Don't trigger beforeSave when logging in with a provider

spec/ParseUser.spec.js

@@ -1026,6 +1026,32 @@ describe('Parse.User testing', () => {
     });
   });
 
+  it("login with provider should not call beforeSave trigger", (done) => {
+    var provider = getMockFacebookProvider();
+    Parse.User._registerAuthenticationProvider(provider);
+    Parse.User._logInWith("facebook", {
+      success: function(model) {
+        Parse.User.logOut();
+
+        Parse.Cloud.beforeSave(Parse.User, function(req, res) {
+          res.error("Before save shouldn't be called on login");
+        });
+
+        Parse.User._logInWith("facebook", {
+          success: function(innerModel) {
+            Parse.Cloud._removeHook('Triggers', 'beforeSave', Parse.User.className);
+            done();
+          },
+          error: function(model, error) {
+            ok(undefined, error);
+            Parse.Cloud._removeHook('Triggers', 'beforeSave', Parse.User.className);
+            done();
+          }
+        });
+      }
+    });
+  });
+
   it("link with provider", (done) => {
     var provider = getMockFacebookProvider();
     Parse.User._registerAuthenticationProvider(provider);

src/RestWrite.js

@@ -67,12 +67,12 @@ RestWrite.prototype.execute = function() {
     return this.handleInstallation();
   }).then(() => {
     return this.handleSession();
+  }).then(() => {
+    return this.validateAuthData();
   }).then(() => {
     return this.runBeforeTrigger();
   }).then(() => {
     return this.setRequiredFieldsIfNeeded();
-  }).then(() => {
-    return this.validateAuthData();
   }).then(() => {
     return this.transformUser();
   }).then(() => {
@@ -134,6 +134,10 @@ RestWrite.prototype.validateSchema = function() {
 // Runs any beforeSave triggers against this operation.
 // Any change leads to our data being mutated.
 RestWrite.prototype.runBeforeTrigger = function() {
+  if (this.response) {
+    return;
+  }
+
   // Avoid doing any setup for triggers if there is no 'beforeSave' trigger for this class.
   if (!triggers.triggerExists(this.className, triggers.Types.beforeSave, this.config.applicationId)) {
     return Promise.resolve();