maratori/golang-mocks.md

## golang-mocks.md

      
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              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


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


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


CLI tool to auto generate mocks from interfaces ↩


Create mocks in runtime, without code generation ↩


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


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


Define expected order of calls ↩


Block execution of method using time.Sleep() ↩


Block execution of method using <- channel ↩


Panic instead of method execution ↩


Not defining return values leads to returning zero values ↩


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


Define expected exact number of calls in test ↩


Define expected min/max number of calls in test ↩


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


There are only length matchers for slices and maps, not for strings ↩
	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	✅	✅	✅	✅	❌