4, 'b' => 5], 'b'], [0, [0, 1], 0], [1, [1, 2], 0], [null, [null], 0], ]; } public function testAtThrowsForOutOfBoundKey(): void { $this->expectException(Exception\InvariantViolationException::class); $this->expectExceptionMessage('Key (5) is out-of-bounds.'); Arr\at([], 5); } }