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
Once you have installed Go, run these commands
to install the gomock package and the mockgen tool:
go get github.com/golang/mock/gomock
go get github.com/golang/mock/mockgen
After installing, you can use go doc to get documentation:
go doc github.com/golang/mock/gomock
Alternatively, there is an online reference for the package hosted on GoPkgDoc
mockgen has two modes of operation: source and reflect.
Source mode generates mock interfaces from a source file.
It is enabled by using the -source flag. Other flags that
may be useful in this mode are -imports and -aux_files.
mockgen -source=foo.go [other options]
Reflect mode generates mock interfaces by building a program
that uses reflection to understand interfaces. It is enabled
by passing two non-flag arguments: an import path, and a
comma-separated list of symbols.
mockgen database/sql/driver Conn,Driver
The mockgen command is used to generate source code for a mock
class given a Go source file containing interfaces to be mocked.
It supports the following flags:
-source: A file containing interfaces to be mocked.
-destination: A file to which to write the resulting source code. If you
don’t set this, the code is printed to standard output.
-package: The package name 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.
-self_package: The package this mock will be part of. Setting this
ensures that the package is not included in the imports.
-source_package: The package of the types in the source file. Setting
this ensures that types referenced by the interfaces in the source file
will be properly qualified.
For an example of the use of mockgen, see the sample/ directory. In simple
cases, you will need only the -source flag.
TODO: Brief overview of how to create mock objects and set up expectations, and