Add initial unit test for post.getPostById() (#4910)

* add itinial tests for GetPostById

update per review

fix lint

* add missing comment

2 files changed, 45 insertions, 0 deletions

diff --git a/api/post_test.go b/api/post_test.go
index fd0c0b24b..eb01195db 100644
--- a/api/post_test.go
+++ b/api/post_test.go
@@ -1360,3 +1360,33 @@ func TestSendNotifications(t *testing.T) {
 		t.Fatal("user should have been mentioned")
 	}
 }
+
+func TestGetPostById(t *testing.T) {
+	th := Setup().InitBasic()
+	Client := th.BasicClient
+	channel1 := th.BasicChannel
+
+	time.Sleep(10 * time.Millisecond)
+	post1 := &model.Post{ChannelId: channel1.Id, Message: "yommamma" + model.NewId() + "a"}
+	post1 = Client.Must(Client.CreatePost(post1)).Data.(*model.Post)
+
+	if post, respMetadata := Client.GetPostById(post1.Id, ""); respMetadata.Error != nil {
+		t.Fatal(respMetadata.Error)
+	} else {
+		if len(post.Order) != 1 {
+			t.Fatal("should be just one post")
+		}
+
+		if post.Order[0] != post1.Id {
+			t.Fatal("wrong order")
+		}
+
+		if post.Posts[post.Order[0]].Message != post1.Message {
+			t.Fatal("wrong message from post")
+		}
+	}
+
+	if _, respMetadata := Client.GetPostById("45345435345345", ""); respMetadata.Error == nil {
+		t.Fatal(respMetadata.Error)
+	}
+}
diff --git a/model/client.go b/model/client.go
index 54095fcba..7248ca951 100644
--- a/model/client.go
+++ b/model/client.go
@@ -1483,6 +1483,21 @@ func (c *Client) GetPost(channelId string, postId string, etag string) (*Result,
 	}
 }
 
+// GetPostById returns a post and any posts in the same thread by post id
+func (c *Client) GetPostById(postId string, etag string) (*PostList, *ResponseMetadata) {
+	if r, err := c.DoApiGet(c.GetTeamRoute()+fmt.Sprintf("/posts/%v", postId), "", etag); err != nil {
+		return nil, &ResponseMetadata{StatusCode: r.StatusCode, Error: err}
+	} else {
+		defer closeBody(r)
+		return PostListFromJson(r.Body),
+			&ResponseMetadata{
+				StatusCode: r.StatusCode,
+				RequestId:  r.Header.Get(HEADER_REQUEST_ID),
+				Etag:       r.Header.Get(HEADER_ETAG_SERVER),
+			}
+	}
+}
+
 func (c *Client) DeletePost(channelId string, postId string) (*Result, *AppError) {
 	if r, err := c.DoApiPost(c.GetChannelRoute(channelId)+fmt.Sprintf("/posts/%v/delete", postId), ""); err != nil {
 		return nil, err