How to use data providers in PHPUnit tests?

@scotty_walker 

Data providers in PHPUnit allow you to run a test method multiple times with different sets of data. Here's how you can use data providers in PHPUnit tests:

1. Define a data provider method: Create a method in your test case class that returns an array of data sets. Each data set will be passed as arguments to the test method when it is executed. The data provider method must be annotated with the @dataProvider annotation and use a unique name to identify the data provider.

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class MyTest extends PHPUnitFrameworkTestCase
{
    /**
     * @dataProvider additionProvider
     */
    public function testAddition($a, $b, $expected)
    {
        $result = $a + $b;
        $this->assertEquals($expected, $result);
    }

    public function additionProvider()
    {
        return [
            [2, 3, 5],
            [0, 0, 0],
            [-3, -5, -8],
        ];
    }
}

1. Write the test method: Write the test method that will receive the data sets provided by the data provider. The test method should accept parameters matching the data set structure defined in the data provider. Use these parameters to perform your assertions.
2. Execute the test: Run your PHPUnit tests as you normally would. The test method annotated with @dataProvider will be executed multiple times, once for each data set returned by the data provider method. Assertions within the test method will be checked against each set of data.

In the example above, the testAddition method will be executed three times, once for each data set in the additionProvider data provider method. It will perform the addition operation with the provided $a and $b values and assert that the result matches the expected value.

By using data providers, you can easily test multiple cases with different input values without duplicating code or writing separate test methods for each case.