Dynamic test data generation in Cypress - Build an Automation Script

Automate user registration with dynamic test data

Preconditions (2)

Step 1: Open the registration page at '/register'

Step 2: Generate a random valid email address

Step 3: Generate a random valid username

Step 4: Enter the generated email in the email input field with id 'email'

Step 5: Enter the generated username in the username input field with id 'username'

Step 6: Enter 'Password123!' in the password input field with id 'password'

Step 7: Enter 'Password123!' in the confirm password input field with id 'confirmPassword'

Step 8: Click the submit button with id 'submitBtn'

Step 9: Wait for the success message with class 'success-message' to appear

✅ Expected Result: The success message 'Registration successful' is displayed confirming the user was registered with the dynamic data

Automation Requirements - Cypress

Assertions Needed:

Verify the success message text is exactly 'Registration successful'

Verify the URL changes to '/welcome' after registration

Best Practices:

Use Cypress commands consistently (cy.visit, cy.get, cy.type, cy.click)

Generate dynamic test data inside the test to avoid hardcoded values

Use explicit assertions with .should() for validation

Use semantic and stable selectors (id, class) for locating elements

Avoid using fixed waits; rely on Cypress automatic waits

Automated Solution

Cypress

describe('User Registration with Dynamic Data', () => {
  function generateRandomEmail() {
    const randomPart = Math.random().toString(36).substring(2, 10);
    return `user_${randomPart}@testmail.com`;
  }

  function generateRandomUsername() {
    const randomPart = Math.random().toString(36).substring(2, 8);
    return `user_${randomPart}`;
  }

  it('should register a new user with dynamic data', () => {
    const email = generateRandomEmail();
    const username = generateRandomUsername();
    const password = 'Password123!';

    cy.visit('/register');

    cy.get('#email').type(email);
    cy.get('#username').type(username);
    cy.get('#password').type(password);
    cy.get('#confirmPassword').type(password);

    cy.get('#submitBtn').click();

    cy.get('.success-message')
      .should('be.visible')
      .and('have.text', 'Registration successful');

    cy.url().should('include', '/welcome');
  });
});

This Cypress test automates the user registration process using dynamic test data.

First, two helper functions generate a random email and username to avoid hardcoded values and ensure uniqueness.

The test visits the registration page, fills in the form fields with the generated data and a fixed password, then submits the form.

Assertions check that the success message appears with the exact text and that the URL changes to '/welcome', confirming successful registration.

Selectors use stable IDs and classes for reliability. Cypress commands handle waiting automatically, so no fixed delays are used.

Common Mistakes - 3 Pitfalls

Hardcoding email and username instead of generating dynamically

Using cy.wait() with fixed time instead of relying on automatic waits

Using brittle selectors like XPath or overly complex CSS selectors

Bonus Challenge

Now add data-driven testing with 3 different sets of dynamic user data to register multiple users in one test suite.

Show Hint

Practice

1. What is the main benefit of using dynamic test data generation in Cypress tests?

easy

A. It creates unique data for each test run to avoid conflicts.

B. It makes tests run slower by adding delays.

C. It hardcodes values to ensure consistency.

D. It disables assertions to speed up tests.

Solution

1. Step 1: Understand dynamic data purpose

   Dynamic test data generation creates fresh data each time to prevent clashes with existing data.

2. Step 2: Compare options

   Only It creates unique data for each test run to avoid conflicts. describes this benefit correctly; others describe incorrect or unrelated effects.

3. Final Answer:

   It creates unique data for each test run to avoid conflicts. -> Option A

4. Quick Check:

   Dynamic data = unique per run [OK]

Hint: Dynamic data means fresh unique values each test run [OK]

Common Mistakes:

• Thinking dynamic data slows tests
• Confusing dynamic with hardcoded data
• Believing dynamic data disables assertions

2. Which of the following is the correct way to generate a random email in Cypress using JavaScript template literals?

easy

A. const email = user${Math.random()}@test.com;

B. const email = 'user' + Math.random() + '@test.com';

C. const email = `user+Math.random()@test.com`;

D. const email = `user${Math.random()}@test.com`;

Solution

1. Step 1: Identify correct template literal syntax

   Template literals use backticks and ${} to embed expressions, so `user${Math.random()}@test.com` is correct.

2. Step 2: Check other options

   const email = 'user' + Math.random() + '@test.com'; uses string concatenation, which works but is not template literals. const email = user${Math.random()}@test.com; misses backticks. const email = `user+Math.random()@test.com`; treats Math.random() as string literal.

3. Final Answer:

   const email = `user${Math.random()}@test.com`; -> Option D

4. Quick Check:

   Template literals use backticks and ${} [OK]

Hint: Template literals use backticks and ${expression} [OK]

Common Mistakes:

• Using quotes instead of backticks for template literals
• Forgetting ${} around expressions
• Treating expressions as plain text

3. Given the Cypress code snippet:

const randomId = Math.floor(Math.random() * 1000);
cy.get('#user-input').type(`user${randomId}`);
cy.get('#submit-btn').click();
cy.get('#result').should('contain', `user${randomId}`);

What will the assertion check?

medium

A. That the element with id 'result' contains a random number only.

B. That the element with id 'result' contains the text 'user' only.

C. That the element with id 'result' contains the exact text 'user' plus the random number generated.

D. That the element with id 'result' contains the string 'randomId'.

Solution

1. Step 1: Understand variable usage in template literals

   The variable randomId is generated once and used in the string `user${randomId}` for typing and assertion.

2. Step 2: Analyze assertion

   The assertion checks if '#result' contains the exact string 'user' concatenated with the random number stored in randomId.

3. Final Answer:

   That the element with id 'result' contains the exact text 'user' plus the random number generated. -> Option C

4. Quick Check:

   Assertion checks full dynamic string [OK]

Hint: Assertions check exact dynamic string used in test [OK]

Common Mistakes:

• Assuming assertion checks only 'user' text
• Thinking random number is checked alone
• Confusing variable name with string literal

4. Identify the error in this Cypress test code that tries to generate a random username:

const username = 'user' + Math.random;
cy.get('#username').type(username);
cy.get('#submit').click();

medium

A. The username variable should be declared inside the test only.

B. Math.random is missing parentheses, so it is a function reference, not a number.

C. The selector '#username' is invalid and should be '.username'.

D. The click command is missing parentheses.

Solution

1. Step 1: Check Math.random usage

   Math.random is a function and must be called with parentheses to get a number. Without (), username becomes 'user' plus function reference string.

2. Step 2: Verify other parts

   Selectors and click command syntax are correct. The main error is missing parentheses on Math.random.

3. Final Answer:

   Math.random is missing parentheses, so it is a function reference, not a number. -> Option B

4. Quick Check:

   Call Math.random() with () to get number [OK]

Hint: Always call Math.random() with parentheses [OK]

Common Mistakes:

• Forgetting parentheses on Math.random
• Misreading selector syntax
• Thinking click needs extra parentheses

5. You want to generate a dynamic user object with unique email and username for each Cypress test run. Which approach correctly creates this object and uses it in a test?

const user = {
  username: `user${Math.floor(Math.random() * 10000)}`,
  email: `email${Math.floor(Math.random() * 10000)}@test.com`
};

cy.visit('/signup');
cy.get('#username').type(user.username);
cy.get('#email').type(user.email);
cy.get('#submit').click();
cy.get('#welcome').should('contain', user.username);

hard

A. This approach correctly generates unique user data and uses it in the test assertions.

B. This approach fails because Math.random() should not be used for test data.

C. This approach is incorrect because user object must be inside cy.then() callback.

D. This approach is wrong because template literals cannot be used inside objects.

Solution

1. Step 1: Analyze user object creation

   The user object uses template literals with Math.floor(Math.random() * 10000) to create unique username and email strings before the test runs.

2. Step 2: Check usage in Cypress commands

   The test types the dynamic username and email into inputs, clicks submit, and asserts the welcome message contains the username, which is valid and correct.

3. Final Answer:

   This approach correctly generates unique user data and uses it in the test assertions. -> Option A

4. Quick Check:

   Dynamic object with random values used correctly [OK]

Hint: Create dynamic objects before test, then use in commands [OK]

Common Mistakes:

• Thinking Math.random() is disallowed for test data
• Believing object must be inside cy.then() unnecessarily
• Misunderstanding template literal usage inside objects