Verification

We will use the following interface for the examples:

Go

package main

import (
    . "github.com/ovechkin-dm/mockio/mock"
    "testing"
)

type Greeter interface {
    Greet(name any) string
}

func TestSimple(t *testing.T) {
    SetUp(t)
    greeter := Mock[Greeter]()
    When(greeter.Greet("Jane")).ThenReturn("hello world")
    greeter.Greet("John")

}

Verify

To verify that a method was called, use the Verify function. If the method was called, the test will pass. If the method was not called, the test will fail.

This test will succeed:

Go

func TestSimple(t *testing.T) {
    SetUp(t)
    greeter := Mock[Greeter]()
    When(greeter.Greet("Jane")).ThenReturn("hello world")
    greeter.Greet("John")
    Verify(greeter, Once()).Greet("John")
}

This test will fail:

Go

func TestSimple(t *testing.T) {
    SetUp(t)
    greeter := Mock[Greeter]()
    When(greeter.Greet("Jane")).ThenReturn("hello world")
    greeter.Greet("John")
    Verify(greeter, Once()).Greet("Jane")
}

AtLeastOnce

Verify that a method was called at least once:

Go

func TestSimple(t *testing.T) {
    SetUp(t)
    greeter := Mock[Greeter]()
    When(greeter.Greet("Jane")).ThenReturn("hello world")
    greeter.Greet("John")
    Verify(greeter, AtLeastOnce()).Greet("John")
}

Once

Verify that a method was called exactly once:

Go

func TestSimple(t *testing.T) {
    SetUp(t)
    greeter := Mock[Greeter]()
    When(greeter.Greet("Jane")).ThenReturn("hello world")
    greeter.Greet("John")
    Verify(greeter, Once()).Greet("John")
}

Times

Verify that a method was called a specific number of times:

Go

func TestSimple(t *testing.T) {
    SetUp(t)
    greeter := Mock[Greeter]()
    When(greeter.Greet("Jane")).ThenReturn("hello world")
    greeter.Greet("John")
    greeter.Greet("John")
    Verify(greeter, Times(2)).Greet("John")
}

VerifyNoMoreInteractions

To verify that no other methods were called on the mock object, use the VerifyNoMoreInteractions function. It will fail the test if there are any unverified calls.

This test will succeed:

Go

func TestSimple(t *testing.T) {
    SetUp(t)
    greeter := Mock[Greeter]()
    When(greeter.Greet("Jane")).ThenReturn("hello world")
    greeter.Greet("John")
    Verify(greeter, Once()).Greet("John")
    VerifyNoMoreInteractions(greeter)
}

This test will fail:

Go

func TestSimple(t *testing.T) {
    SetUp(t)
    greeter := Mock[Greeter]()
    When(greeter.Greet("John")).ThenReturn("hello world")
    greeter.Greet("John")
    VerifyNoMoreInteractions(greeter)
}

Verify after ThenReturn

Since it is common to actually verify that a stub was used correctly, you can use the Verify function after the ThenReturn function:

Go

func TestSimple(t *testing.T) {
    SetUp(t)
    greeter := Mock[Greeter]()
    When(greeter.Greet("John")).ThenReturn("hello world").Verify(Once())
    greeter.Greet("John")
    VerifyNoMoreInteractions(greeter)
}