PHP Unit Testing: Tips for Increasing Code Coverage

Methods to improve code coverage in PHP unit testing: Use PHPUnit's --coverage-html option to generate a coverage report. Use the setAccessible method to override private methods and properties. Use assertions to override Boolean conditions. Gain additional code coverage insights with code review tools.

PHP Unit Testing: Tips to Increase Code Coverage

Unit testing is a crucial practice to ensure code quality. Code coverage is a measure of test coverage; the higher the coverage, the higher the confidence. This article will introduce techniques to improve PHPUnit unit test code coverage and provide practical cases.

1. Use the coverage reporting tool

PHPUnit provides the --coverage-html option to generate an HTML report showing the coverage of each file and method. This helps identify uncovered code and guides subsequent improvements.

phpunit --coverage-html=coverage-report

2. Overriding private methods and properties

Private methods and properties are usually difficult to test. You can make them visible to tests using the setAccessible method:

$object->setAccessibleProperty('privateProperty', 'newValue');
$object->setAccessibleMethod('privateMethod', function() { ... });

3. Override conditions using assertions

Assertions are used to verify expected results. Boolean conditions can be overridden using assertions such as assertTrue, assertFalse. For example:

$this->assertTrue($object->isValid());

4. Use a code review tool

Code review tools, such as Scrutinizer CI, can provide additional code coverage insights. It automatically creates coverage reports and prompts for uncovered code.

Practical case

Consider the following code:

class Calculator
{
    public function add($a, $b)
    {
        return $a + $b;
    }
}

We can write a unit test to cover the add method:

class CalculatorTest extends PHPUnit\Framework\TestCase
{
    public function testAdd()
    {
        $calculator = new Calculator();
        $this->assertEquals(5, $calculator->add(2, 3));
    }
}

Passed Using the code coverage report, we see that CalculatorTest only covers part of the add method. We can cover the remaining conditions by asserting $a !== $b:

$this->assertEquals(5, $calculator->add(2, 3));
$this->assertNotEquals(3, $calculator->add(2, 3));

Now, the test coverage will be 100%.

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