Auth module refactoring in order to be reusable (#4940)

* Auth module refactoring in order to be reusable

* Ensure cache controller is properly forwarded from helpers

* Nits

spec/Auth.spec.js

@@ -1,6 +1,6 @@
 describe('Auth', () => {
-  const Auth = require('../lib/Auth.js').Auth;
-
+  const { Auth, getAuthForSessionToken } = require('../lib/Auth.js');
+  const Config = require('../lib/Config');
   describe('getUserRoles', () => {
     let auth;
     let config;
@@ -90,4 +90,33 @@ describe('Auth', () => {
     });
 
   });
+
+  it('should load auth without a config', async () => {
+    const user = new Parse.User();
+    await user.signUp({
+      username: 'hello',
+      password: 'password'
+    });
+    expect(user.getSessionToken()).not.toBeUndefined();
+    const userAuth = await getAuthForSessionToken({
+      sessionToken: user.getSessionToken()
+    });
+    expect(userAuth.user instanceof Parse.User).toBe(true);
+    expect(userAuth.user.id).toBe(user.id);
+  });
+
+  it('should load auth with a config', async () => {
+    const user = new Parse.User();
+    await user.signUp({
+      username: 'hello',
+      password: 'password'
+    });
+    expect(user.getSessionToken()).not.toBeUndefined();
+    const userAuth = await getAuthForSessionToken({
+      sessionToken: user.getSessionToken(),
+      config: Config.get('test'),
+    });
+    expect(userAuth.user instanceof Parse.User).toBe(true);
+    expect(userAuth.user.id).toBe(user.id);
+  });
 });