Mocking in golang? How to make unit-test more simple?

GO111MODULE=on go get github.com/golang/mock/mockgen@v1.4.4

package structure

type Stacker interface {
	Append(interface{}) []interface{}
}

type Queuer interface {
	Enque(interface{}) []interface{}
}

mockgen -source=structure.go

// Code generated by MockGen. DO NOT EDIT.
// Source: structure.go

// Package mock_structure is a generated GoMock package.
package mock_structure

import (
	gomock "github.com/golang/mock/gomock"
	reflect "reflect"
)

// MockStacker is a mock of Stacker interface
type MockStacker struct {
	ctrl     *gomock.Controller
	recorder *MockStackerMockRecorder
}

// MockStackerMockRecorder is the mock recorder for MockStacker
type MockStackerMockRecorder struct {
	mock *MockStacker
}

// NewMockStacker creates a new mock instance
func NewMockStacker(ctrl *gomock.Controller) *MockStacker {
	mock := &MockStacker{ctrl: ctrl}
	mock.recorder = &MockStackerMockRecorder{mock}
	return mock
}

// EXPECT returns an object that allows the caller to indicate expected use
func (m *MockStacker) EXPECT() *MockStackerMockRecorder {
	return m.recorder
}

// Append mocks base method
func (m *MockStacker) Append(arg0 interface{}) []interface{} {
	m.ctrl.T.Helper()
	ret := m.ctrl.Call(m, "Append", arg0)
	ret0, _ := ret[0].([]interface{})
	return ret0
}

// Append indicates an expected call of Append
func (mr *MockStackerMockRecorder) Append(arg0 interface{}) *gomock.Call {
	mr.mock.ctrl.T.Helper()
	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Append", reflect.TypeOf((*MockStacker)(nil).Append), arg0)
}

// MockQueuer is a mock of Queuer interface
type MockQueuer struct {
	ctrl     *gomock.Controller
	recorder *MockQueuerMockRecorder
}

// MockQueuerMockRecorder is the mock recorder for MockQueuer
type MockQueuerMockRecorder struct {
	mock *MockQueuer
}

// NewMockQueuer creates a new mock instance
func NewMockQueuer(ctrl *gomock.Controller) *MockQueuer {
	mock := &MockQueuer{ctrl: ctrl}
	mock.recorder = &MockQueuerMockRecorder{mock}
	return mock
}

// EXPECT returns an object that allows the caller to indicate expected use
func (m *MockQueuer) EXPECT() *MockQueuerMockRecorder {
	return m.recorder
}

// Enque mocks base method
func (m *MockQueuer) Enque(arg0 interface{}) []interface{} {
	m.ctrl.T.Helper()
	ret := m.ctrl.Call(m, "Enque", arg0)
	ret0, _ := ret[0].([]interface{})
	return ret0
}

// Enque indicates an expected call of Enque
func (mr *MockQueuerMockRecorder) Enque(arg0 interface{}) *gomock.Call {
	mr.mock.ctrl.T.Helper()
	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Enque", reflect.TypeOf((*MockQueuer)(nil).Enque), arg0)
}

mockgen . Queuer, Stacker # is "." is referenced to the current path's package, this is good for using with go generate
# Or mockgen github.com/kurojs/gomock Queuer,Stacker

-source: A file containing interfaces to be mocked. Cannot use with Reflect mode.

-destination: A file to which to write the resulting source code. If you don't set this, the code is printed to standard output.
High recommented given full package path here. Example: -destination=github.com/kurojs/gomock/mock_something.go

-package: The package to use for the resulting mock class source code. If you don't set this, the package name is mock_ concatenated with the package of the input file.

-imports: A list of explicit imports that should be used in the resulting source code, specified as a comma-separated list of elements of the form foo=bar/baz, where bar/baz is the package being imported and foo is the identifier to use for the package in the generated source code.

-aux_files: A list of additional files that should be consulted to resolve e.g. embedded interfaces defined in a different file. This is specified as a comma-separated list of elements of the form foo=bar/baz.go, where bar/baz.go is the source file and foo is the package name of that file used by the -source file.

-build_flags: (reflect mode only) Flags passed verbatim to go build.

-mock_names: A list of custom names for generated mocks. This is specified as a comma-separated list of elements of the form Repository=MockSensorRepository,Endpoint=MockSensorEndpoint, where Repository is the interface name and MockSensorRepository is the desired mock name (mock factory method and mock recorder will be named after the mock). If one of the interfaces has no custom name specified, then default naming convention will be used.

-self_package: The full package import path for the generated code. The purpose of this flag is to prevent import cycles in the generated code by trying to include its own package. This can happen if the mock's package is set to one of its inputs (usually the main one) and the output is stdio so mockgen cannot detect the final output package. Setting this flag will then tell mockgen which import to exclude.

-copyright_file: Copyright file used to add copyright header to the resulting source code.

mock := mock.NewMockStacker(ctrl)
// Assert mock are called 3 times
for i := 1; i <= 3; i++ {
	mock.EXPECT().Append(gomock.Eq(i))
}
// And return 3
mock.EXPECT().Pop().Return(3)

mock := mock.NewMockStacker(ctrl)
// No assertion, just return the expected data
mock.EXPECT().Append(gomock.Any()).AnyTimes()
mock.EXPECT().Pop().DoAndReturn(func() interface{} {
	return 3
})