Golang testing — gotest.tools skip

Sat, 9 September, 2018 (400 Words)

Let’s continue the gotest.tools serie, this time with the skip package. This is a really simple one so this should be quick.

skip provides functions for skipping a test and printing the source code of the condition used to skip the test.

The package consists of only one function : If. The idea comes mainly from docker/docker integration test suite, where we wanted to skip some test (or test suites) given different context. By context I mean things like the system we are running on (Windows, Linux, …) or the capabilities of the running kernel or node (is apparmor available or not on the current machine).

This If method takes a testing.T pointer and either a boolean, a function that returns a boolean, or an expression.

// boolean
//   --- SKIP: TestName (0.00s)
//           skip.go:19: MissingFeature
var MissingFeature bool
skip.If(t, MissingFeature)

// function
//   --- SKIP: TestName (0.00s)
//           skip.go:19: !IsExperimentalDaemon(dockerClient): daemon is not experimental
skip.If(t, IsExperimentalDaemon(dockerClient), "daemon is not experimental")

// expression
//   --- SKIP: TestName (0.00s)
//           skip.go:19: apiVersion < version("v1.24")
skip.If(t, apiVersion < version("v1.24"))

There is few elements to note though :

  • This package (as other parts of the gotest.tools packages), will try to look at source files to display the expression used (same goes for assert). This is usually not a problem because you run tests where the source code is. However, in the cases you generate a test binary to be executed later (à-la kubernetes or other projects), this can display a weird error message if the sources are not available… You shouldn’t be worried too much about it, but it’s better if you know :)
  • The main reason to use skip.If is mainly for new contributors to get in quickly, reducing potential friction of them running the tests on their environment. The more the tests are written in a way they explicitely declare their requirements (and skipped if the environment does not meet those), the easier it makes contributors run your tests. But, this also means, you should try to measure the skipped tests on your continuous integration system to make sure you run all of them eventually… otherwise it’s dead code. But more on that in later posts 😉.

That’s all for today folks, told you that was going to be quick.