Using Log::spy with channels

[Synchro]

I have a FormRequest that logs validation error details:

protected function failedValidation(Validator $validator)
    {
        Log::channel('logistics')->info('Validation failed. Submitted serials:', [
            'contents' => $this->input('contents'),
        ]);
...

I want to test that this logs correctly, so in a test I'm doing this:

        Log::spy();
        $this->postJson(
            'logistics/delivery',
            [
                'location_id' => $location->uuid,
                'contents'    => [
                    $case1->serial,
                ],
            ]
        )
            ->assertUnprocessable();
        Log::shouldHaveReceived('info')
            ->withArgs(function ($message, $context) use ($case1) {
                $this->assertStringContainsString('Validation failed. Submitted serials:', $message);
                $this->assertArrayHasKey('contents', $context);
                $this->assertEquals([$case1->serial], $context['contents']);
                return true;
            });

This fails in the FormRequest with "Call to a member function info() on null" because after being mocked with spy, Log::channel('logistics') returns null, I assume because the mocked Log facade contains no channels, but the net result is that it only fails when testing; it works fine normally.

I'm using Log::spy with Log::shouldHaveReceived instead of Log::shouldReceive because there may be other logging calls during the test run, and they create ambiguity that can be avoided with spy.

I also tried spying on the channel specifically, using Log::channel('logistics')->spy();, but that doesn't exist.

If I remove the use of channel() in both code and test, it works fine.

How should I test this?

[Synchro]

I found that the easiest way to deal with this is to use timacdonald/log-fake, which allows tests on log channels to work properly.