t.Fatalf("for .TEST, got %q; want %s", got, caps)
	}

	// case-insensitive
	if got := TypeByExtension(".TesT"); got != custom {
		t.Fatalf("for .TesT, got %q; want %q", got, custom)
	}
}

func TestExtensionsByType(t *testing.T) {
	cleanup := setMimeInit(func() {
		clearMimeTypes()
		setType(".gif", "image/gif")
		setType(".a", "foo/letter")
		setType(".b", "foo/letter")
		setType(".B", "foo/letter")