Add plugin API for UploadFile method (#9684)

* Add plugin API for UploadFile method

* Add minimum server version documentation to plugin API UploadFile function

* Reorganize some imports

app/file_test.go

@@ -107,6 +107,30 @@ func TestDoUploadFile(t *testing.T) {
 	}
 }
 
+func TestUploadFile(t *testing.T) {
+	th := Setup()
+	defer th.TearDown()
+
+	channelId := model.NewId()
+	filename := "test"
+	data := []byte("abcd")
+
+	info1, err := th.App.UploadFile(data, channelId, filename)
+	if err != nil {
+		t.Fatal(err)
+	} else {
+		defer func() {
+			<-th.App.Srv.Store.FileInfo().PermanentDelete(info1.Id)
+			th.App.RemoveFile(info1.Path)
+		}()
+	}
+
+	if info1.Path != fmt.Sprintf("%v/teams/noteam/channels/%v/users/nouser/%v/%v",
+		time.Now().Format("20060102"), channelId, info1.Id, filename) {
+		t.Fatal("stored file at incorrect path", info1.Path)
+	}
+}
+
 func TestGetInfoForFilename(t *testing.T) {
 	th := Setup().InitBasic()
 	defer th.TearDown()