Static util testing is most simple way of testing so there’s not much to talk about it.

test('DateTimeFormatter formats correctly to api time', () {
    final dateTime = DateTime(2000, 1, 1);
    final result = DateTimeFormatter.formatToApiTime(dateTime);
    expect(result, '2000-1-1');
});

Here we will also note that test usually have three distinctive sections:

• Given: given some setup and conditions
• When: when something happens
• Then: then we expect the result to be some value

Here’s the same test with that sections explained:

test('DateTimeFormatter formats correctly to api time', () {
    // Given that dateTime is 1st January 2000
    final dateTime = DateTime(2000, 1, 1);

  // When we format to api time
    final result = DateTimeFormatter.formatToApiTime(dateTime);

    // Then we expect that resulting string is 2000-1-1
    expect(result, '2000-1-1');
});

You don’t need to write these comments but it’s a good practice to leave a newline to visually separate these sections.

We’ll explain more testing concepts in further pages as we are explaining how we test interactors and presenters.