iter\IterTest::testAssertIterableFails PHP Method

    public function testAssertIterableFails(callable $fn, $expectedMessage)
    {
        $this->setExpectedException(\InvalidArgumentException::class, $expectedMessage);
        $ret = $fn();
        // For generators the body will not be run until the first operation
        if ($ret instanceof \Generator) {
            $ret->rewind();
        }
    }