From aa47b4633f18eed917c70263d139376f15d8778c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alejandro=20Garc=C3=ADa=20Montoro?=
 <alejandro.garciamontoro@gmail.com>
Date: Wed, 25 Mar 2020 10:24:42 +0100
Subject: [PATCH] MM-23508: Fix plugin API's GetPostsForChannel (#14125)

Add a test checking the basic behaviour of the function
---
 app/plugin_api.go      |  2 +-
 app/plugin_api_test.go | 43 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/app/plugin_api.go b/app/plugin_api.go
index 34697e69af..c1653e426c 100644
--- a/app/plugin_api.go
+++ b/app/plugin_api.go
@@ -521,7 +521,7 @@ func (api *PluginAPI) GetPostsBefore(channelId, postId string, page, perPage int
 }
 
 func (api *PluginAPI) GetPostsForChannel(channelId string, page, perPage int) (*model.PostList, *model.AppError) {
-	return api.app.GetPostsPage(model.GetPostsOptions{ChannelId: channelId, Page: perPage, PerPage: page})
+	return api.app.GetPostsPage(model.GetPostsOptions{ChannelId: channelId, Page: page, PerPage: perPage})
 }
 
 func (api *PluginAPI) UpdatePost(post *model.Post) (*model.Post, *model.AppError) {
diff --git a/app/plugin_api_test.go b/app/plugin_api_test.go
index 737afbf5a7..52b443e22f 100644
--- a/app/plugin_api_test.go
+++ b/app/plugin_api_test.go
@@ -1409,3 +1409,46 @@ func TestApiMetrics(t *testing.T) {
 		metricsMock.AssertExpectations(t)
 	})
 }
+
+func TestPluginAPIGetPostsForChannel(t *testing.T) {
+	require := require.New(t)
+
+	th := Setup(t).InitBasic()
+	defer th.TearDown()
+	api := th.SetupPluginAPI()
+
+	numPosts := 10
+
+	// GetPostsForChannel returns posts ordered with the most recent first, so we
+	// need to invert the expected slice, the oldest post being BasicPost
+	expectedPosts := make([]*model.Post, numPosts)
+	expectedPosts[numPosts-1] = th.BasicPost
+	for i := numPosts - 2; i >= 0; i-- {
+		expectedPosts[i] = th.CreatePost(th.BasicChannel)
+	}
+	// CreatePost does not add Metadata, but initializes the structure. GetPostsForChannel
+	// returns nil for an empty Metadata, so we need to match that behaviour
+	for _, post := range expectedPosts {
+		post.Metadata = nil
+	}
+
+	postList, err := api.GetPostsForChannel(th.BasicChannel.Id, 0, 0)
+	require.Nil(err)
+	require.Nil(postList.ToSlice())
+
+	postList, err = api.GetPostsForChannel(th.BasicChannel.Id, 0, numPosts/2)
+	require.Nil(err)
+	require.Equal(expectedPosts[:numPosts/2], postList.ToSlice())
+
+	postList, err = api.GetPostsForChannel(th.BasicChannel.Id, 1, numPosts/2)
+	require.Nil(err)
+	require.Equal(expectedPosts[numPosts/2:], postList.ToSlice())
+
+	postList, err = api.GetPostsForChannel(th.BasicChannel.Id, 2, numPosts/2)
+	require.Nil(err)
+	require.Nil(postList.ToSlice())
+
+	postList, err = api.GetPostsForChannel(th.BasicChannel.Id, 0, numPosts+1)
+	require.Nil(err)
+	require.Equal(expectedPosts, postList.ToSlice())
+}