func TestStringsIndex(t *testing.T) {
// Notice:
// - No need of test struct definitions
// - The args to f can be thought of as following:
// - First few args are given conditions
// - Last arg is always the want condition
f := func(s, substr string, nExpected int) {
t.Helper()
n := strings.Index(s, substr)
if n != nExpected {
t.Fatalf("unexpected n; got %d; want %d", n, nExpected)
}
}
// Notice: test description along with t.Helper is a nice combo
// first chars match
f("foobar", "foo", 0)
// middle chars match
f("foobar", "bar", 3)
// no match
f("foobar", "baz", -1)
}- f() doesn’t accept t *testing.T arg (it can use the arg from the outer test function)
- The first line inside f() is [t.Helper()](https://pkg.go.dev/testing#T.Helper) call
- t.Helper prints the line with the corresponding f() call when some test fails
- So you do not need to name your test scenarios
- Instead you can use code comments with full explanation & context
