In today’s highly competitive landscape of software testing, efficient handling of network requests is the key to ensuring seamless functionality of web applications. The modern end-to-end testing framework Cypress provides strong features for intercepting and testing network requests, so it’s a game-changer for test automation.

This blog delves into the world of network interception with Cypress. From the basics of API request handling to advanced stubbing techniques and validation of responses, this guide runs through everything. It illustrates how Cypress equips testers with the ability to simulate edge cases, debug complex interactions, and easily obtain higher test coverage. By the end of this post, you’ll have a comprehensive understanding of how to incorporate network interception into your Cypress test automation strategy, enhancing both test reliability and efficiency.

This blog is tailored for testers and developers looking to elevate their automation skills, offering step-by-step instructions, practical examples, and insights into best practices for network testing.

What is Network Request Interception?

Network request interception in the context of automation testing refers to the process of monitoring, modifying, or completely stubbing HTTP requests and responses between the client and server during a test session. This functionality is pivotal for testing scenarios that depend on APIs or web services, ensuring that the application handles all possible conditions like successful responses, server errors, and delayed responses.

For instance:

• Intercepting an API call for fetching user data and simulating a response with dummy data can validate how the application handles different scenarios without reliance on backend availability.
• Testing an edge case where the server sends a 500 error allows validation of fallback mechanisms or error messages in the UI.

Why is Network Interception Crucial in Automation Testing?

1. Isolate Application Behaviour: Test frontend logic without relying on live backend servers, which might be unstable or unavailable.
2. Simulate Edge Cases: Easily simulate scenarios like slow network responses, server errors, or unexpected payloads.
3. Improve Test Reliability: Reduce flakiness by controlling external dependencies, making tests more stable and repeatable.
4. Validate API Contracts: Ensure the application sends the correct requests and processes responses as expected.
5. Debugging Made Easy: Intercept requests and responses to gain visibility into what the application is communicating with the server.

Benefits of Using Cypress for API Interception

Cypress simplifies network interception with its powerful cy.intercept command, offering several advantages over traditional testing tools:

Ease of Use: Cypress provides a declarative and readable syntax for intercepting and modifying network requests.

cy.intercept('GET', '/api/users', { fixture: 'users.json' }).as('getUsers');
cy.visit('/users');
cy.wait('@getUsers');

Example: In the code above, any GET request to /api/users is intercepted, and Cypress serves a predefined JSON response from the users.json fixture file.

Real-Time Debugging: Cypress’s built-in test runner shows intercepted requests and their details in real time, allowing for quick validation and troubleshooting.

No Middleware Required: Unlike some tools that require a proxy server or middleware, Cypress integrates natively, saving setup time.

Simulating Complex Scenarios: With cy.intercept, you can mock API responses dynamically to test complex workflows like pagination or authentication.

Example – Simulating Pagination:

cy.intercept('GET', '/api/products?page=1', { fixture: 'page1.json' }).as('page1');
cy.intercept('GET', '/api/products?page=2', { fixture: 'page2.json' }).as('page2');

cy.visit('/products');
cy.wait('@page1'); // Wait for the first page data to load

cy.get('.next-page').click(); // Navigate to the next page
cy.wait('@page2'); // Wait for the second page data to load

Comprehensive Assertions: Cypress allows assertions on requests, payloads, headers, and responses.

Example – Validating Request Payload:

cy.intercept('POST', '/api/login', (req) => {
  expect(req.body).to.have.property('username', 'testuser');
}).as('loginRequest');

cy.get('#loginButton').click();
cy.wait('@loginRequest');

Simplified Test Maintenance: With features like fixtures and aliases, you can organise test data and intercepts effectively for reuse across multiple tests.

By using network request interception with Cypress, you gain full control over your application’s external dependencies, enabling robust and comprehensive automation tests that validate both UI and API layers. It’s an essential skill for modern test automation practitioners.

The Basics of cy.intercept in Cypress

Introduction to cy.intercept command

cy.intercept is a Cypress command that allows you to intercept and modify HTTP requests and responses. It replaced the now-deprecated cy.route command in Cypress 6.0, offering enhanced functionality and better control over network traffic during tests.

This powerful feature can:

1. Monitor outgoing and incoming HTTP requests.
2. Stub and mock responses.
3. Validate payloads, headers, and response structures.
4. Simulate edge cases such as timeouts, server errors, or invalid data.

Key Differences Between cy.route and cy.intercept

Feature	cy.route (deprecated)	cy.intercept
Protocol Support	HTTP only	HTTP, HTTPS, and WebSockets
Dynamic Requests	Limited	Full support (regex, wildcards, etc.)
Response Modification	Basic stubbing	Flexible with callback functions
Logging and Debugging	Minimal details	Rich, detailed logs in the Cypress Test Runner

cy.intercept provides unmatched flexibility by allowing detailed request matching, response manipulation, and advanced validations.

Syntax Overview basic usage

The cy.intercept command can accept various arguments depending on the complexity of your requirements

Basic Syntax

Parameter	Description	Example
method	HTTP method to intercept (e.g., GET, POST, PUT, etc.)	‘GET’
url	Endpoint URL to intercept	‘/api/users’
response	Mocked or stubbed response	{ fixture: ‘users.json’ }

Examples of cy.intercept Usage

Intercepting a GET Request Monitor and validate a GET request to an API endpoint:

cy.intercept('GET', '/api/users').as('getUsers'); // Intercept the GET request to '/api/users' and assign an alias
cy.visit('/users'); // Navigate to the '/users' page
cy.wait('@getUsers').then((interception) => {
  // Wait for the intercepted GET request and access the interception object
  expect(interception.response.statusCode).to.eq(200); // Verify that the response status code is 200
  expect(interception.response.body).to.have.length(5); // Verify that the response body has exactly 5 items
});

Explanation:

• Intercept requests to /api/users.
• Assign an alias @getUsers for easier reference.
• Validate the status code and response body.

Stubbing a Response Mock a server response with predefined data using a JSON fixture:

cy.intercept('GET', '/api/products', { fixture: 'products.json' }).as('getProducts');
cy.visit('/products');
cy.wait('@getProducts');

Explanation:

• Any GET request to /api/products will receive data from the products.json file.

Dynamic Response Modification Modify the response payload dynamically based on the test scenario:

cy.intercept('POST', '/api/login', (req) => {
  req.reply((res) => {
    res.body.success = false; // Modify the response to indicate failure
    res.body.message = 'Invalid credentials'; // Add a custom error message
  });
}).as('loginAttempt');

cy.get('#loginButton').click(); // Simulate a click on the login button
cy.wait('@loginAttempt'); // Wait for the intercepted POST request

Explanation:

• Intercept a POST request and override the response body dynamically to simulate a login failure.

Simulating a Server Error Test how the application handles a 500 server error:

cy.intercept('GET', '/api/orders', {
  statusCode: 500, // Simulate an Internal Server Error
  body: { error: 'Internal Server Error' }, // Custom error message in the response body
}).as('getOrders');

cy.visit('/orders'); // Navigate to the '/orders' page
cy.wait('@getOrders'); // Wait for the intercepted GET request

Explanation:

• Simulates a 500 error, allowing you to verify error-handling mechanisms in the application.

Validating Request Payload Ensure the correct data is being sent in a request payload:

cy.intercept('POST', '/api/submit', (req) => {
  expect(req.body).to.have.property('username', 'testuser'); // Assert the request body contains the 'username' property
  req.reply({ statusCode: 200 }); // Mock a successful response with status code 200
}).as('submitData');

cy.get('#submitButton').click(); // Simulate a click on the submit button
cy.wait('@submitData'); // Wait for the intercepted POST request to complete

Explanation:

• Intercepts a POST request to /api/submit and validates the payload’s structure and values.

Best Practices

1. Use Aliases: Assign aliases to intercepted requests for easy reference in cy.wait.
2. Organise Fixtures: Store reusable test data in the fixtures folder for consistent mock responses.
3. Test Edge Cases: Simulate various scenarios like delays, timeouts, and malformed responses.
4. Debugging: Use Cypress’s Test Runner to inspect intercepted requests and responses in real-time.

Intercepting GET, POST, PUT and DELETE Requests

Intercepting various HTTP request methods such as GET, POST, and PUT is essential for testing different API interactions within your web application. Cypress provides an intuitive and flexible way to manage these requests using the cy.intercept command. Let’s dive into detailed examples of how to intercept and stub these requests effectively.

Examples of intercepting various request methods

Intercepting a GET Request

Scenario: Testing how your application fetches a list of users from an API.

cy.intercept('GET', '/api/users', { fixture: 'users.json' }).as('getUsers'); // Mock the GET request to /api/users
cy.visit('/users'); // Navigate to the users page
cy.wait('@getUsers').then((interception) => {
  expect(interception.response.statusCode).to.eq(200); // Validate the status code is 200
  expect(interception.response.body).to.have.length(3); // Assert the response body contains 3 users
});

Explanation:

• Request: Intercepts any GET request to the /api/users endpoint.
• Stub Response: Uses the users.json fixture file to return predefined data.
• Validation: Checks the response’s status code and verifies that three users are returned.

Intercepting a POST Request

Scenario: Validating form submission that sends data to create a new user.

cy.intercept('POST', '/api/users', (req) => {
  // Validate the request payload
  expect(req.body).to.have.property('name', 'John Doe');
  
  // Stub the response with a success status and mock data
  req.reply({ 
    statusCode: 201, 
    body: { id: 101, name: 'John Doe' } 
  });
}).as('createUser');

// Simulate user input and submission
cy.get('#nameInput').type('John Doe'); // Enter 'John Doe' into the name input field
cy.get('#submitButton').click(); // Click the submit button

// Wait for the intercepted POST request and validate the response
cy.wait('@createUser').then((interception) => {
  expect(interception.response.statusCode).to.eq(201); // Assert response status code is 201
  expect(interception.response.body).to.have.property('id', 101); // Assert response contains the expected 'id'
});

Explanation:

• Request: Intercepts POST requests to /api/users.
• Validation: Checks if the payload contains the correct data (name: ‘John Doe’).
• Stub Response: Returns a mocked response with a status code of 201 and a newly created user object.
• Assertions: Ensures the request is sent with the correct data and the response contains the expected fields.

 Intercepting a PUT Request

Scenario: Testing the update functionality for an existing user’s data.

cy.intercept('PUT', '/api/users/101', (req) => {
  // Validate the request payload
  expect(req.body).to.have.property('email', 'john.doe@example.com');
  
  // Stub the response with updated user data
  req.reply({ 
    statusCode: 200, 
    body: { id: 101, name: 'John Doe', email: 'john.doe@example.com' } 
  });
}).as('updateUser');

// Simulate user input and submission
cy.get('#emailInput')
  .clear() // Clear the existing value in the email input field
  .type('john.doe@example.com'); // Enter the new email address
cy.get('#updateButton').click(); // Click the update button

// Wait for the intercepted PUT request and validate the response
cy.wait('@updateUser').then((interception) => {
  expect(interception.response.statusCode).to.eq(200); // Assert the response status is 200
  expect(interception.response.body.email).to.eq('john.doe@example.com'); // Validate the updated email in the response
});

Explanation:

• Request: Intercepts a PUT request to update the user with ID 101.
• Payload Validation: Ensures the updated email is present in the request payload.
• Stub Response: Returns a successful update response, reflecting the new email.
• Assertions: Checks that the response has the correct updated data.

Intercepting a DELETE Request

Scenario: Testing the deletion of a user from the system

cy.intercept('DELETE', '/api/users/101', {
  // Stub the response for the DELETE request
  statusCode: 200,
  body: { message: 'User deleted successfully' },
}).as('deleteUser');

// Simulate user clicking the delete button
cy.get('#deleteButton').click(); // Trigger the delete action

// Wait for the DELETE request and validate the response
cy.wait('@deleteUser').then((interception) => {
  expect(interception.response.statusCode).to.eq(200); // Assert the response status code is 200
  expect(interception.response.body.message).to.eq('User deleted successfully'); // Assert the response body message
});

Explanation:

• Intercepting DELETE: The command captures DELETE requests to the /api/users/101 endpoint.
• Stubbed Response: Returns a status code of 200 and a message indicating successful deletion.
• Validation: Confirms that the request was sent and verifies the response message.

Demonstrating network stubbing with dynamic responses

Dynamic Response Handling with Callbacks

Cypress allows you to dynamically control responses using callback functions. This is useful for simulating different scenarios based on the request data.

cy.intercept('GET', '/api/orders', (req) => {
  // Check if the authorization header is present in the request
  if (req.headers['authorization']) {
    // If the header is present, reply with a successful response
    req.reply({
      statusCode: 200,
      body: [{ id: 1, item: 'Laptop' }] // Mock data for the orders
    });
  } else {
    // If the authorization header is missing, reply with a 401 Unauthorized response
    req.reply({
      statusCode: 401,
      body: { error: 'Unauthorised' }
    });
  }
}).as('getOrders');

// Visit the orders page to trigger the GET request
cy.visit('/orders');

// Wait for the GET request to be completed
cy.wait('@getOrders');

Explanation:

• Conditional Response: The response depends on whether the request includes an authorization header.
• Multiple Scenarios: Simulates both successful (200) and unauthorised (401) responses within a single test.

Benefits of Dynamic Response Stubbing:

1. Enhanced Test Coverage: Simulates various real-world scenarios without changing the code or backend.
2. Isolated Testing: Tests can run independently of backend availability or data setup.
3. Custom Error Simulation: Easily replicate server errors to test frontend resilience.

Validating Network Requests and Responses

Validating network requests and responses ensures that your application communicates correctly with the backend and handles data accurately. This step is crucial for verifying API interactions, data integrity, and application stability. Let’s explore how to implement these validations in Cypress, focusing on request payloads, response structures, and schema validation using chai-json-schema.

Assertions on Request Payloads

Validating request payloads involves ensuring that the data sent to the server is correct and matches expected values. This is especially important for POST, PUT, and DELETE requests where data integrity is critical.

Example: Validating a POST Request Payload

Suppose your application submits a form, and you want to verify that the correct data is sent in the request body:

cy.intercept('POST', '/api/users', (req) => {
  // Assert request payload
  expect(req.body).to.have.property('name', 'John Doe');  // Assert 'name' property
  expect(req.body).to.have.property('email', 'john@example.com');  // Assert 'email' property
}).as('createUser');

// Trigger form submission by clicking the submit button
cy.get('#submitButton').click(); 

// Wait for the intercepted POST request
cy.wait('@createUser');

Explanation:

• Intercepting Request: Captures the POST request to /api/users.
• Payload Validation: Checks that the req.body contains the correct name and email fields.
• Real-World Use Case: Ensures form submissions or API calls send accurate data.

Example: Validating a PUT Request Payload

A PUT request typically updates an existing resource. You should ensure that the correct data is sent and that the server responds appropriately.

Imagine you have an endpoint /api/users/:id that updates a user’s profile. You want to validate the payload and confirm the response.

cy.intercept('PUT', '/api/users/101', (req) => {
  // Validate request payload
  expect(req.body).to.deep.equal({
    name: 'Jane Smith',
    email: 'jane.smith@example.com',
    age: 30,
  });

  // Mock a successful server response
  req.reply({
    statusCode: 200,
    body: {
      id: 101,
      name: 'Jane Smith',
      email: 'jane.smith@example.com',
      age: 30,
      updatedAt: '2024-11-23T12:34:56Z',
    },
  });
}).as('updateUser');

// Trigger the update action in your app
cy.get('#updateButton').click();

// Wait for the PUT request and validate the response
cy.wait('@updateUser').then((interception) => {
  // Validate response data
  expect(interception.response.statusCode).to.eq(200);
  expect(interception.response.body).to.have.property('updatedAt');
});

Explanation:

• Payload Validation: Checks that the request payload contains the correct updated user data (name, email, and age).
• Simulated Response: Returns a mocked 200 OK response with the updated user object, including an updatedAt timestamp.
• Frontend Interaction: Ensures that the update operation triggers correctly and handles the response appropriately.

Example: Validating a DELETE Request Payload

A DELETE request removes a resource, and you typically verify that the request is sent correctly and the application handles different deletion outcomes (success, errors).

Consider an endpoint /api/users/:id that deletes a user. You want to ensure the correct deletion behaviour based on the user ID.

cy.intercept('DELETE', '/api/users/101', (req) => {
  // Validate request method and URL
  expect(req.method).to.eq('DELETE');
  expect(req.url).to.contain('/api/users/101');
  
  // Log request details for debugging
  console.log('Intercepted DELETE request:', req);
  
  // Mock a successful deletion response
  req.reply({
    statusCode: 200,
    body: { message: 'User deleted successfully' },
  });
}).as('deleteUser');

// Trigger the delete action
cy.get('#deleteButton').click();

// Wait for the DELETE request and validate the response
cy.wait('@deleteUser').then((interception) => {
  // Validate response
  console.log('Response from DELETE request:', interception.response);
  expect(interception.response.statusCode).to.eq(200);
  expect(interception.response.body).to.have.property('message', 'User deleted successfully');
});

Explanation:

• Request Method Validation: Ensures the request method is DELETE and the correct user ID is in the URL.
• Mocked Response: Simulates a 200 OK response with a confirmation message.
• Frontend Interaction: Confirms the application handles the deletion process correctly by validating the response.

Validating Response Structures and Status Codes

Ensuring that API responses return the correct data structure and status code is essential for frontend stability and user experience.

Example: Validating a GET Request Response

Suppose your app fetches a user list, and you need to validate the response data:

// Intercepts the GET request to '/api/users' and assigns it an alias 'getUsers'
cy.intercept('GET', '/api/users').as('getUsers');

// Visits the '/users' page in the application
cy.visit('/users');

// Waits for the intercepted GET request to complete and performs assertions on the response
cy.wait('@getUsers').then((interception) => {
  // Asserts that the response status code is 200 (OK)
  expect(interception.response.statusCode).to.eq(200);

  // Asserts that the response body is an array
  expect(interception.response.body).to.be.an('array');
  
  // Asserts that the first item in the array has the expected keys: 'id', 'name', and 'email'
  expect(interception.response.body[0]).to.have.all.keys('id', 'name', 'email');
});

Explanation:

• Response Validation: Checks if the status code is 200 and that the response is an array of objects containing id, name, and email.
• Real-World Use Case: Ensures the frontend handles and displays data correctly based on API responses.

Example: Validating a POST Request Response

A POST request is used to create a new resource. It typically returns a 201 Created status code, along with the newly created resource’s details.

Example Scenario: Creating a New User

// Intercepts the POST request to '/api/users', validates the request body, and mocks the server response
cy.intercept('POST', '/api/users', (req) => {
  // Asserts that the request body contains the expected 'name' and 'email' properties
  expect(req.body).to.deep.equal({
    name: 'Alice Johnson', // Name in the request body
    email: 'alice.johnson@example.com', // Email in the request body
  });

  // Mocks a successful server response with status code 201 (Created) and the created user data
  req.reply({
    statusCode: 201, // Sets the HTTP status code to 201 (Created)
    body: {
      id: 102, // User ID
      name: 'Alice Johnson', // User name
      email: 'alice.johnson@example.com', // User email
      createdAt: '2024-11-23T14:20:00Z', // Timestamp of when the user was created
    },
  });
}).as('createUser');

// Simulates a click on the create user button to trigger the POST request
cy.get('#createUserButton').click();

// Waits for the intercepted POST request to complete and performs assertions on the response
cy.wait('@createUser').then((interception) => {
  // Asserts that the response status code is 201 (Created)
  expect(interception.response.statusCode).to.eq(201);

  // Asserts that the response body contains the 'id' property, indicating the created user ID
  expect(interception.response.body).to.have.property('id');

  // Asserts that the response body contains the 'createdAt' property, indicating the creation time
  expect(interception.response.body).to.have.property('createdAt');
});

Explanation:

• Request Payload Validation: Checks if the request sends the correct data.
• Mock Response: Returns a 201 status code, indicating successful resource creation.
• Response Assertions: Ensures the response body contains expected properties (id, createdAt).

Example: Validating a PUT Request Response

A PUT request updates an existing resource and often returns a 200 OK status code, reflecting the updated resource.

Example Scenario: Updating User Information

// Intercepts the PUT request to '/api/users/102', validates the request body, and mocks the server response
cy.intercept('PUT', '/api/users/102', (req) => {
  // Asserts that the request body contains the expected 'name' and 'email' properties for the updated user
  expect(req.body).to.deep.equal({
    name: 'Alice Updated', // Updated user name
    email: 'alice.updated@example.com', // Updated user email
  });

  // Mocks a successful server response with status code 200 (OK) and the updated user data
  req.reply({
    statusCode: 200, // Sets the HTTP status code to 200 (OK)
    body: {
      id: 102, // User ID
      name: 'Alice Updated', // Updated user name
      email: 'alice.updated@example.com', // Updated user email
      updatedAt: '2024-11-23T15:00:00Z', // Timestamp of when the user was updated
    },
  });
}).as('updateUser');

// Simulates a click on the update user button to trigger the PUT request
cy.get('#updateUserButton').click();

// Waits for the intercepted PUT request to complete and performs assertions on the response
cy.wait('@updateUser').then((interception) => {
  // Asserts that the response status code is 200 (OK)
  expect(interception.response.statusCode).to.eq(200);

  // Asserts that the response body contains the 'updatedAt' property, indicating the last update time
  expect(interception.response.body).to.have.property('updatedAt');
});

Example: Validating a DELETE Request Response

A DELETE request removes a resource and usually returns a 200 OK or 204 No Content status code. Validating this ensures the correct resource is deleted and the response is appropriately handled.

Example Scenario: Deleting a User

// Intercepts the DELETE request to '/api/users/102', validates the request method, and mocks the server response
cy.intercept('DELETE', '/api/users/102', (req) => {
  // Asserts that the request method is DELETE
  expect(req.method).to.eq('DELETE');

  // Mocks a successful server response with status code 200 (OK) and a success message
  req.reply({
    statusCode: 200, // Sets the HTTP status code to 200 (OK)
    body: { message: 'User deleted successfully' }, // Success message
  });
}).as('deleteUser');

// Simulates a click on the delete user button to trigger the DELETE request
cy.get('#deleteUserButton').click();

// Waits for the intercepted DELETE request to complete and performs assertions on the response
cy.wait('@deleteUser').then((interception) => {
  // Asserts that the response status code is 200 (OK)
  expect(interception.response.statusCode).to.eq(200);

  // Asserts that the response body contains the expected success message
  expect(interception.response.body.message).to.eq('User deleted successfully');
});

Using chai-json-schema for schema validation

For more robust validation, use JSON schema validation to ensure the response adheres to a defined structure. This is particularly useful when dealing with complex or nested data.

Setup chai-json-schema:

Install chai-json-schema as a development dependency:

npm install chai-json-schema --save-dev

Import and extend chai in your Cypress tests:

import chaiJsonSchema from 'chai-json-schema';
chai.use(chaiJsonSchema);

Example: Validating Response Schema

Suppose you expect the following schema for a user object:

// Define the user schema
const userSchema = {
  title: 'User Schema',
  type: 'object',
  required: ['id', 'name', 'email'],
  properties: {
    id: { type: 'number' },
    name: { type: 'string' },
    email: { type: 'string' },
  },
};

// Intercept the GET request to /api/users/101
cy.intercept('GET', '/api/users/101').as('getUser');

// Visit the user details page
cy.visit('/user/101');

// Wait for the intercepted request to complete
cy.wait('@getUser').then((interception) => {
  // Validate the response against the user schema
  expect(interception.response.body).to.be.jsonSchema(userSchema);
});

Best Practices for Network Validation:

1. Test Both Positive and Negative Scenarios: Ensure correct handling of success (200 OK) and error (400, 500) responses.
2. Validate Data Consistency: Ensure that data sent in requests matches data shown in the UI.
3. Use Fixtures for Consistent Data: Mock responses using Cypress fixtures to maintain test reliability.
4. Isolate Network-Dependent Tests: Avoid flaky tests by stubbing network calls to simulate consistent backend behaviour.

Modifying and Stubbing Responses in Cypress

Modifying and stubbing API responses in Cypress is a powerful technique that enables developers to simulate various server behaviours and conditions directly within their tests. By intercepting HTTP requests and defining custom responses, testers gain full control over the data returned to the application. This allows them to replicate scenarios such as server errors, slow responses, or invalid data, without relying on a live backend. This not only ensures that the frontend can gracefully handle different situations but also helps in testing edge cases that might be difficult or impractical to reproduce using real APIs.

Furthermore, stubbing responses improves test reliability and performance. Tests run faster because they avoid making network calls, and they’re more stable since they aren’t affected by backend changes or network issues. For example, you can simulate a 500 Internal Server Error response to verify that the application displays an appropriate error message. Similarly, you can stub slow responses to ensure that loading states or timeouts are correctly handled. This approach isolates the frontend logic, allowing developers to focus on verifying UI behaviour and error handling, leading to a more robust and well-tested application.

Overriding API responses with mocked data

Why Stub Responses?

1. Control Over Test Scenarios: 

Stubbing responses lets you simulate various API behaviours, such as server errors, timeouts, and successful data retrieval. This control helps you create predictable test environments where you can verify how the frontend handles different outcomes. For instance, you can simulate a 500 Internal Server Error to test whether your application displays an appropriate error message or gracefully handles the failure. This approach ensures that your UI behaves correctly under all conditions without needing to manipulate the backend.

2. Isolation from Backend Services: 

Stubbing allows you to test frontend components in isolation from the backend. By intercepting network requests and providing mock responses, your tests become independent of the server’s state or availability. This isolation ensures consistent test results and eliminates flakiness caused by backend changes, network issues, or data inconsistencies. For example, if the backend service is under development or temporarily down, you can still simulate API responses to continue testing the frontend functionality.

3. Improved Test Performance:

Real network requests can slow down test execution, especially when dealing with large datasets or slow backend responses. Stubbing API calls avoids these delays by providing immediate responses, significantly speeding up your test suite. This approach also reduces the dependency on external services, making it easier to run tests in CI/CD pipelines where network stability might be an issue. As a result, you can quickly validate frontend behaviour and ensure a more efficient testing process.

4. Facilitates Edge Case Testing:

Testing edge cases, such as invalid data or unexpected server responses, can be challenging with live APIs. Stubbing allows you to craft custom responses that mimic these scenarios, ensuring your application handles them gracefully. For example, you can simulate a 404 Not Found response to verify how the application handles missing resources or an empty dataset to check if fallback UI components render correctly.

Key Use Cases:

Simulate Server Errors:

Testing how your application handles failed requests is an essential part of ensuring a smooth user experience. You can simulate server errors such as 404 Not Found or 500 Internal Server Error, for instance, so that you’re sure appropriate error messages appear and the UI doesn’t break. For instance, you could stub a login request to return a 401 Unauthorised status, so that the application correctly prompts the user with an “Invalid credentials” message. This helps validate that the frontend gracefully handles errors and provides meaningful feedback to users.

Example: Simulating a Server Error

Let’s say you want to test how your login page behaves when the server returns an error.

// Intercept the POST request to /api/login and mock a 401 Unauthorized error
cy.intercept('POST', '/api/login', {
  statusCode: 401,
  body: {
    error: 'Invalid credentials', // Mock error response body
  },
}).as('loginError');

// Attempt to log in with incorrect credentials
cy.get('#username').type('wrongUser'); // Enter incorrect username
cy.get('#password').type('wrongPassword'); // Enter incorrect password
cy.get('#loginButton').click(); // Click the login button

// Wait for the intercepted request and validate UI behavior
cy.wait('@loginError'); // Wait for the loginError alias

// Validate that the error message is displayed in the UI
cy.get('.error-message').should('contain', 'Invalid credentials'); // Assert that the error message appears

Explanation:

• Intercepts the Request: Blocks the actual /api/login call.
• Stubs Response: Returns a 401 Unauthorised status with a custom error message.
• UI Validation: Checks that the application displays the correct error message.

Simulating Slow Responses

Hence, slow network responses would impact your user experience significantly; you have to ensure your application is tested under such conditions. A stubbed request with an intentional delay allows you to check if the loading indicators or timeout messages appear as they should when their requests are delayed. For example, you can simulate a slow response from a data-fetching API, and ensure that a loading spinner is visible until the data actually appears. This practice helps you verify users are being made aware of the processes under way, hence improving the application’s perceived performance.

Example: Simulating Slow Responses

Testing a loading spinner or timeout behaviour when the server takes too long to respond.

// Intercept the GET request to /api/data and simulate a delayed response
cy.intercept('GET', '/api/data', (req) => {
  req.reply((res) => {
    // Simulate a delay of 3 seconds before sending the response
    res.delay = 3000; // 3-second delay
    res.send({ data: [] }); // Respond with an empty data array
  });
}).as('slowData'); // Alias the intercepted request for later use

// Trigger the data fetch action by clicking the button
cy.get('#fetchDataButton').click(); // Click the fetch data button

// Verify that the loading spinner is visible during the data fetch
cy.get('.loading-spinner').should('be.visible'); // Assert that the loading spinner is shown

// Ensure that the loading spinner disappears after the response
cy.wait('@slowData'); // Wait for the slow data response to complete

cy.get('.loading-spinner').should('not.exist'); 
// Assert that the loading spinner is no longer visible

Explanation:

• Simulated Delay: The delay property adds a delay to the response.
• Loading State Check: Validates that the loading spinner appears while waiting for the data.
• Post-Response Validation: Ensures the spinner disappears once data is received.

Testing Fallback UI Behaviour:

Sometimes, the server may return empty data or partial content, and your application needs to deal with these situations properly. By simulating this way, you can test how the UI reacts to missing or incomplete data. For example, you can stub a request so that an empty array is returned, and check whether the application displays a “No data available” message instead of an empty or a broken interface. This ensures that the frontend can handle various data states without crashing or displaying confusing information.

Example: Modifying Response Data

Override the server response with custom data to simulate various states of the Application.

// Intercept the GET request to /api/profile and mock a response
cy.intercept('GET', '/api/profile', (req) => {
  req.reply({
    statusCode: 200, // Respond with a 200 status code
    body: {
      name: 'Test User', // Mock user name
      email: 'test.user@example.com', // Mock user email
      profileComplete: false, // Mock profile completion status
    },
  });
}).as('profileData'); // Alias the intercepted request for later use

// Trigger the profile fetch action by clicking the 'loadProfile' button
cy.get('#loadProfile').click(); // Click the button to load the profile data

// Wait for the intercepted profile data request to complete
cy.wait('@profileData'); // Wait for the mock response to be returned

// Validate that the UI shows a profile incomplete warning
cy.get('.profile-warning').should('contain', 'Profile incomplete'); // Assert the warning message is displayed

Explanation:

• Custom Data Injection: Stubbs the /api/profile endpoint with specific data.
• Simulates Incomplete State: Forces the application to render a UI warning for incomplete profiles.
• UI Check: Ensures the frontend correctly reflects the modified data.

Best Practices for Stubbing in Cypress:

• Combine with Assertions: Always verify both the request and the response to ensure expected behaviour.
• Test Edge Cases: Stub unusual responses, such as errors or empty data, to check how the application handles them.
• Use Fixtures: Store complex response data in external files to keep tests organised and maintainable.

Real-world Examples

Testing Pagination

Pagination is common in data-heavy applications, and ensuring correct navigation between pages is crucial. By stubbing multiple pages of data, you simulate how your app handles transitions between them.

// Intercept the GET request for page 1 and serve a fixture (page1.json)
cy.intercept('GET', '/api/items?page=1', { fixture: 'page1.json' }).as('getPage1');

// Intercept the GET request for page 2 and serve a fixture (page2.json)
cy.intercept('GET', '/api/items?page=2', { fixture: 'page2.json' }).as('getPage2');

// Load the items page
cy.visit('/items'); 

// Wait for the response of the first page load and confirm the data is correct
cy.wait('@getPage1');  // Wait for the page 1 data
cy.get('.item-list').should('contain', 'Item 1'); // Assert that 'Item 1' is present in the list

// Simulate user clicking the 'next page' button to load the next set of items
cy.get('.next-page-button').click(); 

// Wait for the response of the second page load and verify new data is loaded
cy.wait('@getPage2'); 
cy.get('.item-list').should('contain', 'Item 11'); // Assert that 'Item 11' is present in the list on page 2

Explanation:

• This test ensures your pagination logic correctly fetches and displays data from different pages. By using fixture files (page1.json and page2.json), you control what each page contains, ensuring predictable test outcomes.

Search Autocomplete

Autocomplete features rely on dynamic server responses. Testing this behaviour ensures suggestions update based on user input.

Intercepting search requests allows you to test autocomplete suggestions without relying on real data. This ensures the UI responds to search inputs dynamically.

// Intercept the GET request for the search query with 'app*' and mock the response
cy.intercept('GET', '/api/search?query=app*', {
  statusCode: 200,  // Set status code to 200 for a successful response
  body: ['apple', 'application', 'apparel'],  // Return mocked search results
}).as('searchResults');

// Simulate typing 'app' into the search box to trigger the API request
cy.get('#searchBox').type('app');

// Wait for the mock API response for search results
cy.wait('@searchResults');  // Wait for the search API to respond

// Verify that the correct number of suggestions is displayed
cy.get('.autocomplete-item').should('have.length', 3);  // Check that 3 suggestions are shown

// Verify that the first suggestion contains the word 'apple'
cy.get('.autocomplete-item').first().should('contain', 'apple');  // Assert that the first suggestion is 'apple'

Explanation:

• This example simulates typing in a search bar and tests that the correct autocomplete suggestions display. It validates both the count and content of suggestions, ensuring the UI responds correctly to partial inputs.

Handling Error Scenarios

Applications must gracefully handle server errors to avoid confusing users. Stubbing error responses helps test these failure scenarios effectively.

// Intercept the GET request for the profile API and mock a 500 error response
cy.intercept('GET', '/api/profile', {
  statusCode: 500,  // Mock a 500 Internal Server Error response
  body: { message: 'Internal Server Error' },  // Set the response body with an error message
}).as('getProfileError');

// Visit the profile page, which triggers the GET request for the profile API
cy.visit('/profile');

// Wait for the intercepted API request to complete and capture the mock error response
cy.wait('@getProfileError');

// Verify that the error message is displayed on the UI
cy.get('.error-message').should('contain', 'Something went wrong, please try again later');

Explanation:

• This test simulates a server failure on a profile page load. By checking the error message in the UI, you ensure the application handles backend failures with a user-friendly message, enhancing the overall experience.

Testing Form Submissions (PUT and DELETE Requests)

Stubbing these types of requests lets you verify that form submissions or data deletions work correctly without affecting real data.

PUT Example: Updating User Data

// Intercept the PUT request for updating user data and mock a successful response
cy.intercept('PUT', '/api/users/123', {
  statusCode: 200,  // Mock a successful 200 OK response
  body: { message: 'User updated successfully' },  // Mock the response body with a success message
}).as('updateUser');

// Trigger the update action by clicking the update button
cy.get('#updateButton').click();  // Simulate the button click to trigger the PUT request

// Wait for the intercepted API request to complete
cy.wait('@updateUser');

// Verify that the notification appears with the success message
cy.get('.notification').should('contain', 'User updated successfully');

DELETE Example: Deleting an Item

// Intercept the DELETE request to remove an item and mock a successful response with no content
cy.intercept('DELETE', '/api/items/456', {
  statusCode: 204,  // No Content status code, indicating successful deletion without a body
}).as('deleteItem');

// Trigger the delete action by clicking the delete button
cy.get('#deleteButton').click();  // Simulate the button click to trigger the DELETE request

// Wait for the intercepted DELETE request to complete
cy.wait('@deleteItem');

// Verify that the item is no longer present in the list after deletion
cy.get('.item-list').should('not.contain', 'Item 456');  // Ensure that 'Item 456' is removed from the list

Explanation:

• These examples show how to simulate PUT and DELETE requests to test form submissions or deletion functionality. They ensure that UI updates reflect the changes correctly without affecting real data.

• By using stubbing effectively in Cypress, you can simulate different API responses, test error handling, and ensure your application is robust under various conditions. This approach not only enhances test coverage but also boosts the reliability and performance of your test suite.

Working with Fixtures

Fixtures in Cypress serve as powerful tools to manage external test data effectively. They provide a way to store and load predefined data in JSON or other file formats, ensuring consistency and reusability across tests. Let’s break down how to utilise fixtures in different scenarios with detailed examples and explanations.

How to use Cypress fixtures for dynamic and reusable test data

What are Fixtures?

Fixtures are external files, usually in JSON format, that store static or mock data for your tests. These files reside in the fixtures folder within your Cypress project and can be referenced in tests to simulate various data-driven scenarios without making actual server requests. This approach decouples test logic from hardcoded values, making tests easier to maintain and scale.

---

Creating and Loading Fixtures

You can create a fixture file (user.json) in the cypress/fixtures directory with sample data:

cypress/fixtures/user.json
{
  "id": 1,
  "name": "Alice Johnson",
  "email": "alice.johnson@example.com"
}

Loading Fixtures in Tests: Fixtures are loaded into tests using the cy.fixture() method:

describe('User Profile Test', () => {
  it('Loads user data from fixture', () => {
    // Load user data from the 'user.json' fixture
    cy.fixture('user.json').then((userData) => {
      
      // Visit the profile page
      cy.visit('/profile');  
      
      // Fill the form with the fixture data
      cy.get('#name-input').type(userData.name);  // Enter the name from the fixture
      cy.get('#email-input').type(userData.email);  // Enter the email from the fixture
      
      // Click the submit button to trigger the form submission
      cy.get('#submit-button').click();
    });
  });
});

Explanation:

• This code demonstrates loading user data from a fixture and using it to fill out a profile form. This ensures consistency and avoids hardcoding values directly into the test.

Using Fixtures for API Stubbing

You can also use fixtures to stub API responses, simulating backend interactions without making real network requests. This is particularly useful for isolating frontend testing and ensuring consistent data across tests.

Example of Stubbing a GET Request:

// Intercept the GET request for '/api/users/1' and return the 'user.json' fixture as the response
cy.intercept('GET', '/api/users/1', { fixture: 'user.json' }).as('getUser');

// Visit the '/profile' page
cy.visit('/profile');

// Wait for the mocked API response for the intercepted request
cy.wait('@getUser');

// Assert that the profile name contains 'Alice Johnson'
cy.get('.profile-name').should('contain', 'Alice Johnson');

// Assert that the profile email contains 'alice.johnson@example.com'
cy.get('.profile-email').should('contain', 'alice.johnson@example.com');

Explanation:

• Here, Cypress intercepts a GET request to /api/users/1 and returns data from user.json. This allows you to verify that the profile page displays the correct user information without relying on an actual server response.

Dynamic Fixture Data

Sometimes, you need to modify fixture data dynamically during the test. Cypress allows you to alter loaded data before using it.

Example of Modifying Fixture Data at Runtime:

// Load the 'user.json' fixture and modify the data
cy.fixture('user.json').then((userData) => {
  userData.name = 'Bob Smith';  // Modify the fixture data

  // Intercept the GET request for '/api/users/1' and return the modified fixture data as the response
  cy.intercept('GET', '/api/users/1', { body: userData }).as('getModifiedUser');

  // Visit the '/profile' page
  cy.visit('/profile');

  // Wait for the modified API response for the intercepted request
  cy.wait('@getModifiedUser');

  // Assert that the profile name contains 'Bob Smith'
  cy.get('.profile-name').should('contain', 'Bob Smith');
});

Explanation:

• This approach allows you to customise fixture data for specific test scenarios. In this example, the name field is dynamically changed to Bob Smith, simulating different user data without creating multiple fixture files.

Using Multiple Fixtures

For more complex tests, you might need different sets of data. You can create multiple fixture files and load them as needed.

Example with Multiple Fixtures:

// Intercept the GET request for '/api/users/1' and return the 'user1.json' fixture as the response
cy.intercept('GET', '/api/users/1', { fixture: 'user1.json' }).as('getUser1');

// Intercept the GET request for '/api/users/2' and return the 'user2.json' fixture as the response
cy.intercept('GET', '/api/users/2', { fixture: 'user2.json' }).as('getUser2');

// Visit the '/users/1' page
cy.visit('/users/1');

// Wait for the intercepted request for user1 data
cy.wait('@getUser1');

// Assert that the user name contains 'Alice Johnson'
cy.get('.user-name').should('contain', 'Alice Johnson');

// Visit the '/users/2' page
cy.visit('/users/2');

// Wait for the intercepted request for user2 data
cy.wait('@getUser2');

// Assert that the user name contains 'Bob Smith'
cy.get('.user-name').should('contain', 'Bob Smith');

Explanation:

• This setup tests different user profiles by intercepting requests with separate fixture files (user1.json and user2.json). It validates that the application correctly handles distinct data sets.

Benefits of Using Fixtures in Cypress

• Consistency: Ensures the same data is used across multiple test runs, reducing flakiness.
• Reusability: Centralizes test data, allowing it to be reused in different tests.
• Maintainability: Simplifies updates—change the fixture file once, and all related tests reflect the update.
• Isolation: Simulates server responses without depending on backend availability or state.

By leveraging fixtures, you can enhance your Cypress test suite’s reliability and maintainability, creating more robust and flexible automation scripts. This approach not only improves test accuracy but also streamlines the process of handling dynamic data scenarios.

Best Practices and Common Pitfalls

Effective network request interception in Cypress enhances test reliability and ensures you can simulate various backend responses. However, adhering to best practices and avoiding common pitfalls is crucial to maintaining a robust and maintainable test suite.

Naming and Organizing cy.intercept Commands for maintainability

Best Practice:
Always provide meaningful names or aliases for your intercepted routes using .as(). This ensures better readability and easier debugging, especially when dealing with multiple intercepts in a single test.

Example:

// Intercept the GET request for '/api/users' and return the 'users.json' fixture as the response

cy.intercept('GET', '/api/users', { fixture: 'users.json' }).as('getUsers');

// Wait for the intercepted request using the alias for better readability

cy.wait('@getUsers');

// Assert that the user list contains exactly 5 items

cy.get('.user-list').should('have.length', 5);

Ensuring Tests Remain Independent and Reusable

Best Practice:
Design each test to be self-contained. Avoid relying on shared state or data from previous tests. Reset or stub necessary network requests at the beginning of each test.

Example:

// Run before each test case to set up the intercept and visit the '/orders' page

beforeEach(() => {

  // Intercept the GET request for '/api/orders' and return the 'orders.json' fixture as the response

  cy.intercept('GET', '/api/orders', { fixture: 'orders.json' }).as('getOrders');

  // Always reset state by visiting the '/orders' page

  cy.visit('/orders');

});

Why It Matters:
Independent tests reduce the risk of flaky behaviour caused by unexpected state or data carryover. This approach ensures tests can be run in any order without impacting their outcomes.

Handling Flaky Tests Caused by Network Delays or Third-Party APIs

Best Practice:
Mock third-party API responses using fixtures or hard coded data to avoid reliance on external services. Configure network request timeouts and retries appropriately.

Example:

// Intercept the POST request for '/api/payment' and mock a successful response with status code 200

cy.intercept('POST', '/api/payment', { statusCode: 200, body: { success: true } }).as('postPayment');

// Click the pay button to trigger the payment request

cy.get('#pay-button').click();

// Wait for the intercepted POST request and assert that the response status code is 200

cy.wait('@postPayment').its('response.statusCode').should('eq', 200);

Common Pitfall:

Not stubbing third-party services can lead to tests failing due to network instability or external service downtime. This introduces flakiness, especially when testing critical paths like payment processing or authentication.

Managing Dynamic Data in Intercepts

Best Practice:
Use dynamic stubbing for variable responses, such as unique IDs or timestamps, to simulate real-world scenarios more accurately.

Example:

// Intercept the GET request for '/api/user/*' and dynamically modify the response

cy.intercept('GET', '/api/user/*', (req) => {

  // Reply with a custom response, using the last part of the URL as the user ID and setting the name to 'Dynamic User'

  req.reply({

    statusCode: 200,

    body: { id: req.url.split('/').pop(), name: 'Dynamic User' }

  });

}).as('getUser');

Why It Matters:
Simulating dynamic data ensures your tests can handle real-world scenarios involving unique or changing values. It also prevents hard coded responses from creating false positives.

Logging and Debugging

Best Practice:
Enable logging for network requests to easily debug intercepted routes and responses. Cypress provides built-in tools like cy.log() or console.log() for better visibility.

Example:

// Intercept the GET request for '/api/users' and log the request details to the console

cy.intercept('GET', '/api/users', (req) => {

  console.log('Intercepted request:', req);

}).as('logUsers');

// Visit the '/users' page to trigger the intercepted request

cy.visit('/users');

Why It Matters:

Detailed logs help diagnose failures related to network requests. They provide insights into request payloads and responses, making troubleshooting more efficient.

Key Takeaways:

• Naming intercepts with aliases improves readability and debugging.
• Independent tests prevent flaky behaviour due to shared state.
• Mocking external services ensures stable, predictable tests.
• Dynamic stubbing makes tests more realistic and adaptable.
• Logging network activity aids in identifying and resolving issues quickly.

By following these best practices, you can leverage Cypress’s powerful network interception capabilities to create reliable, maintainable, and efficient automated tests.

Debugging Network Interception

Using cy.log and Cypress’s built-in network logging

Efficient debugging of network interceptions in Cypress ensures your tests are reliable and easier to maintain. When intercepting network requests, identifying issues early can prevent test failures caused by unexpected API behaviour. Here’s a detailed breakdown of essential tools and techniques for debugging intercepted requests effectively.

Using cy.log() for Network Insights

Cypress’s cy.log() method is useful for logging custom messages, providing visibility into request and response data during test execution.

Example:

// Intercept the GET request for '/api/users' and create an alias for it
cy.intercept('GET', '/api/users').as('getUsers');

// Wait for the intercepted request and log the response status and body
cy.wait('@getUsers').then((interception) => {
  // Log the response status code to the console
  cy.log('Response Status:', interception.response.statusCode);  
  
  // Log the response body to the console
  cy.log('Response Body:', JSON.stringify(interception.response.body));  
});

Explanation:

• This example logs key details from the intercepted response. cy.log() outputs this information directly into the Cypress Test Runner, making it easy to verify request outcomes without opening the developer console.

Leveraging console.log() for Detailed Debugging

For more complex data structures or scenarios where cy.log() is insufficient, console.log() provides deeper insights.

Example:

// Intercept the POST request for '/api/orders' and create an alias for it
cy.intercept('POST', '/api/orders').as('postOrder');

// Click the submit button to trigger the POST request
cy.get('#submit-button').click();

// Wait for the intercepted POST request and log the interception details and request payload
cy.wait('@postOrder').then((interception) => {
  // Log the full interception object to the console
  console.log('Full Interception Object:', interception);
  
  // Log the request payload (body) to the console
  console.log('Request Payload:', interception.request.body);
});

Explanation:

• This logs the entire interception object to the browser console, allowing you to inspect the request, response, headers, and other metadata. It’s especially helpful when debugging complex API interactions or verifying payload structures.

Tools and techniques to debug intercepted requests

Accessing Cypress Network Logs in DevTools

Cypress automatically logs all network interceptions in the browser’s Developer Tools, providing a real-time view of network traffic.

Steps:

1. Open Developer Tools (Right-click → Inspect → Network tab).
2. Run your Cypress test.
3. Observe the intercepted requests under the “XHR” filter.

Tip: Use Cypress’s built-in logging along with DevTools for a comprehensive view, combining automated and manual inspection.

Debugging with the Cypress Command Log

The Cypress Command Log displays intercepted requests directly in the Test Runner. Click on any intercepted request to view its details, including request headers and body.

Example Interaction Flow:

1. Run the test in Cypress Test Runner.
2. Click on the network intercept in the Command Log.
3. Review details such as request method, URL, response time, and payload.

Verifying Intercepted Data with Assertions

Assertions help ensure intercepted responses meet expected criteria. They also serve as implicit debugging tools by failing tests if unexpected data is encountered.

Example:

// Intercept the GET request for '/api/users' and create an alias for it
cy.intercept('GET', '/api/users').as('getUsers');

// Wait for the intercepted request and assert that the response status code is 200
cy.wait('@getUsers').its('response.statusCode').should('eq', 200);

// Wait for the intercepted request again and assert that the response body contains 5 users
cy.wait('@getUsers').its('response.body').should('have.length', 5); // Ensure 5 users are returned

Explanation:

• This code checks that the response status is 200 and that the response body contains five user objects. If either condition fails, the test output provides detailed failure messages, aiding in debugging.

Debugging Failed Interceptions

When an intercepted request fails unexpectedly, investigate the failure by checking:

• The exact URL requested.
• Request and response headers.
• Response body for error messages.

Example of Handling Error Scenarios:

// Intercept the GET request for '/api/users' and mock a 500 status with an error message
cy.intercept('GET', '/api/users', { statusCode: 500, body: { error: 'Internal Server Error' }}).as('getUsers');

// Visit the '/users' page to trigger the intercepted request
cy.visit('/users');

// Wait for the intercepted request and assert that the response status code is 500
cy.wait('@getUsers').then((interception) => {
  // Assert that the response status code is 500
  expect(interception.response.statusCode).to.equal(500);
  
  // Log the error message from the response body
  cy.log('Error:', interception.response.body.error);
});

Explanation:

• This simulates a server error, verifying how the application handles a 500 status. Debugging focuses on ensuring the correct error message is displayed, preventing unexpected behaviour in production.

Key Takeaways:

• Use cy.log() for quick insights and console.log() for deeper inspection.
• Combine Cypress Command Log with browser DevTools for comprehensive debugging.
• Assertions verify responses and serve as built-in checks, highlighting potential issues early.

Mastering these debugging techniques ensures your Cypress tests are resilient, maintainable, and capable of handling complex network interactions effectively.

Conclusion

Intercepting network requests in Cypress unlocks powerful capabilities for simulating backend interactions, improving test reliability, and handling complex scenarios. Throughout this guide, we’ve explored essential concepts—from setting up cy.intercept() to handling dynamic responses and debugging techniques. By leveraging these tools effectively, you can simulate various API behaviours, test edge cases, and ensure your application behaves as expected under different conditions.

Remember to follow best practices, such as using meaningful aliases, stubbing external services, and verifying response data with assertions. This approach ensures that your tests are maintainable, resilient, and adaptable to real-world challenges.

Encourage experimentation with advanced interception scenarios, such as dynamic request handling and error simulations. Mastering these techniques will strengthen your automation skills, making you a more effective QA engineer in the world of modern web testing.

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