Token-based authentication in Cypress - Test Execution Trace

Test Overview

This test logs in using a token-based authentication and verifies that the user dashboard loads successfully.

Test Code - Cypress

Cypress

describe('Token-based authentication test', () => {
  it('logs in with token and verifies dashboard', () => {
    // Set token in local storage
    cy.visit('/');
    cy.window().then(win => {
      win.localStorage.setItem('authToken', 'fake-jwt-token-123');
    });
    // Reload to apply token
    cy.reload();
    // Navigate to dashboard
    cy.visit('/dashboard');
    // Check if dashboard heading is visible
    cy.get('h1').should('contain.text', 'User Dashboard');
  });
});

Execution Trace - 5 Steps

Step	Action	System State	Assertion	Result
1	Visit the home page	Browser opens at '/' with empty local storage	—	PASS
2	Set 'authToken' in local storage with a fake JWT token	Local storage now contains 'authToken' with value 'fake-jwt-token-123'	—	PASS
3	Reload the page to apply the token	Page reloads, token is present in local storage	—	PASS
4	Navigate to '/dashboard' page	Browser navigates to '/dashboard' page	—	PASS
5	Find the heading element and check its text contains 'User Dashboard'	Dashboard page is loaded with heading visible	Verify heading text contains 'User Dashboard'	PASS

Failure Scenario

Failing Condition: The token is missing or invalid, so the dashboard page does not load correctly.

Execution Trace Quiz - 3 Questions

What is the purpose of setting 'authToken' in local storage in this test?

A To clear the browser cache before testing

B To store user preferences for the dashboard

C To simulate a logged-in user by providing the authentication token

D To test if local storage is writable

Key Result

Setting the authentication token directly in local storage is a fast way to simulate a logged-in user in tests without going through the login UI.

Practice

1. What is the main advantage of using token-based authentication in Cypress tests?

easy

A. It disables all API requests during testing.

B. It requires manual input of username and password every time.

C. It automatically generates UI elements for login.

D. It allows tests to log in quickly without interacting with the UI.

Solution

1. Step 1: Understand token-based authentication purpose

   Token-based authentication lets tests bypass UI login by using tokens directly.

2. Step 2: Compare options

   Only It allows tests to log in quickly without interacting with the UI. correctly states the advantage of faster login without UI interaction.

3. Final Answer:

   It allows tests to log in quickly without interacting with the UI. -> Option D

4. Quick Check:

   Token-based authentication = Fast login without UI [OK]

Hint: Token-based auth skips UI login for faster tests [OK]

Common Mistakes:

• Thinking token auth requires UI interaction
• Confusing token auth with disabling APIs
• Assuming token auth auto-generates UI

2. Which Cypress command is commonly used to request an authentication token from an API?

easy

A. cy.visit()

B. cy.get()

C. cy.request()

D. cy.contains()

Solution

1. Step 1: Identify command for API calls

   cy.request() is used to make HTTP requests to APIs, including login endpoints.

2. Step 2: Eliminate other commands

   cy.visit() loads pages, cy.get() selects DOM elements, cy.contains() finds text; none request tokens.

3. Final Answer:

   cy.request() -> Option C

4. Quick Check:

   API token request = cy.request() [OK]

Hint: Use cy.request() to call APIs and get tokens [OK]

Common Mistakes:

• Using cy.visit() to get tokens
• Confusing cy.get() with API calls
• Trying cy.contains() for authentication

3. Given the code below, what will be the value of token after the test runs?

let token = '';
cy.request('POST', '/api/login', { username: 'user', password: 'pass' })
  .then((response) => {
    token = response.body.token;
  });

medium

A. An empty string because token is declared outside the callback

B. The token string returned by the API in response.body.token

C. Undefined because response.body.token does not exist

D. The entire response object

Solution

1. Step 1: Understand asynchronous assignment

   The token variable is assigned inside the .then() callback after the API response arrives.

2. Step 2: Confirm token value after request

   response.body.token contains the token string from the API, so token gets that value.

3. Final Answer:

   The token string returned by the API in response.body.token -> Option B

4. Quick Check:

   token = response.body.token string [OK]

Hint: Token is set inside .then() from response.body.token [OK]

Common Mistakes:

• Assuming token stays empty due to async
• Thinking token is undefined without checking API
• Confusing token with full response object

4. Identify the error in this Cypress test snippet for token-based login:

cy.request('POST', '/api/login', { username: 'user', password: 'pass' })
  .then((response) => {
    cy.setCookie('authToken', response.token);
  });

medium

A. response.token should be response.body.token to access the token

B. cy.setCookie is not a valid Cypress command

C. The request method should be GET, not POST

D. Cookies cannot store authentication tokens

Solution

1. Step 1: Check response object structure

   The token is usually inside response.body.token, not directly response.token.

2. Step 2: Validate cy.setCookie usage

   cy.setCookie is a valid command to set cookies in Cypress.

3. Final Answer:

   response.token should be response.body.token to access the token -> Option A

4. Quick Check:

   Access token via response.body.token [OK]

Hint: Use response.body.token, not response.token [OK]

Common Mistakes:

• Using response.token instead of response.body.token
• Thinking cy.setCookie is invalid
• Changing POST to GET incorrectly

5. You want to write a Cypress test that logs in using token-based authentication and then visits a protected page. Which sequence correctly achieves this?

A) cy.request('POST', '/api/login', {username: 'user', password: 'pass'}).then(res => {
  cy.setCookie('token', res.token);
});
cy.visit('/protected');

B) cy.visit('/protected');
cy.request('POST', '/api/login', {username: 'user', password: 'pass'}).then(res => {
  cy.setCookie('token', res.body.token);
});

C) cy.request('POST', '/api/login', {username: 'user', password: 'pass'}).then(res => {
  cy.setCookie('token', res.body.token);
  cy.visit('/protected');
});

D) cy.setCookie('token', 'dummy');
cy.visit('/protected');

hard

A. Set dummy token cookie, then visit protected page

B. Visit protected page first, then request token and set cookie

C. Request token, set cookie, then visit protected page outside .then()

D. Request token, set cookie, then visit protected page inside .then() callback

Solution

1. Step 1: Understand asynchronous flow

   Token must be set before visiting the protected page, so visit must happen after setting cookie inside .then().

2. Step 2: Analyze options

   Request token, set cookie, then visit protected page inside .then() callback sets cookie and visits page inside .then(), ensuring correct order and token availability.

3. Final Answer:

   Request token, set cookie, then visit protected page inside .then() callback -> Option A

4. Quick Check:

   Set token cookie before visiting page inside .then() [OK]

Hint: Visit protected page only after setting token cookie inside .then() [OK]

Common Mistakes:

• Visiting page before setting token cookie
• Setting cookie outside async callback
• Using dummy tokens without real login