Why are concrete statements better than general statements in PHPUnit?

Question

Please excuse my ignorance; I'm still new to unit testing.

Can someone explain why ..

$this->assertGreaterThan( 2, $result );

.. better than..

$this->assertTrue( $result > 2 );

.. (as well as all other specific approval methods)?

Thanks!

Answer 1

If you showed your mom / dad / uncle, then assertGreaterThan much more intuitive. Plus a failed message for isGreaterThan will be much better

 "1 was not greater than 2" 

or

 "false was not true" 

Which one is more expressive?

Answer 2

Actually, the best way provides better readability and better error messages: use PHPUnit based on approval functions or the Hamcrest Library .

 assertThat(count($users), greaterThan(2)); >> Expected: greater than 2 >> but: was 1 

or

 assertThat($users, arrayWithSize(greaterThan(2))); >> Expected: array with size greater than 2 >> but: was array with size 1 

You can always provide a readable error message with any statement by adding a line as the first parameter to the statement methods or the Hamcrest assertThat function or the third parameter to the PHPUnit assertThat function:

 self::assertTrue('At least one user found', !empty($users)); >> At least one user found >> Expected: true >> but: false 

or

 assertThat('At least one user found', !empty($users), is(true)); >> At least one user found >> Expected: true >> but: false 

Answer 3

better than...

Who is speaking? Both are good. In both cases, the readability is different, but none of them is especially great. You can improve it with some variable extraction:

 $minimumValue = 2; $this->assertGreaterThan($minimumValue, $result); 

and

 $resultGreaterThanMinimumValue = $result > 2; $this->assertTrue($resultGreaterThanMinimumValue); 

This is still not ideal (since these statements are not readable like a sentence in English), but neither of these two approaches is better.