MM-15889 Add unit tests for CSRF checks (#11058)

* MM-15889 Add unit tests for CSRF checks

* Moved CSRF token test to login tests

* Remove empty test

* Remove debug messages

api4/oauth.go

@@ -515,7 +515,6 @@ func completeOAuth(c *Context, w http.ResponseWriter, r *http.Request) {
 	if action == model.OAUTH_ACTION_EMAIL_TO_SSO {
 		redirectUrl = c.GetSiteURLHeader() + "/login?extra=signin_change"
 	} else if action == model.OAUTH_ACTION_SSO_TO_EMAIL {
-
 		redirectUrl = app.GetProtocol(r) + "://" + r.Host + "/claim?email=" + url.QueryEscape(props["email"])
 	} else {
 		session, err := c.App.DoLogin(w, r, user, "")
@@ -528,6 +527,8 @@ func completeOAuth(c *Context, w http.ResponseWriter, r *http.Request) {
 			return
 		}
 
+		c.App.AttachSessionCookies(w, r, session)
+
 		c.App.Session = *session
 
 		if _, ok := props["redirect_to"]; ok {