EloquentCollection->intersect misbehaves when called with null argument

[jonaslm]

• Laravel Version: 6.5.1
• PHP Version: 7.3
• Database Driver & Version: N/A

Description:

When calling $collection->intersect(null) on an Eloquent Collection the whole $collection is returned. I would expect an error or, possibly, an empty collection to be returned. Note that doing the same thing on a regular base collection returns an empty collection.

We had this happen, causing silent errors (we called intersect with a nonexistant relation as argument, which gets returned as null).

Steps To Reproduce:

Assuming you have an Eloquent Collection $eloquentCollection that isn't empty, simply call

$eloquentCollection->intersect(null);

The entire collection will be returned. Expected behavior would be an error or, possibly, an empty collection. Again, note that doing the same thing on a base collection returns an empty collection.

[driesvints]

Tested this and confirmed. This indeed seems like unwanted behavior. Welcoming prs for this.

[ahinkle]

Hmm, am I missing something here? $collection->intersect(null) returns an empty collection.

framework/tests/Support/SupportCollectionTest.php

Lines 1151 to 1158 in 1bbe552

	/**
	* @dataProvider collectionClassProvider
	*/
	public function testIntersectNull($collection)
	{
	$c = new $collection(['id' => 1, 'first_word' => 'Hello']);
	$this->assertEquals([], $c->intersect(null)->all());
	}

framework/tests/Support/SupportCollectionTest.php

Lines 1160 to 1167 in 1bbe552

	/**
	* @dataProvider collectionClassProvider
	*/
	public function testIntersectCollection($collection)
	{
	$c = new $collection(['id' => 1, 'first_word' => 'Hello']);
	$this->assertEquals(['first_word' => 'Hello'], $c->intersect(new $collection(['first_world' => 'Hello', 'last_word' => 'World']))->all());
	}

[BSN4]

@ahinkle this bug only occurs on Eloquent collection