(mock.AnyContext(), mock.Equal("abc"))).ThenReturn(123, nil).Verify(mock.Once())
	mock.WhenDouble(m.AnotherMethod(mock.AnyContext(), mock.Regex("ab?c"))).Verify(mock.Once())
	captor := mock.Captor[string]()
	mock.WhenDouble(m.Method(mock.AnyContext(), captor.Capture()))
	...
	assert.Equal(t, "abc", captor.Last())
}

minimock

func TestMinimock(t *testing.T) {
	ctrl := minimock.NewController(t)
	m := NewMyInterfaceMock(ctrl)
	m.MethodMock.When(minimock.AnyContext, "abc").Then(123, nil)
	m.AnotherMethodMock.When(minimock.AnyContext, "abc").Then(0, nil)
	...
}

moq

func TestMoq(t *testing.T) {
	m := MyInterfaceMock{
		MethodFunc: func(ctx context.Context, s string) (int, error) {
			assert.Equal(t, "abc", s)
			return 123, nil
		},
		AnotherMethodFunc: func(ctx context.Context, s string) (int, error) {
			assert.Len(t, s, 1)
			return 0, nil
		},
	}
	t.Cleanup(func() {
		assert.Len(t, m.MethodCalls(), 1)
		assert.Len(t, m.AnotherMethodCalls(), 1)
	})
	...
}

Footnotes

1. Google stopped maintaining the original gomock with 9K stars, Uber forked it and continue development ↩

2. mockio supports only amd64 and arm64 processors and it heavily depends on compiler internals and unsafe package ↩

3. CLI tool to auto generate mocks from interfaces ↩

4. Create mocks in runtime, without code generation ↩

5. Mock constructor uses t.Cleanup() to assert expectations after test by default ↩

6. Use arbitrary function to execute, allowing to implement any feature in the table ↩

7. Define expected order of calls ↩

8. Block execution of method using time.Sleep() ↩

9. Block execution of method using <- channel ↩

10. Panic instead of method execution ↩

11. Not defining return values leads to returning zero values ↩

12. Ability to capture actual call arguments to validate them later (not in mock) ↩

13. Define expected exact number of calls in test ↩

14. Define expected min/max number of calls in test ↩

15. Not defining number of calls leads to expectation that method to be called once ↩

16. There are only length matchers for slices and maps, not for strings ↩

@m1khal3v @Zurvarian I've added mockio to the table

Hi, thanks for your great comparison.

Just a small correction: minimock has a "Capturer" capability. All call parameters are stored in a mock and may be accessed later via Calls() function.

@mbalabin good catch, thanks! Actually, all libs but gomock allow introspecting calls afterward. IMO, mockio provides the best API for that, but I've updated the table accordingly.

@m1khal3v @Zurvarian I've added mockio to the table

Thank you for adding mockio to your table.
The feature set for it is very accurate.