React\Promise\FunctionReduceTest::shouldReduceEmptyInputWithInitialValue PHP Method

    public function shouldReduceEmptyInputWithInitialValue()
    {
        $mock = $this->createCallableMock();
        $mock->expects($this->once())->method('__invoke')->with($this->identicalTo(1));
        reduce([], $this->plus(), 1)->then($mock);
    }