Bintest

⚠️ This is an open-sourced tool we use internally. You're welcome to use it, but we are unable to provide support.

A set of tools for generating fake binaries that can be used for testing. A binary is compiled and then can be orchestrated from your test suite and later checked for assertions.

Mocks can communicate and respond in real-time with the tests that are calling them, which allows for testing complicated dependencies. See https://github.com/buildkite/agent/tree/master/bootstrap/integration for how we use it to test buildkite-agent's bootstrap process.

Mocks

Mocks are your typical mock object, but as an executable that your code can shell out to and then later test assertions on.

agent, err := bintest.NewMock("buildkite-agent")
if err != nil {
  t.Fatal(err)
}

agent.
  Expect("meta-data", "exists", "buildkite:git:commit").
  AndExitWith(1)
agent.
  Expect("meta-data", "set", mock.MatchAny()).
  AndExitWith(0)
agent.
  Expect("meta-data", "set", "buildkite:git:branch", mock.MatchAny()).
  AndExitWith(0)

agent.CheckAndClose(t)

Proxies

Proxies are what power Mocks.

// Compile a proxy for the git command that echos some debug
proxy, err := bintest.CompileProxy("git")
if err != nil {
  log.Fatal(err)
}

// call the proxy like a normal binary
go fmt.Println(exec.Command("git", "test", "arguments").CombinedOutput())

// handle invocations of the proxy binary
for call := range proxy.Ch {
  fmt.Fprintln(call.Stdout, "Llama party! 🎉")
  call.Exit(0)
}

// Llama party! 🎉

Credit

Inspired by bats-mock and go-binmock.