Google\Cloud\PubSub\Topic::subscribe PHP Method

    public function subscribe($name, array $options = [])
    {
        $subscription = $this->subscriptionFactory($name);
        $subscription->create($options);
        return $subscription;
    }

 public function testSubscribe()
 {
     $subscriptionData = ['name' => 'projects/project-name/subscriptions/subscription-name', 'topic' => 'projects/project-name/topics/topic-name'];
     $this->connection->createSubscription(Argument::withEntry('foo', 'bar'))->willReturn($subscriptionData)->shouldBeCalledTimes(1);
     $topic = new Topic($this->connection->reveal(), 'topic-name', 'project-name');
     $subscription = $topic->subscribe('subscription-name', ['foo' => 'bar']);
     $this->assertInstanceOf(Subscription::class, $subscription);
 }