v8.0 module release (#22975)

https://mattermost.atlassian.net/browse/MM-52079

```release-note
We upgrade the module version to 8.0. The new module path is github.com/mattermost-server/server/v8.
```


Co-authored-by: Doug Lauder <wiggin77@warpmail.net>

server/model/post_list_test.go

@@ -0,0 +1,148 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestPostListJson(t *testing.T) {
+	pl := PostList{}
+	p1 := &Post{Id: NewId(), Message: NewId()}
+	pl.AddPost(p1)
+	p2 := &Post{Id: NewId(), Message: NewId()}
+	pl.AddPost(p2)
+
+	pl.AddOrder(p1.Id)
+	pl.AddOrder(p2.Id)
+
+	js, err := pl.ToJSON()
+	assert.NoError(t, err)
+
+	var rpl PostList
+	err = json.Unmarshal([]byte(js), &rpl)
+	assert.NoError(t, err)
+
+	assert.Equal(t, p1.Message, rpl.Posts[p1.Id].Message, "failed to serialize p1 message")
+	assert.Equal(t, p2.Message, rpl.Posts[p2.Id].Message, "failed to serialize p2 message")
+	assert.Equal(t, p2.Id, rpl.Order[1], "failed to serialize p2 Id")
+}
+
+func TestPostListExtend(t *testing.T) {
+	p1 := &Post{Id: NewId(), Message: NewId()}
+	p2 := &Post{Id: NewId(), Message: NewId()}
+	p3 := &Post{Id: NewId(), Message: NewId()}
+
+	l1 := PostList{}
+	l1.AddPost(p1)
+	l1.AddOrder(p1.Id)
+	l1.AddPost(p2)
+	l1.AddOrder(p2.Id)
+
+	l2 := PostList{}
+	l2.AddPost(p3)
+	l2.AddOrder(p3.Id)
+
+	l2.Extend(&l1)
+
+	// should not changed l1
+	assert.Len(t, l1.Posts, 2)
+	assert.Len(t, l1.Order, 2)
+
+	// should extend l2
+	assert.Len(t, l2.Posts, 3)
+	assert.Len(t, l2.Order, 3)
+
+	// should extend the Order of l2 correctly
+	assert.Equal(t, l2.Order[0], p3.Id)
+	assert.Equal(t, l2.Order[1], p1.Id)
+	assert.Equal(t, l2.Order[2], p2.Id)
+
+	// extend l2 again
+	l2.Extend(&l1)
+	// extending l2 again should not changed l1
+	assert.Len(t, l1.Posts, 2)
+	assert.Len(t, l1.Order, 2)
+
+	// extending l2 again should extend l2
+	assert.Len(t, l2.Posts, 3)
+	assert.Len(t, l2.Order, 3)
+
+	// p3 could be last unread
+	p4 := &Post{Id: NewId(), Message: NewId()}
+	p5 := &Post{Id: NewId(), RootId: p1.Id, Message: NewId()}
+	p6 := &Post{Id: NewId(), RootId: p1.Id, Message: NewId()}
+
+	// Create before and after post list where p3 could be last unread
+
+	// Order has 2 but Posts are 4 which includes additional 2 comments (p5 & p6) to parent post (p1)
+	beforePostList := PostList{
+		Order: []string{p1.Id, p2.Id},
+		Posts: map[string]*Post{p1.Id: p1, p2.Id: p2, p5.Id: p5, p6.Id: p6},
+	}
+
+	// Order has 3 but Posts are 4 which includes 1 parent post (p1) of comments (p5 & p6)
+	afterPostList := PostList{
+		Order: []string{p4.Id, p5.Id, p6.Id},
+		Posts: map[string]*Post{p1.Id: p1, p4.Id: p4, p5.Id: p5, p6.Id: p6},
+	}
+
+	beforePostList.Extend(&afterPostList)
+
+	// should not changed afterPostList
+	assert.Len(t, afterPostList.Posts, 4)
+	assert.Len(t, afterPostList.Order, 3)
+
+	// should extend beforePostList
+	assert.Len(t, beforePostList.Posts, 5)
+	assert.Len(t, beforePostList.Order, 5)
+
+	// should extend the Order of beforePostList correctly
+	assert.Equal(t, beforePostList.Order[0], p1.Id)
+	assert.Equal(t, beforePostList.Order[1], p2.Id)
+	assert.Equal(t, beforePostList.Order[2], p4.Id)
+	assert.Equal(t, beforePostList.Order[3], p5.Id)
+	assert.Equal(t, beforePostList.Order[4], p6.Id)
+}
+
+func TestPostListSortByCreateAt(t *testing.T) {
+	pl := PostList{}
+	p1 := &Post{Id: NewId(), Message: NewId(), CreateAt: 2}
+	pl.AddPost(p1)
+	p2 := &Post{Id: NewId(), Message: NewId(), CreateAt: 1}
+	pl.AddPost(p2)
+	p3 := &Post{Id: NewId(), Message: NewId(), CreateAt: 3}
+	pl.AddPost(p3)
+
+	pl.AddOrder(p1.Id)
+	pl.AddOrder(p2.Id)
+	pl.AddOrder(p3.Id)
+
+	pl.SortByCreateAt()
+
+	assert.EqualValues(t, pl.Order[0], p3.Id)
+	assert.EqualValues(t, pl.Order[1], p1.Id)
+	assert.EqualValues(t, pl.Order[2], p2.Id)
+}
+
+func TestPostListToSlice(t *testing.T) {
+	pl := PostList{}
+	p1 := &Post{Id: NewId(), Message: NewId(), CreateAt: 2}
+	pl.AddPost(p1)
+	p2 := &Post{Id: NewId(), Message: NewId(), CreateAt: 1}
+	pl.AddPost(p2)
+	p3 := &Post{Id: NewId(), Message: NewId(), CreateAt: 3}
+	pl.AddPost(p3)
+
+	pl.AddOrder(p1.Id)
+	pl.AddOrder(p2.Id)
+	pl.AddOrder(p3.Id)
+
+	want := []*Post{p1, p2, p3}
+
+	assert.Equal(t, want, pl.ToSlice())
+}