users service: add sessions (#17744)

* users: add cache to service

* reflect review comments

app/session_test.go

@@ -8,7 +8,6 @@ import (
 	"fmt"
 	"os"
 	"testing"
-	"time"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -16,43 +15,6 @@ import (
 	"github.com/mattermost/mattermost-server/v5/model"
 )
 
-func TestCache(t *testing.T) {
-	th := Setup(t)
-	defer th.TearDown()
-
-	session := &model.Session{
-		Id:     model.NewId(),
-		Token:  model.NewId(),
-		UserId: model.NewId(),
-	}
-
-	session2 := &model.Session{
-		Id:     model.NewId(),
-		Token:  model.NewId(),
-		UserId: model.NewId(),
-	}
-
-	th.App.Srv().sessionCache.SetWithExpiry(session.Token, session, 5*time.Minute)
-	th.App.Srv().sessionCache.SetWithExpiry(session2.Token, session2, 5*time.Minute)
-
-	keys, err := th.App.Srv().sessionCache.Keys()
-	require.NoError(t, err)
-	require.NotEmpty(t, keys)
-
-	th.App.ClearSessionCacheForUser(session.UserId)
-
-	rkeys, err := th.App.Srv().sessionCache.Keys()
-	require.NoError(t, err)
-	require.Lenf(t, rkeys, len(keys)-1, "should have one less: %d - %d != 1", len(keys), len(rkeys))
-	require.NotEmpty(t, rkeys)
-
-	th.App.ClearSessionCacheForAllUsers()
-
-	rkeys, err = th.App.Srv().sessionCache.Keys()
-	require.NoError(t, err)
-	require.Empty(t, rkeys)
-}
-
 func TestGetSessionIdleTimeoutInMinutes(t *testing.T) {
 	th := Setup(t)
 	defer th.TearDown()
@@ -355,8 +317,7 @@ func TestApp_ExtendExpiryIfNeeded(t *testing.T) {
 			require.False(t, session.IsExpired())
 
 			// check cache was updated
-			var cachedSession *model.Session
-			errGet := th.App.Srv().sessionCache.Get(session.Token, &cachedSession)
+			cachedSession, errGet := th.App.srv.userService.GetSession(session.Token)
 			require.NoError(t, errGet)
 			require.Equal(t, session.ExpiresAt, cachedSession.ExpiresAt)