40.话题订阅（一）

TDD 构建 Laravel 论坛笔记 /

本系列文章为laracasts.com 的系列视频教程——Let's Build A Forum with Laravel and TDD 的学习笔记。若喜欢该系列视频，可去该网站订阅后下载该系列视频， 支持正版 ；

视频源码地址：github.com/laracasts/Lets-Build-a-...；

本项目为一个 forum（论坛）项目，与本站的第二本实战教程《Laravel 教程 - Web 开发实战进阶》类似，可互相参照。

本节说明

对应视频教程第 40 小节：Thread Subscriptions(Part 1)

本节内容

在接下里的几个章节中，我们来完成话题订阅的功能：当你订阅了的话题有新回复时，你将会收到提醒。首先我们来建立测试逻辑：
forum\tests\Unit\ThreadTest.php

    .
    .
    /** @test */
    public function a_thread_can_be_subscribed_to()
    {
        // Given we have a thread
        // And an authenticated user
        // When the user subscribes to the thread
        // Then we should be able to fetch all threads that the user has subscribed to.
    }
}

根据测试逻辑填充代码：

    .
    .
    /** @test */
    public function a_thread_can_be_subscribed_to()
    {
        // Given we have a thread
        $thread = create('App\Thread');

        // And an authenticated user
        $this->signIn();

        // When the user subscribes to the thread
        $thread->subscribe();

        // Then we should be able to fetch all threads that the user has subscribed to.
        $thread->subscriptions()->where('user_id',auth()->id())->get();
    }
}

现在我们的测试是不通过的，因为我们需要定义subscribe()和subscriptions()
forum\app\Thread.php

    .
    .
    public function subscribe()
    {

    }

    public function subscriptions()
    {
        return $this->hasMany(ThreadSubscription::class);
    }
}

建立ThreadSubscription模型：

$ php artisan make:model ThreadSubscription -m

修改迁移文件，建立表结构：
forum\database\migrations{timestamp}_create_thread_subscriptions_table.php

<?php

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateThreadSubscriptionsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('thread_subscriptions', function (Blueprint $table) {
            $table->increments('id');
            $table->unsignedInteger('user_id');
            $table->unsignedInteger('thread_id');
            $table->timestamps();

            $table->foreign('thread_id')
                ->references('id')
                ->on('threads')
                ->onDelete('cascade');
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('thread_subscriptions');
    }
}

注意，我们在此处启用了外键约束。

运行数据库迁移：

$ php artisan migrate

现在我们来运行测试：
file
测试通过，但是我们的测试逻辑并不严谨，我们需要完善它：

    .
    .
    /** @test */
    public function a_thread_can_be_subscribed_to()
    {
        // Given we have a thread
        $thread = create('App\Thread');

        // And an authenticated user
        $this->signIn();

        // When the user subscribes to the thread
        $thread->subscribe();

        // Then we should be able to fetch all threads that the user has subscribed to.
        $this->assertEquals(
            1,
            $thread->subscriptions()->where('user_id',auth()->id())->count()
        );
    }
}

运行测试：
file
测试未通过，因为我们还没有定义subscribe()方法：
forum\app\Thread.php

    .
    .
    public function subscribe($userId = null)
    {
        $this->subscriptions()->create([
           'user_id' => $userId ?: auth()->id()
        ]);

        return $this;
    }
    .
    .

运行测试：
file
批量赋值错误，我们需要为ThreadSubscription模型设置可更新属性：
forum\app\ThreadSubscription.php

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class ThreadSubscription extends Model
{
    protected $guarded =[];
}

再次运行测试：
file
我们可以传参给subscribe()方法，所以我们的测试可以稍微进行下修改：

    .
    .
    /** @test */
    public function a_thread_can_be_subscribed_to()
    {
        // Given we have a thread
        $thread = create('App\Thread');

        // When the user subscribes to the thread
        $thread->subscribe($userId = 1);

        // Then we should be able to fetch all threads that the user has subscribed to.
        $this->assertEquals(
            1,
            $thread->subscriptions()->where('user_id',$userId)->count()
        );
    }
}

再次运行测试，仍然通过：
file
现在我们可以继续前进了。既然已经有了订阅的测试，理所应当也要有取消订阅的测试。我们来建立该测试：
forum\tests\Unit\ThreadTest.php

    .
    .
    /** @test */
    public function a_thread_can_be_unsubscribed_from()
    {
        // Given we have a thread
        $thread = create('App\Thread');

        // And a user who is subscribed to the thread
        $thread->subscribe($userId = 1);

        $thread->unsubscribe($userId);

        $this->assertCount(0,$thread->subscriptions);
    }
}

接下来新建unsubscribe()方法：
forum\app\Thread.php

    .
    .
    public function subscribe($userId = null)
    {
        $this->subscriptions()->create([
           'user_id' => $userId ?: auth()->id()
        ]);

        return $this;
    }

    public function unsubscribe($userId = null)
    {
        $this->subscriptions()
            ->where('user_id',$userId ?: auth()->id())
            ->delete();
    }
    .
    .

运行测试：
file
最后，我们来运行一下全部测试：
file