Gomock Matcher

Matching library for use with golang/gomock

Usage

All matchers in this package implements the Matcher interface and can thusly be used with mocks from golang/gomock.

Example usage of Record matcher, but all matchers work in a similar way:

import "github.com/Storytel/gomock-matchers"

func TestSomething(t *testing.T) {
  // Set up a new matcher
  matcher := matchers.Record(gomock.Eq(12))

  // Expect `MyFunc` to be called on `mock` with argument equal to 12
  mock.EXPECT().MyFunc(matcher).Return(nil)

  // Run the test this which will expect the EXPECT()
  DUT()

  // For the RecordMatcher, you can get the argument. Other matchers have other characteristics.
  if 12 != matcher.Get().(int) {
    t.Fail()
  }
}

Matchers

RegexpMatcher - Matcher which accepts a string to be interpreted as a Go Regexp.

Regexpmatcher returns a matcher which will match if the supplied string, interpreted as a regexp, matches the input string.

This is useful when you don't know exactly what the string might be in a run. Maybe it's a timestamp or something else outside of your control.

func TestRegexpMatcher(t *testing.T) {
  m := matchers.Regexp("^[^@]+@.+$")
  m.Matches("donald_duck@duckburg.di") // true
  m.Matches("daisy") // false
}

RecordMatcher - Proxy matcher which captures the argument for further inspection.

Wraps another matcher and records the value of the argument it's called with.

This can be used if you need to do further investigations. For instance when the argument is a function, and you want to test that function.

type MyFunc func() int

func TestRecord(t *testing.T) {
	assert := assert.New(t)
	m := matchers.Record(gomock.Any())

	m.Matches(MyFunc(func () int { return 12 }))

	f, ok := m.Get().(MyFunc)
	assert.True(ok)
	assert.Equal(12, f())
}

SameMatcher - Matcher which checks if values are the same

This differs from gomock.Eq in that it does a comparison check with == and not a reflect.DeepEqual. This means that two pointers are only same if they point to the same memory address

func TestSame(t *testing.T) {
  assert := assert.New(t)

  myString := "something"
  otherString := "something"

  m := matchers.Same(&myString)
  assert.True(m.Matches(&myString))
  assert.False(m.Matches(&otherString)) // Not the same pointer

  m2 := matchers.Same(myString)
  assert.True(m2.Matches(myString))
  assert.True(m2.Matches(otherString)) // Not pointers, values are the same
}

AsyncBlockMatcher - Matcher which provides channel signaling when `Matches` is called

AsyncBlock returns a matcher holding a channel which will be signaled when the Matches function is called. AsyncBlock will wrap any other matcher to do the actual matching.

This is useful if the code you're testing is spawning a go function which will invoke your mock at some time in the future. The channel gives you an easy way to wait for that invokation (using <- matcher.Channel()) and then do assertions.

func TestAsyncBlockMatcher(t *testing.T) {
	assert := assert.New(t)
	m := matchers.AsyncBlock(gomock.Eq("12"))

	didMatch := false
	go func() {
		didMatch = m.Matches("12")
	}()

  // This blocks until `Matches` is actually called
	<-m.Channel()
	assert.True(didMatch)
}