thelper detects golang test helpers without t.Helper() call. Also, it checks the consistency of test helpers and has similar checks for benchmarks and TB interface. Read further to learn more.

With this call go test prints correct lines of code for failed tests. Otherwise, printed lines will be inside helpers functions.

Compare (https://goplay.space/#I_pAJ-vWcRq):

func TestBad(t *testing.T) {
	testBad(t)
}

func testBad(t *testing.T) {
	t.Fatal("unhelpful line") // <--- output point this line
}

func TestGood(t *testing.T) {
	testGood(t) // <--- output point this line
}

func testGood(t *testing.T) {
	t.Helper()
	t.Fatal("clear output")
}

Because t.Helper() only affects asserts that are called after the t.Helper() call, so requiring it to be the first statement helps ensure all assertions in the helper function are affected.

It adds more consistency into your code. When common variables have the same name and are placed into the same position, it makes it easier to understand and read.

Note that you can also have it as the second parameter - this is primarily intended to allow compatibility with context.Context.

go install github.com/kulti/thelper/cmd/thelper@latest

golangci-lint supports thelper, so you can enable this linter and use it.

Check everything:

thelper ./...

If you run via golangci-lint look at .golangci.example.yml for an example of the configuration.

Otherwise you can run thelper with --checks command line argument. E.g. the following command checks that *testing.T is the first param and *testing.B is named b:

thelper --checks=t_first,b_name ./...

• t_begin - t.Helper() should begin helper function.
• t_name - *testing.T should be named t.
• t_first - *testing.T should be the first param of helper function.

The same for fuzzing, benchmarks and TB interface:

• f_begin - f.Helper() should begin helper function.
• f_name - *testing.F should be named f.
• f_first - *testing.F should be the first param of helper function.
• b_begin - b.Helper() should begin helper function.
• b_name - *testing.B should be named b.
• b_first - *testing.B should be the first param of helper function.
• tb_begin - tb.Helper() should begin helper function.
• tb_name - *testing.TB should be named tb.
• tb_first - *testing.TB should be the first param of helper function.

• t_name allows using _ name.
• t_begin allows subtests and fuzz tests not begin from t.Helper().
• t_first allows to be the second after context.Context param.

func TestSmth(t *testing.T) {
	checkSmth(t)
}

// Bad
func checkSmth(t *testing.T) {
	t.Fatal("check failed")
}

// Good
func checkSmth(t *testing.T) {
	t.Helper()
	t.Fatal("check failed")
}

// Bad
func checkSmth(tt *testing.T) {
    // ...
}

// Good
func checkSmth(t *testing.T) {
    // ...
}

// Bad
func checkSmth(doneCh <-chan struct{}, t *testing.T) {
    // ...
}

// Good
func checkSmth(t *testing.T, doneCh <-chan struct{}) {
    // ...
}