PHPUnit genrates invalid mock code when false is in a union e.g. false|int

[olvlvl]

Q	A
PHPUnit version	9.5.6
PHP version	8.0.8
Installation Method	Composer

Summary

PHPUnit generates invalid mock code when the type false is used in a union e.g. false|int.

Current behavior

The following code is generated:

declare(strict_types=1);

class false|int
{
}

class Mock_false|int_189b4275 extends false|int implements PHPUnit\Framework\MockObject\MockObject
{
    use \PHPUnit\Framework\MockObject\Api;
    use \PHPUnit\Framework\MockObject\Method;
    use \PHPUnit\Framework\MockObject\MockedCloneMethod;
}

How to reproduce

Here's an example class:

<?php

namespace Dummy;

class Sample
{
    public function doSomething(): false|int
    {
        return false;
    }
}

Here's an example test:

<?php

namespace Tests\Dummy;

use Dummy\Sample;
use PHPUnit\Framework\TestCase;

class SampleTest extends TestCase
{
    public function testExec()
    {
        $mock = $this->createMock(Sample::class);

        $mock->doSomething("hello");
    }
}

Expected behavior

The code for the mock is generated correctly.

Note

Using bool|int fixes the issue, but it changes the meaning of the function, because it will never return true. Besides, false|int is a valid unit type.

[sebastianbergmann]

Thank you for reporting this. This only happens when you create a test double and then do not configure a return value for a method that returns *|false.

[olvlvl]

The following code works indeed:

class SampleTest extends TestCase
{
    public function testExec()
    {
        $mock = $this->createMock(Sample::class);
        $mock->method('doSomething')->willReturn(false, 123);

        $this->assertFalse($mock->doSomething("hello"));
        $this->assertEquals(123, $mock->doSomething("hello"));
    }
}

But how's one supposed to know? Could PHPunit display an error message instead of generating invalid code?

[sebastianbergmann]

I do not understand what you are asking. The issue you reported has been fixed in fe06cbe.

[olvlvl]

Sorry, I read your message and I missed this bit: