How to test performance in PHPUnit?

@rollin 

There are several ways to test performance in PHPUnit:

1. Time Assertions: PHPUnit provides the ability to measure the execution time of a specific code block using time assertions. You can use the assertGreaterThanOrEqual() or assertLessThanOrEqual() assertion methods to ensure that the execution time is within an expected range.

Example:

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public function testPerformance()
{
    $start = microtime(true);

    // Code block to be tested

    $end = microtime(true);
    $executionTime = $end - $start;

    $this->assertLessThanOrEqual(1, $executionTime); // Ensure execution time is less than or equal to 1 second
}

1. Code Coverage: PHPUnit also provides code coverage analysis that allows you to measure the code coverage of your tests. This can be an indirect way to measure performance, as code that takes longer to execute will have a higher code coverage.

Example:

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public function testPerformance()
{
    // Code block to be tested

    $coverage = $this->getCodeCoverage(); // Get the code coverage instance
    $coverageData = $coverage->getData(); // Get the coverage data

    $codeCoveragePercentage = $coverageData->getPercentage(); // Calculate the code coverage percentage

    $this->assertGreaterThanOrEqual(80, $codeCoveragePercentage); // Ensure code coverage is at least 80%
}

1. Blackfire Profiler: Blackfire is a profiling tool that integrates with PHPUnit and allows you to measure the performance of your code in detail. It provides insights into CPU usage, memory consumption, and execution time of each method. You can install the Blackfire extension and use the @blackfire annotation to profile specific test methods.

Example:

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/**
 * @blackfire
 */
public function testPerformance()
{
    // Code block to be tested
}

Note: Blackfire requires additional setup and configuration. Refer to the Blackfire documentation for more details.

Whichever method you choose, it is important to establish a performance baseline by running the tests multiple times and comparing the results to identify any performance issues or regressions.