Freezing time

01 Pin the clock, then move it when the date matters

Freeze at the start, before the code writes a timestamp. travel() is for the case where an hour has to pass.

it('expires the payment link after an hour', function () {
    $this->freezeTime();

    $invoice = Invoice::factory()->issued()->create();

    $this->actingAs($invoice->team->owner)
        ->post('/invoices/'.$invoice->id.'/link');

    $this->travel(61)->minutes();

    $this->get('/pay/'.$invoice->fresh()->pay_token)
        ->assertForbidden();
});

The snippet on freezing time shows freezeTime(), travel() and travelTo() on their own, with a password reset token.

Freeze time in tests.

Call travel() only in the test that needs the clock to move. A frozen clock in every test hides a bug that depends on time passing.

02 Assert a timestamp only after the clock is pinned

sent_at is written with now(). Without freezeTime(), the assertion has to allow a range, and a range hides a bug that writes yesterday. Freeze, act, then compare the column to the frozen instant.

it('records when the invoice was sent', function () {
    $this->freezeTime();

    $invoice = Invoice::factory()->issued()->create();

    $this->actingAs($invoice->team->owner)
        ->post('/invoices/'.$invoice->id.'/send')
        ->assertRedirect();

    expect($invoice->fresh()->sent_at->equalTo(now()))->toBeTrue();
});

travel() comes after that post when the test is about expiry, as in the link above. It does not belong in this one. The sent_at test wants a single instant, and now() inside the expectation is that same instant because the clock is still frozen.

freezeTime() also freezes Carbon inside the factory. An issued_on of now() in the factory is the same instant as the assertion. If the test needs a date in the past, pass that date in the factory and leave the clock frozen. travel() before the post would make sent_at match the travelled time, and the test would still pass for the wrong reason.