Lesson 4 - PHPUnit DataProvider and BestPractices
In the previous lesson, PHP Testing - Finishing Unit Tests, we covered a class representing a simple calculator with unit tests. We gained an overview of assert methods and learned to test exceptions. Today, in PHPUnit, we're going to learn to use another annotation to help us follow the DRY principle and we'll mention the best practices for testing in PHP.
DataProvider
We already know the @expectedException
annotation that allows us
to test that a given test triggered a given exception. In our tests, we'll often
encounter a situation that we write a test and want to run the same test on
different data to see that different inputs will pass. Creating methods for each
input, that would have the same body and differ only in data, would be a
violation of the DRY principle (Don't Repeat
Yourself).
To show this example in practice, let's consider our calculator has a
sin()
method, which accepts an angle in radians and returns the
value of the sine function for that angle. The method implementation in the
calculator could be as follows (remember this is an example of a class method
that we're going to test here, so we can feel free to just call the already
existing PHP function):
public function sine($angle) { return sin($angle); }
In the tests, it'd be a good idea to test some extreme values, values of
right angles, negative values, zero... you know
Consider we want to test the method using degrees and not radians. We'll do that to need to call some extra methods or even use other objects (dependencies) to get the output:
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In the tutorial, we'll learn to use the @dataProvider annotation, test private and protected methods, and mention best practices for PHP testing.
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