TypeScript support for custom commands in Cypress - Framework Patterns

Framework Mode - TypeScript support for custom commands

Folder Structure

  cypress/
  ├── e2e/                  # Test specs written in TypeScript
  │   └── example.cy.ts
  ├── support/              # Support files and custom commands
  │   ├── commands.ts       # Custom commands definitions
  │   ├── index.ts          # Support file to import commands and setup
  │   └── types.d.ts        # TypeScript declaration for custom commands
  ├── fixtures/             # Test data files
  │   └── example.json
  cypress.config.ts          # Cypress configuration in TypeScript
  tsconfig.json              # TypeScript configuration
  package.json
  

Test Framework Layers

• Test Specs (cypress/e2e): Write tests using custom commands with full TypeScript support.
• Custom Commands (cypress/support/commands.ts): Define reusable commands extending Cypress commands.
• Type Declarations (cypress/support/types.d.ts): Extend Cypress namespace to add typings for custom commands.
• Support Index (cypress/support/index.ts): Import custom commands and setup global hooks.
• Configuration (cypress.config.ts): Configure Cypress settings, including TypeScript support.

Configuration Patterns

• TypeScript Setup: Use tsconfig.json to configure compiler options for Cypress and support files.
• Custom Commands Declaration: Use cypress/support/types.d.ts to declare custom commands in the Cypress namespace for IntelliSense and type checking.
• Import Commands: Import commands.ts in index.ts to register commands globally.
• Environment Variables: Use cypress.config.ts to manage environment-specific settings and credentials securely.

Test Reporting and CI/CD Integration

• Use Cypress built-in reporters or plugins like mochawesome for detailed HTML and JSON reports.
• Configure cypress.config.ts to enable video recording and screenshots on failure for better debugging.
• Integrate Cypress tests in CI/CD pipelines (GitHub Actions, GitLab CI, Jenkins) using npx cypress run with TypeScript support.
• Publish reports as artifacts in CI to track test results over time.

Best Practices

• Strong Typing: Always declare custom commands in types.d.ts to get autocomplete and avoid runtime errors.
• Single Responsibility: Keep custom commands focused on one task for easier maintenance and reuse.
• Import Commands Once: Import all custom commands in support/index.ts to ensure they are available globally.
• Use Fixtures: Combine custom commands with fixtures for data-driven testing.
• Keep Config Clean: Manage environment variables and browser options in cypress.config.ts for flexibility.

Self Check

Where would you add a new custom command for logging in a user with TypeScript support in this framework structure?

Key Result

Organize Cypress tests with TypeScript by defining custom commands in support files with proper type declarations for strong typing and global availability.

Practice

1. What is the main benefit of adding TypeScript support for custom commands in Cypress?

easy

A. It makes tests run faster by optimizing command execution.

B. It provides type checking and better editor autocomplete for custom commands.

C. It automatically generates test reports for custom commands.

D. It allows running tests on multiple browsers simultaneously.

Solution

1. Step 1: Understand TypeScript role in Cypress

   TypeScript adds static type checking and editor support to catch errors early.

2. Step 2: Identify benefit for custom commands

   Typing custom commands improves autocomplete and prevents mistakes when using them.

3. Final Answer:

   It provides type checking and better editor autocomplete for custom commands. -> Option B

4. Quick Check:

   TypeScript support = type checking + autocomplete [OK]

Hint: TypeScript helps catch errors before running tests [OK]

Common Mistakes:

• Confusing TypeScript support with test speed improvements
• Thinking it auto-generates reports
• Believing it enables multi-browser runs

2. Which is the correct way to declare a custom command with TypeScript support in Cypress?

easy

A. namespace Cypress { interface myCommand { Chainable(): void } }

B. interface Cypress { Chainable { myCommand(): void } }

C. declare interface Cypress { myCommand(): void }

D. declare namespace Cypress { interface Chainable { myCommand(): Chainable<void> } }

Solution

1. Step 1: Recall TypeScript declaration syntax for Cypress commands

   Custom commands are declared inside the Cypress namespace extending Chainable interface.

2. Step 2: Match correct syntax

   declare namespace Cypress { interface Chainable { myCommand(): Chainable<void> } } correctly uses 'declare namespace Cypress' and extends 'Chainable' with 'myCommand'.

3. Final Answer:

   declare namespace Cypress { interface Chainable { myCommand(): Chainable<void> } } -> Option D

4. Quick Check:

   Namespace + Chainable interface = correct declaration [OK]

Hint: Custom commands extend Cypress.Chainable interface inside namespace [OK]

Common Mistakes:

• Missing 'declare' keyword
• Incorrect interface or namespace nesting
• Placing method outside Chainable interface

3. Given this TypeScript declaration for a custom command:

declare namespace Cypress {
  interface Chainable {
    login(email: string, password: string): Chainable<void>
  }
}

What is the correct way to use this login command in a test?

medium

A. cy.login(['[e-mail]', 'pass123'])

B. cy.login(email: '[e-mail]', password: 'pass123')

C. cy.login('[e-mail]', 'pass123')

D. cy.login()

Solution

1. Step 1: Understand method signature

   The login command takes two string arguments: email and password.

2. Step 2: Match correct usage syntax

   cy.login('[e-mail]', 'pass123') calls login with two string arguments in order, matching the declaration.

3. Final Answer:

   cy.login('[e-mail]', 'pass123') -> Option C

4. Quick Check:

   Method call with two string args = correct usage [OK]

Hint: Pass arguments as ordered parameters, not as object or array [OK]

Common Mistakes:

• Using named parameters syntax (not valid in JS calls)
• Passing arguments as array instead of separate params
• Calling without required arguments

4. You wrote this custom command declaration:

declare namespace Cypress {
  interface Chainable {
    clickButton(): void
  }
}

But when you use cy.clickButton() in your test, TypeScript shows an error. What is the problem?

medium

A. The return type should be Chainable<void>, not void.

B. The method name cannot be clickButton.

C. Custom commands must be declared outside the Cypress namespace.

D. You forgot to import Cypress in the test file.

Solution

1. Step 1: Check return type for custom commands

   Custom commands should return Chainable<T> to allow chaining in Cypress.

2. Step 2: Identify mismatch causing TypeScript error

   Returning void breaks chaining and causes TypeScript to complain.

3. Final Answer:

   The return type should be Chainable<void>, not void. -> Option A

4. Quick Check:

   Custom commands must return Chainable for chaining [OK]

Hint: Custom commands return Chainable, not void [OK]

Common Mistakes:

• Using void return type instead of Chainable
• Declaring commands outside Cypress namespace
• Assuming method names are restricted

5. You want to create a custom command fillForm that accepts an object with optional name and email fields. How should you declare it in TypeScript to support chaining and optional properties?

hard

A. declare namespace Cypress { interface Chainable { fillForm(data: { name?: string; email?: string }): Chainable<void> } }

B. declare namespace Cypress { interface Chainable { fillForm(data: { name: string; email: string }): void } }

C. declare namespace Cypress { interface Chainable { fillForm(data?: { name: string; email: string }): Chainable<void> } }

D. declare namespace Cypress { interface Chainable { fillForm(data: { name: string; email?: string }): Chainable<string> } }

Solution

1. Step 1: Define optional properties correctly

   Use question marks (?) to mark properties as optional in the data object.

2. Step 2: Ensure return type supports chaining

   Return type must be Chainable<void> to allow chaining in Cypress tests.

3. Final Answer:

   declare namespace Cypress { interface Chainable { fillForm(data: { name?: string; email?: string }): Chainable<void> } } -> Option A

4. Quick Check:

   Optional props + Chainable return = correct declaration [OK]

Hint: Use '?' for optional props and Chainable<void> return [OK]

Common Mistakes:

• Forgetting '?' for optional properties
• Using void return type instead of Chainable
• Returning wrong Chainable generic type