I am doing some unit testing with PHP. I got stuck on an error that the fluent interface of PHPUnit requires an intermediate variable. What is the reason for this behavior?
See MyTests::works vs. MyTests::fails:
<?php use PHPUnit\Framework\TestCase; interface SomeInterface { public function someMethod(); } class SomeService { public function __construct( private SomeInterface $interface ) { } public function testMethod() { $this->interface->someMethod(); } } class MyTests extends TestCase { // Using fluent-interface with intermediate variable works public function works() { $mock = $this->createMock(SomeInterface::class); $mock->expects($this->once()) ->method("someMethod"); $service = new SomeService($mock); $service->testMethod(); } // Using fluent-interface without intermediate variable fails public function fails() { // Fails: TypeError: SomeService::__construct(): Argument #1 ($interface) must be of type SomeInterface, PHPUnit\Framework\MockObject\InvocationStubberImplementation given, called in /xxx/MyTests.php on line 25 $mock = $this->createMock(SomeInterface::class) ->expects($this->once()) ->method("someMethod"); $service = new SomeService($mock); $service->testMethod(); } } ?> I already found the same question asked before (Mock class with fluent interface in Phpunit), but I am searching for the why not for the fix.
