Better way to test Laravel validation errors

If I want to validate that given input is a valid array, I used to write my tests something like this.

$this->postJson("/api/items", [
    'items' => 'not-an-array'
])
  ->assertStatus(422)
  ->assertJsonValidationErrors('items');

This gives a false positive result in some situations. Test does not know which validation rule is failing.

Here is the better way to write your test.

$this->postJson("/api/items", [
    'items' => 'not-an-array'
])
  ->assertStatus(422)
  ->assertJsonValidationErrors(['items' => 'array']);

This assert if the array keyword exist in the validation error message. Now I am confident that my test is passing because items is not an array.