README
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Test Setup and Teardown
It is somewhat common (especially coming from different languages) to have test frameworks that support test case setups and teardowns. Some common examples that would be useful to have setup and teardown
- loading a file and cleaning that up afterwards
- database setup and teardown
I will share two different ways to achieve these using some examples.
Creating setup and teardown functions
One approach is to create your own setup and teardown functions that you can add to each test. A convenient way is to use defer to invoke your teardown functions. example2.1_test.go illustrates this.
Using TestMain in Go 1.4
In Go 1.4, TestMain was introduced. As mentioned in the release notes
The testing package has a new facility to provide more control over running a set of tests. If the test code contains a function
func TestMain(m *testing.M)that function will be called instead of running the tests directly. The M struct contains methods to access and run the tests.
example2.2_test.go illustrates this.
Besides test setup and teardown, this can also be a useful way to test subprocesses.
Another use-case is to ensure code runs in the main goroutine that is locked to the main OS thread, where the tests can be run in another goroutine. For example, graphics related code / libraries are very particular about this. Consider
func init() {
// LockOSThread wires the calling goroutine to its current operating system thread
runtime.LockOSThread()
}
func TestMain(m *testing.Main) {
go func() {
os.Exit(m.Run())
}()
runCodeInMainThread()
}
The example above ensures runCodeInMainThread() runs in the main thread, and the package tests will assumingly be testing APIs from that function.
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