MM-52804 - Implement SendPushNotification plugin api method (#24273)

* add SendPushNotification plugin api method

* lint; add testing.Short bc of the sleep

* add interface and generated layers

* add fields to PluginPushNotification; generate mocks

* SendPushNotification -> SendPluginPushNotification; improved comments

* more comments; fix test

* send api.ctx

server/channels/app/plugin_api_test.go

@@ -19,6 +19,7 @@ import (
 	"path"
 	"path/filepath"
 	"strings"
+	"sync"
 	"testing"
 	"time"
 
@@ -2204,3 +2205,91 @@ func TestConfigurationWillBeSavedHook(t *testing.T) {
 		}, newCfg.PluginSettings.Plugins["custom_plugin"])
 	})
 }
+
+func TestSendPushNotification(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping TestSendPushNotification test in short mode")
+	}
+
+	th := Setup(t).InitBasic()
+	defer th.TearDown()
+	api := th.SetupPluginAPI()
+
+	// Create 3 users, each having 2 sessions.
+	type userSession struct {
+		user    *model.User
+		session *model.Session
+	}
+	var userSessions []userSession
+	for i := 0; i < 3; i++ {
+		u := th.CreateUser()
+		sess, err := th.App.CreateSession(&model.Session{
+			UserId:    u.Id,
+			DeviceId:  "deviceID" + u.Id,
+			ExpiresAt: model.GetMillis() + 100000,
+		})
+		require.Nil(t, err)
+		// We don't need to track the 2nd session.
+		_, err = th.App.CreateSession(&model.Session{
+			UserId:    u.Id,
+			DeviceId:  "deviceID" + u.Id,
+			ExpiresAt: model.GetMillis() + 100000,
+		})
+		require.Nil(t, err)
+		_, err = th.App.AddTeamMember(th.Context, th.BasicTeam.Id, u.Id)
+		require.Nil(t, err)
+		th.AddUserToChannel(u, th.BasicChannel)
+		userSessions = append(userSessions, userSession{
+			user:    u,
+			session: sess,
+		})
+	}
+
+	handler := &testPushNotificationHandler{
+		t:        t,
+		behavior: "simple",
+	}
+	pushServer := httptest.NewServer(
+		http.HandlerFunc(handler.handleReq),
+	)
+	defer pushServer.Close()
+
+	th.App.UpdateConfig(func(cfg *model.Config) {
+		*cfg.EmailSettings.PushNotificationContents = model.FullNotification
+		*cfg.EmailSettings.PushNotificationServer = pushServer.URL
+	})
+
+	var wg sync.WaitGroup
+	for _, data := range userSessions {
+		wg.Add(1)
+		go func(user model.User) {
+			defer wg.Done()
+			post := th.CreatePost(th.BasicChannel)
+			post.Message = "started a conversation"
+			notification := &model.PluginPushNotification{
+				Post:    post,
+				Channel: th.BasicChannel,
+				UserID:  user.Id,
+			}
+			appErr := api.SendPluginPushNotification(notification)
+			require.NoError(t, appErr)
+		}(*data.user)
+	}
+	wg.Wait()
+
+	// Hack to let the worker goroutines complete.
+	time.Sleep(1 * time.Second)
+	// Server side verification.
+	var numMessages int
+	for _, n := range handler.notifications() {
+		switch n.Type {
+		case model.PushTypeMessage:
+			numMessages++
+			assert.Equal(t, th.BasicChannel.Id, n.ChannelId)
+			assert.Equal(t, fmt.Sprintf("@%s: started a conversation", th.BasicUser.GetDisplayName(model.ShowUsername)), n.Message)
+		default:
+			assert.Fail(t, "should not receive any other push notification types")
+		}
+	}
+	assert.Equal(t, 6, numMessages)
+}