diff --git a/app/Models/Interaction.php b/app/Models/Interaction.php
index 60e14016..671c8ada 100644
--- a/app/Models/Interaction.php
+++ b/app/Models/Interaction.php
@@ -11,6 +11,7 @@ use Illuminate\Database\Eloquent\Model;
  * @property int   play_count
  * @property Song  song
  * @property User  user
+ * @property int id
  */
 class Interaction extends Model
 {
diff --git a/app/Models/Song.php b/app/Models/Song.php
index c37a6c38..605e4e75 100644
--- a/app/Models/Song.php
+++ b/app/Models/Song.php
@@ -352,4 +352,9 @@ class Song extends Model
 
         return compact('bucket', 'key');
     }
+
+    public function __toString()
+    {
+        return $this->id;
+    }
 }
diff --git a/database/factories/ModelFactory.php b/database/factories/ModelFactory.php
index 6c5279ca..90fc6b96 100644
--- a/database/factories/ModelFactory.php
+++ b/database/factories/ModelFactory.php
@@ -52,3 +52,12 @@ $factory->define(App\Models\Playlist::class, function ($faker) {
         'name' => $faker->name,
     ];
 });
+
+$factory->define(\App\Models\Interaction::class, function ($faker) {
+    return [
+        'song_id' => factory(\App\Models\Song::class)->create()->id,
+        'user_id' => factory(\App\Models\User::class)->create()->id,
+        'liked' => $faker->boolean,
+        'play_count' => $faker->randomNumber,
+    ];
+});
diff --git a/tests/Unit/InteractionTest.php b/tests/Unit/InteractionTest.php
new file mode 100644
index 00000000..81d24d1b
--- /dev/null
+++ b/tests/Unit/InteractionTest.php
@@ -0,0 +1,93 @@
+<?php
+
+namespace Tests\Unit;
+
+use App\Events\SongLikeToggled;
+use App\Models\Interaction;
+use App\Models\Song;
+use App\Models\User;
+use Illuminate\Support\Collection;
+use Tests\TestCase;
+
+class InteractionTest extends TestCase
+{
+    /** @test */
+    public function it_can_be_instantiated()
+    {
+        $this->assertInstanceOf(Interaction::class, new Interaction());
+    }
+
+    /** @test */
+    public function it_increases_a_songs_play_count()
+    {
+        // Given an interaction
+        /** @var Interaction $interaction */
+        $interaction = factory(Interaction::class)->create();
+
+        // When I call the method to increases the song's play count
+        Interaction::increasePlayCount($interaction->song, $interaction->user);
+
+        // Then I see the play count is increased
+        /** @var Interaction $interaction */
+        $updatedInteraction = Interaction::find($interaction->id);
+        $this->assertEquals($interaction->play_count + 1, $updatedInteraction->play_count);
+    }
+
+    /** @test */
+    public function it_toggles_like_status()
+    {
+        $this->expectsEvents(SongLikeToggled::class);
+
+        // Given an interaction
+        $interaction = factory(Interaction::class)->create();
+
+        // When I call the method to toggle the song's like status by user
+        Interaction::toggleLike($interaction->song, $interaction->user);
+
+        // Then I see the interaction's like status is toggled
+        /** @var Interaction $interaction */
+        $updatedInteraction = Interaction::find($interaction->id);
+        $this->assertNotSame($interaction->liked, $updatedInteraction->liked);
+    }
+
+    /** @test */
+    public function user_can_like_multiple_songs_at_once()
+    {
+        $this->expectsEvents(SongLikeToggled::class);
+
+        // Given multiple song and a user
+        /** @var Collection $songs */
+        $songs = factory(Song::class, 2)->create();
+        $user = factory(User::class)->create();
+
+        // When I call the method to like songs in batch
+        Interaction::batchLike($songs->pluck('id')->all(), $user);
+
+        // Then I see the songs are all liked
+        $songs->each(function (Song $song) use ($user) {
+            $this->assertTrue(Interaction::whereSongIdAndUserId($song->id, $user->id)->first()->liked);
+        });
+    }
+
+    /** @test */
+    public function user_can_unlike_multiple_songs_at_once()
+    {
+        $this->expectsEvents(SongLikeToggled::class);
+
+        // Given multiple interaction records
+        $user = factory(User::class)->create();
+        /** @var Collection $interactions */
+        $interactions = factory(Interaction::class, 3)->create([
+            'user_id' => $user->id,
+            'liked' => true,
+        ]);
+
+        // When I call the method to like songs in batch
+        Interaction::batchUnlike($interactions->pluck('song.id')->all(), $user);
+
+        // Then I see the songs are all liked
+        $interactions->each(function (Interaction $interaction) {
+            $this->assertFalse(Interaction::find($interaction->id)->liked);
+        });
+    }
+}