mock

gomock

GoMock is a mocking framework for the Go programming language. It integrates well with Go's built-in testing package, but can be used in other contexts too. This is a fork that allows the gomock library to print its output as a diff. This is especially useful when the mock receives a map or a slice and errors. Instead of showing a gigantic blob, wrapping in the terminal several times, you get just the parts of the argument that are different.

Installation

Install and gomock/mockgen as normal, then:

mkdir vendor
git clone git@github.com:fishybell/mock vendor/mock
echo "replace github.com/fishybell/mock => ./vendor/mock" >> go.mod

This is necessary as the mock package uses types rather than interfaces.

If you are using a Matcher, extending the Matcher interface to be a DiffableMatcher interface is required for fancier output:

// A DiffableMatcher is a representation of a class of values.
// It is used to represent the valid or expected arguments to a mocked method.
// The only difference is the Value() function to allow for full matching
type DiffableMatcher interface {
	// Matches returns whether x is a match.
	Matches(x interface{}) bool

	// String describes what the matcher matches.
	String() string

	// Value returns the original value, for use in Diff output
	Value() interface{}
}

This is exactly the same as the Matcher interface, with the addition of the Value() function. You can continue to use the Matcher interface if you wish.