MSAL Authentication Challenge for Internal Microsoft Application Testing

[vrushti-mody]

We are developing Cypress E2E tests for an internal Microsoft application (Azure Aurora Fairbanks Frontend) that uses MSAL (Microsoft Authentication Library) for authentication. Our application has unique authentication requirements that make standard Cypress authentication approaches challenging users must authenticate through Microsoft's Azure AD, belong to specific security groups managed in Microsoft's Core Identity system, and have role-based access (ReadOnly, ReadWrite, Admin) that is dynamically fetched from backend APIs after authentication. The application immediately redirects to login.microsoftonline.com upon visiting localhost:3000, preventing any test execution. Additionally, the app implements workspace-based permissions where users can have different access levels in different workspaces. Since this is an internal Microsoft application, we cannot use typical OAuth testing approaches like creating test users with disabled MFA or using the Resource Owner Password Flow with client secrets, as these would require special permissions and security exceptions within Microsoft's corporate environment. We need guidance on the best approach to mock MSAL authentication in Cypress tests while maintaining the ability to test different user roles and permissions without actually authenticating against Microsoft's identity services. The ideal solution would allow us to bypass the initial MSAL redirect, inject mock user sessions with appropriate tokens and claims (including security group memberships), and intercept backend API calls that validate roles, all while keeping our test environment isolated from production authentication systems.

[loguinha]

Hey! this is a classic and challenging problem, especially in enterprise environments with strict security policies like Microsoft's. Programmatic login is often a dead-end, so your instinct to mock the authentication layer is the correct one.

The most robust solution is to completely mock the MSAL library at the test level. This approach bypasses the redirect entirely and gives you full control over the user's session, roles, and permissions without ever needing to touch the real identity services.

Here’s a high-level breakdown of how you can implement this:

Strategy: A Custom cy.login() Command

The best way to manage this is by creating a custom command, like cy.login('Admin'), that handles the entire mock setup. This command would perform three key actions:

1. Seed the Session in localStorage
Before visiting the page, your command should write mock MSAL account and token data directly into localStorage. Your application will read this on startup and believe a user is already authenticated.

2. Intercept API Calls for Roles
Use cy.intercept() to catch the request your app makes to its backend to fetch user roles (e.g., GET /api/user/permissions). In the intercept, you can return a mock response with whatever roles (ReadOnly, Admin, etc.) you need for that specific test.

3. Stub MSAL Before the App Loads (The Key Step)
This is the most critical part. Use the onBeforeLoad callback in cy.visit() to replace the real msal.PublicClientApplication object with a lightweight mock before your app's code executes. This mock will have do-nothing methods for any functions that would trigger a redirect.

Here is a simplified code example of what the core logic inside your cy.login() command would look like:
JavaScript:

// Inside your custom cy.login() command

// (Logic to set localStorage items goes here first)
// (Logic for cy.intercept() goes here)

cy.visit('/', {
  onBeforeLoad(win) {
    // Replace the real MSAL with a mock that does nothing
    win.msal = {
      PublicClientApplication: class {
        // Mock methods that your app calls
        async handleRedirectPromise() {
          return Promise.resolve(null); // Prevents redirect loops
        }
        getAllAccounts() {
          // Return the mock account you seeded in localStorage
          return [mockAccount]; 
        }
        loginRedirect() {
          // IMPORTANT: Do nothing here to prevent the redirect.
          console.log('MSAL Mock: Blocked loginRedirect()');
        }
        // Mock other methods like acquireTokenSilent, logoutRedirect etc.
      },
    };
  },
});

With this setup, your tests become clean and declarative, focusing only on the application's behavior:
JavaScript

it('should allow an Admin to access the settings page', () => {
  cy.login('Admin'); // Your command handles all the magic
  cy.get('[data-cy="settings-link"]').click();
  cy.url().should('include', '/settings');
});

it('should prevent a ReadOnly user from seeing the settings page', () => {
  cy.login('ReadOnly');
  cy.get('[data-cy="settings-link"]').should('not.exist');
});

This approach completely isolates your test environment and gives you precise control to simulate any user role or permission set you need. Hope this gives you a clear path forward!

We are developing Cypress E2E tests for an internal Microsoft application (Azure Aurora Fairbanks Frontend) that uses MSAL (Microsoft Authentication Library) for authentication. Our application has unique authentication requirements that make standard Cypress authentication approaches challenging users must authenticate through Microsoft's Azure AD, belong to specific security groups managed in Microsoft's Core Identity system, and have role-based access (ReadOnly, ReadWrite, Admin) that is dynamically fetched from backend APIs after authentication. The application immediately redirects to login.microsoftonline.com upon visiting localhost:3000, preventing any test execution. Additionally, the app implements workspace-based permissions where users can have different access levels in different workspaces. Since this is an internal Microsoft application, we cannot use typical OAuth testing approaches like creating test users with disabled MFA or using the Resource Owner Password Flow with client secrets, as these would require special permissions and security exceptions within Microsoft's corporate environment. We need guidance on the best approach to mock MSAL authentication in Cypress tests while maintaining the ability to test different user roles and permissions without actually authenticating against Microsoft's identity services. The ideal solution would allow us to bypass the initial MSAL redirect, inject mock user sessions with appropriate tokens and claims (including security group memberships), and intercept backend API calls that validate roles, all while keeping our test environment isolated from production authentication systems.