oglemock is a mocking framework for the Go programming language with the following features:

• An extensive and extensible set of matchers for expressing call expectations (provided by the oglematchers package).

• Clean, readable output that tells you exactly what you need to know.

• Style and semantics similar to Google Mock and Google JS Test.

• Seamless integration with the ogletest unit testing framework.

It can be integrated into any testing framework (including Go's testing package), but out of the box support is built in to ogletest and that is the easiest place to use it.

Installation

First, make sure you have installed Go 1.0.2 or newer. See here for instructions.

Use the following command to install oglemock and its dependencies, and to keep them up to date:

go get -u github.com/jacobsa/oglemock
go get -u github.com/jacobsa/oglemock/createmock

Those commands will install the oglemock package itself, along with the createmock tool that is used to auto-generate mock types.

Generating and using mock types

Automatically generating a mock implementation of an interface is easy. If you want to mock interfaces Bar and Baz from package foo, simply run the following:

createmock foo Bar Baz

That will print source code that can be saved to a file and used in your tests. For example, to create a mock_io package containing mock implementations of io.Reader and io.Writer:

mkdir mock_io
createmock io Reader Writer > mock_io/mock_io.go

The new package will be named mock_io, and contain types called MockReader and MockWriter, which implement io.Reader and io.Writer respectively.

For each generated mock type, there is a corresponding function for creating an instance of that type given a Controller object (see below). For example, to create a mock reader:

someController := [...]  // See next section.
someReader := mock_io.NewMockReader(someController, "Mock file reader")

The snippet above creates a mock io.Reader that reports failures to someController. The reader can subsequently have expectations set up and be passed to your code under test that uses an io.Reader.

Getting ahold of a controller

oglemock.Controller is used to create mock objects, and to set up and verify expectations for them. You can create one by calling NewController with an ErrorReporter, which is the basic type used to interface between oglemock and the testing framework within which it is being used.

If you are using ogletest you don't need to worry about any of this, since the TestInfo struct provided to your test's SetUp function already contains a working Controller that you can use to create mock object, and you can use the built-in ExpectCall function for setting expectations. (See the ogletest documentation for more info.) Otherwise, you will need to implement the simple ErrorReporter interface for your test environment.

Documentation

For thorough documentation, including information on how to set up expectations, see here.