[GH-6798] added a new api endpoint to get the bulk reactions for posts (#10049)

* 6798 added a new api to get the bulk reactions for posts

* 6798 added the permsission check before getting the reactions

* GH-6798 added a new app function for the new endpoint

* 6798 added a store method to get reactions for multiple posts

* 6798 connected the app function with the new store function

* 6798 fixed the review comments

api4/reaction_test.go

@@ -567,3 +567,85 @@ func TestDeleteReaction(t *testing.T) {
 		}
 	})
 }
+
+func TestGetBulkReactions(t *testing.T) {
+	th := Setup().InitBasic()
+	defer th.TearDown()
+	Client := th.Client
+	userId := th.BasicUser.Id
+	user2Id := th.BasicUser2.Id
+	post1 := &model.Post{UserId: userId, ChannelId: th.BasicChannel.Id, Message: "zz" + model.NewId() + "a"}
+	post2 := &model.Post{UserId: userId, ChannelId: th.BasicChannel.Id, Message: "zz" + model.NewId() + "a"}
+	post3 := &model.Post{UserId: userId, ChannelId: th.BasicChannel.Id, Message: "zz" + model.NewId() + "a"}
+
+	post4 := &model.Post{UserId: user2Id, ChannelId: th.BasicChannel.Id, Message: "zz" + model.NewId() + "a"}
+	post5 := &model.Post{UserId: user2Id, ChannelId: th.BasicChannel.Id, Message: "zz" + model.NewId() + "a"}
+
+	post1, _ = Client.CreatePost(post1)
+	post2, _ = Client.CreatePost(post2)
+	post3, _ = Client.CreatePost(post3)
+	post4, _ = Client.CreatePost(post4)
+	post5, _ = Client.CreatePost(post5)
+
+	expectedPostIdsReactionsMap := make(map[string][]*model.Reaction)
+	expectedPostIdsReactionsMap[post1.Id] = []*model.Reaction{}
+	expectedPostIdsReactionsMap[post2.Id] = []*model.Reaction{}
+	expectedPostIdsReactionsMap[post3.Id] = []*model.Reaction{}
+	expectedPostIdsReactionsMap[post5.Id] = []*model.Reaction{}
+
+	userReactions := []*model.Reaction{
+		{
+			UserId:    userId,
+			PostId:    post1.Id,
+			EmojiName: "happy",
+		},
+		{
+			UserId:    userId,
+			PostId:    post1.Id,
+			EmojiName: "sad",
+		},
+		{
+			UserId:    userId,
+			PostId:    post2.Id,
+			EmojiName: "smile",
+		},
+		{
+			UserId:    user2Id,
+			PostId:    post4.Id,
+			EmojiName: "smile",
+		},
+	}
+
+	for _, userReaction := range userReactions {
+		reactions := expectedPostIdsReactionsMap[userReaction.PostId]
+		if result := <-th.App.Srv.Store.Reaction().Save(userReaction); result.Err != nil {
+			t.Fatal(result.Err)
+		} else {
+			reactions = append(reactions, result.Data.(*model.Reaction))
+
+		}
+		expectedPostIdsReactionsMap[userReaction.PostId] = reactions
+	}
+
+	postIds := []string{post1.Id, post2.Id, post3.Id, post4.Id, post5.Id}
+
+	t.Run("get-reactions", func(t *testing.T) {
+		postIdsReactionsMap, resp := Client.GetBulkReactions(postIds)
+		CheckNoError(t, resp)
+
+		assert.ElementsMatch(t, expectedPostIdsReactionsMap[post1.Id], postIdsReactionsMap[post1.Id])
+		assert.ElementsMatch(t, expectedPostIdsReactionsMap[post2.Id], postIdsReactionsMap[post2.Id])
+		assert.ElementsMatch(t, expectedPostIdsReactionsMap[post3.Id], postIdsReactionsMap[post3.Id])
+		assert.ElementsMatch(t, expectedPostIdsReactionsMap[post4.Id], postIdsReactionsMap[post4.Id])
+		assert.ElementsMatch(t, expectedPostIdsReactionsMap[post5.Id], postIdsReactionsMap[post5.Id])
+		assert.Equal(t, expectedPostIdsReactionsMap, postIdsReactionsMap)
+
+	})
+
+	t.Run("get-reactions-as-anonymous-user", func(t *testing.T) {
+		Client.Logout()
+
+		_, resp := Client.GetBulkReactions(postIds)
+		CheckUnauthorizedStatus(t, resp)
+	})
+}