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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.


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:


...End of the preview...

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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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Article has been written for you by David Capka
The author is a programmer, who likes web technologies and being the lead/chief article writer at He shares his knowledge with the community and is always looking to improve. He believes that anyone can do what they set their mind to.
Unicorn university The author learned IT at the Unicorn University - a prestigious college providing education on IT and economics.
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