Adds index on _Role name property

In order to avoid having different _Role objects with the same name, adding an index on the name property of _Role is necessary.

Fixes #3579

Author: natanrolnik

spec/ParseRole.spec.js

@@ -192,6 +192,24 @@ describe('Parse Role testing', () => {
     });
   });
 
+  it("Different _Role objects cannot have the same name.", (done) => {
+    const roleName = "MyRole";
+    let aUser;
+    createTestUser().then((user) => {
+      aUser = user;
+      return createRole(roleName, null, aUser);
+    }).then((firstRole) => {
+      expect(firstRole.getName()).toEqual(roleName);
+      return createRole(roleName, null, aUser);
+    }).then(() => {
+      fail("_Role cannot have the same name as another role");
+      done();
+    }, (error) => {
+      expect(error.code).toEqual(137);
+      done();
+    });
+  });
+
   it("Should properly resolve roles", (done) => {
     const admin = new Parse.Role("Admin", new Parse.ACL());
     const moderator = new Parse.Role("Moderator", new Parse.ACL());

src/Controllers/DatabaseController.js

@@ -909,9 +909,12 @@ DatabaseController.prototype.addPointerPermissions = function(schema, className,
 // have a Parse app without it having a _User collection.
 DatabaseController.prototype.performInitialization = function() {
   const requiredUserFields = { fields: { ...SchemaController.defaultColumns._Default, ...SchemaController.defaultColumns._User } };
+  const requiredRoleFields = { fields: { ...SchemaController.defaultColumns._Default, ...SchemaController.defaultColumns._Role } };
 
   const userClassPromise = this.loadSchema()
     .then(schema => schema.enforceClassExists('_User'))
+  const roleClassPromise = this.loadSchema()
+    .then(schema => schema.enforceClassExists('_Role'))
 
   const usernameUniqueness = userClassPromise
     .then(() => this.adapter.ensureUniqueness('_User', requiredUserFields, ['username']))
@@ -927,9 +930,16 @@ DatabaseController.prototype.performInitialization = function() {
       return Promise.reject(error);
     });
 
+  const roleUniqueness = roleClassPromise
+    .then(() => this.adapter.ensureUniqueness('_Role', requiredRoleFields, ['name']))
+    .catch(error => {
+      logger.warn('Unable to ensure uniqueness for role name: ', error);
+      return Promise.reject(error);
+    });
+
   // Create tables for volatile classes
   const adapterInit = this.adapter.performInitialization({ VolatileClassesSchemas: SchemaController.VolatileClassesSchemas });
-  return Promise.all([usernameUniqueness, emailUniqueness, adapterInit]);
+  return Promise.all([usernameUniqueness, emailUniqueness, roleUniqueness, adapterInit]);
 }
 
 function joinTableName(className, key) {