php-testing

PHP Testing with PHPUnit

Before writing code

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PHPUnit Fundamentals

Test Class Structure

• Test classes extend PHPUnit\Framework\TestCase
• Test methods prefixed with test or annotated #[Test]
• setUp() — runs before each test
• tearDown() — runs after each test
• setUpBeforeClass() / tearDownAfterClass() — per-class lifecycle

Assertions

Common assertions:

• assertEquals($expected, $actual) — loose comparison
• assertSame($expected, $actual) — strict comparison (type + value)
• assertTrue($value) / assertFalse($value)
• assertNull($value) / assertNotNull($value)
• assertInstanceOf($class, $object)
• assertCount($count, $array)
• assertArrayHasKey($key, $array)
• assertStringContainsString($needle, $haystack)
• expectException($class) — exception testing

Data Providers

Supply multiple test cases to a single test method:

• #[DataProvider('providerName')] attribute (PHPUnit 10+)
• Provider method returns array of arrays (each inner array = one test case)
• Reduces test duplication for parameterized testing

Test Doubles

Mocks

Verify behavior — assert that methods were called with expected arguments:

• $this->createMock(SomeClass::class)
• $mock->expects($this->once())->method('save')->with($entity)
• $mock->expects($this->never())->method('delete')

Stubs

Provide canned responses — no behavior verification:

• $stub->method('getById')->willReturn($entity)
• $stub->method('getList')->willReturn($searchResults)

Method Return Behaviors

• willReturn($value) — always returns this value
• willReturnMap($map) — returns based on argument mapping
• willReturnCallback($callable) — dynamic return
• willThrowException($exception) — throws on call
• willReturnSelf() — returns the mock (for fluent APIs)

Consecutive Calls