createMockForIntersectionOfInterfaces() does not automatically register mock object for expectation verification

[rickdenhaan]

Q	A
PHPUnit version	10.4.2
PHP version	8.2.12
Installation Method	Composer

Summary

When creating a mock using $this->createMockForIntersectionOfInterfaces(), the created MockObject is not registered in the test case. Because of this, failing expectations are not triggered when the test completes.

Current behavior

createMockForIntersectionOfInterfaces() does not call registerMockObject, which means failing expectations are not flagged as a test failure.

Expected behavior

createMockForIntersectionOfInterfaces() calls registerMockObject just like createMock() does.

How to reproduce

<?php

use PHPUnit\Framework\TestCase;

class Example
{
    public function __construct(private \Stringable $object)
    {
    }

    public function count(): int
    {
        if ($this->object instanceof \Countable) {
            return $this->object->count();
        }

        return 0;
    }
}

class ExampleTest extends TestCase
{
    public function testCount(): void
    {
        $withCountable = $this->createMockForIntersectionOfInterfaces(
            [
                \Stringable::class,
                \Iterator::class,
                \Countable::class,
            ]
        );

        $withoutCountable = $this->createMockForIntersectionOfInterfaces(
            [
                \Stringable::class,
                \Iterator::class,
            ]
        );

        //$this->registerMockObject($withCountable);
        //$this->registerMockObject($withoutCountable);

        $withCountable->expects(self::once())
                      ->method('count');

        $withoutCountable->expects(self::never())
                         ->method(self::anything());

        // lazy copy/pasting: one of these should be withCountable.
        // $withCountable is unused, therefore the count method is never called and the expectation should fail
        (new Example($withoutCountable))->count();
        (new Example($withoutCountable))->count();
    }
}

Running PHPUnit outputs:

PHPUnit 10.4.2 by Sebastian Bergmann and contributors.

Runtime:       PHP 8.2.12


This test did not perform any assertions
Time: 00:00.012, Memory: 8.00 MB

There was 1 risky test:

1) ExampleTest::testCount
This test did not perform any assertions

/path/to/ExampleTest.php:23

OK, but there were issues!
Tests: 1, Assertions: 0, Risky: 1.

Note: PHPUnit exits with exit code 0, meaning if this is the only "failing" test, CI will happily proceed.

Manually registering the mocks (something createMock() does automatically for you) by enabling the registerMockObject lines works as expected:

[...]
        $this->registerMockObject($withCountable);
        $this->registerMockObject($withoutCountable);
[...]

PHPUnit 10.4.2 by Sebastian Bergmann and contributors.

Runtime:       PHP 8.2.12


Expectation failed for method name is "count" when invoked 1 time.
Method was expected to be called 1 time, actually called 0 times.

Time: 00:00.014, Memory: 8.00 MB

There was 1 failure:

1) ExampleTest::testCount
Expectation failed for method name is "count" when invoked 1 time.
Method was expected to be called 1 time, actually called 0 times.

FAILURES!
Tests: 1, Assertions: 1, Failures: 1.

Now the expectation causes a test failure and PHPUnit exits with exit code 1, interrupting CI flow as it should.

[rickdenhaan]

@sebastianbergmann That was quick, thanks for picking it up on such short notice!