Mocha Interview Questions Your Guide to Success

Mocha is a feature-rich JavaScript test framework running on Node.js, making asynchronous testing simple and flexible. Stark.ai offers a curated collection of Mocha interview questions, real-world scenarios, and expert guidance to help you excel in your next technical interview.

Fundamentals & Core Concepts 10
Assertions & Testing Patterns 10
Hooks & Test Organization 10
Asynchronous Testing 10
Mocking & Stubbing 10
Test Organization & Structure 10
Performance & Optimization 10
Integration Testing 10
Security Testing 10
Continuous Integration & Deployment 10
Reporter & Output 10
Performance Testing 10

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mocha

Fundamentals & Core Concepts
- What is Mocha and what are its key features?
  
  Mocha is a feature-rich JavaScript test framework running on Node.js and browser. Key features include: 1) Flexible...
- How do you set up Mocha in a project?
  
  Setup involves: 1) Installing Mocha: npm install --save-dev mocha, 2) Adding test script to package.json: {...
- What are describe() and it() functions in Mocha?
  
  describe() is used to group related tests (test suite), while it() defines individual test cases. Example:...
- How does Mocha handle asynchronous tests?
  
  Mocha handles async testing through: 1) done callback parameter, 2) Returning promises, 3) async/await syntax....
- What are hooks in Mocha and how are they used?
  
  Mocha provides hooks: 1) before() - runs once before all tests, 2) beforeEach() - runs before each test, 3) after()...
- How do you use assertion libraries with Mocha?
  
  Mocha works with various assertion libraries: 1) Node's assert module, 2) Chai for BDD/TDD assertions, 3) Should.js...
- What are the different reporting options in Mocha?
  
  Mocha offers various reporters: 1) spec - hierarchical test results, 2) dot - minimal dots output, 3) nyan - fun...
- How do you skip or mark tests as pending in Mocha?
  
  Tests can be skipped/pending using: 1) it.skip() - skip test, 2) describe.skip() - skip suite, 3) it() without...
- What are exclusive tests in Mocha?
  
  Exclusive tests using .only(): 1) it.only() runs only that test, 2) describe.only() runs only that suite, 3)...
- How do you handle timeouts in Mocha tests?
  
  Timeout handling: 1) Set suite timeout: this.timeout(ms), 2) Set test timeout: it('test', function(done) {...
Assertions & Testing Patterns
- What assertion libraries can be used with Mocha?
  
  Mocha supports multiple assertion libraries: 1) Node's built-in assert module, 2) Chai for BDD/TDD assertions, 3)...
- How do you use Chai assertions in Mocha?
  
  Using Chai involves: 1) Installing: npm install chai, 2) Importing desired interface (expect, should, assert), 3)...
- What are the different assertion styles in Chai?
  
  Chai offers three styles: 1) Assert - traditional TDD style (assert.equal()), 2) Expect - BDD style with expect()...
- How do you handle asynchronous assertions?
  
  Async assertions handled through: 1) Using done callback, 2) Returning promises, 3) Async/await syntax, 4)...
- What are the common assertion patterns in Mocha?
  
  Common patterns include: 1) Equality checking (equal, strictEqual), 2) Type checking (typeOf, instanceOf), 3) Value...
- How do you test exceptions with assertions?
  
  Exception testing approaches: 1) expect(() => {}).to.throw(), 2) assert.throws(), 3) Testing specific error types,...
- What are chainable assertions in Chai?
  
  Chainable assertions allow: 1) Fluent interface with natural language, 2) Combining multiple checks, 3) Negating...
- How do you test object properties?
  
  Object property testing: 1) Check property existence, 2) Verify property values, 3) Test nested properties, 4)...
- What are assertion plugins and how are they used?
  
  Assertion plugins: 1) Extend assertion capabilities, 2) Add custom assertions, 3) Integrate with testing tools, 4)...
- How do you handle deep equality assertions?
  
  Deep equality testing: 1) Use deep.equal for objects/arrays, 2) Compare nested structures, 3) Handle circular...
Hooks & Test Organization
- What are the different types of hooks in Mocha?
  
  Mocha provides four types of hooks: 1) before() - runs once before all tests, 2) beforeEach() - runs before each...
- How do you handle asynchronous operations in hooks?
  
  Async hooks can be handled through: 1) done callback, 2) returning promises, 3) async/await syntax, 4) proper error...
- What is the execution order of hooks in Mocha?
  
  Hook execution order: 1) before() at suite level, 2) beforeEach() from outer to inner, 3) test execution, 4)...
- How do you share context between hooks and tests?
  
  Context sharing methods: 1) Using this keyword, 2) Shared variables in closure, 3) Hook-specific context objects, 4)...
- What is the purpose of describe blocks in test organization?
  
  describe blocks serve to: 1) Group related tests, 2) Create test hierarchy, 3) Share setup/teardown code, 4)...
- How do you handle cleanup in hooks?
  
  Cleanup handling: 1) Use afterEach/after hooks, 2) Clean shared resources, 3) Reset state between tests, 4) Handle...
- What are root level hooks?
  
  Root level hooks: 1) Apply to all test files, 2) Set up global before/after hooks, 3) Handle common setup/teardown,...
- How do you handle errors in hooks?
  
  Hook error handling: 1) Try-catch blocks in hooks, 2) Promise error handling, 3) Error reporting in hooks, 4)...
- What are best practices for hook usage?
  
  Hook best practices: 1) Keep hooks focused, 2) Minimize hook complexity, 3) Clean up resources properly, 4) Handle...
- How do you handle timeouts in hooks?
  
  Hook timeout handling: 1) Set hook-specific timeouts, 2) Configure global timeouts, 3) Handle async timeouts, 4)...
Asynchronous Testing
- What are the different ways to handle asynchronous tests in Mocha?
  
  Mocha supports multiple async patterns: 1) Using done callback, 2) Returning promises, 3) async/await syntax, 4)...
- How does the done callback work in Mocha?
  
  done callback: 1) Signals test completion, 2) Must be called exactly once, 3) Can pass error as argument, 4) Has...
- How do you test promises in Mocha?
  
  Promise testing: 1) Return promise from test, 2) Chain .then() and .catch(), 3) Use promise assertions, 4) Handle...
- How do you use async/await in Mocha tests?
  
  async/await usage: 1) Mark test function as async, 2) Use await for async operations, 3) Handle errors with...
- How do you handle timeouts in async tests?
  
  Timeout handling: 1) Set test timeout with this.timeout(), 2) Configure global timeouts, 3) Handle slow tests...
- What are common pitfalls in async testing?
  
  Common pitfalls: 1) Forgetting to return promises, 2) Missing done() calls, 3) Multiple done() calls, 4) Improper...
- How do you test event emitters asynchronously?
  
  Event testing: 1) Listen for events with done, 2) Set appropriate timeouts, 3) Verify event data, 4) Handle multiple...
- What is the purpose of async hooks in Mocha?
  
  Async hooks: 1) Setup async resources, 2) Clean up async operations, 3) Handle async dependencies, 4) Manage async...
- How do you handle sequential async operations?
  
  Sequential handling: 1) Chain promises properly, 2) Use async/await, 3) Maintain operation order, 4) Handle errors...
- What are best practices for async testing?
  
  Best practices: 1) Always handle errors, 2) Set appropriate timeouts, 3) Clean up resources, 4) Avoid nested...
Mocking & Stubbing
- What is the difference between mocks and stubs?
  
  Key differences include: 1) Stubs provide canned answers to calls, 2) Mocks verify behavior and interactions, 3)...
- What mocking libraries can be used with Mocha?
  
  Common mocking libraries: 1) Sinon.js for comprehensive mocking, 2) Jest mocks when using Jest, 3) testdouble.js for...
- How do you create a basic stub with Sinon?
  
  Creating stubs with Sinon: 1) sinon.stub() creates stub function, 2) .returns() sets return value, 3) .throws()...
- What are spies and how are they used?
  
  Spies are used to: 1) Track function calls, 2) Record arguments, 3) Check call count, 4) Verify call order, 5)...
- How do you mock HTTP requests?
  
  HTTP mocking approaches: 1) Use Nock for HTTP mocks, 2) Mock fetch/axios globally, 3) Stub specific endpoints, 4)...
- What is module mocking and how is it implemented?
  
  Module mocking involves: 1) Using Proxyquire or similar tools, 2) Replacing module dependencies, 3) Mocking specific...
- How do you verify mock/stub calls?
  
  Call verification includes: 1) Check call count with calledOnce/Twice, 2) Verify arguments with calledWith, 3) Check...
- What are sandboxes in Sinon and why use them?
  
  Sinon sandboxes: 1) Group mocks/stubs together, 2) Provide automatic cleanup, 3) Isolate test setup, 4) Prevent mock...
- How do you handle mock cleanup?
  
  Mock cleanup approaches: 1) Use afterEach hooks, 2) Implement sandbox restoration, 3) Reset individual mocks, 4)...
- What are fake timers and how are they used?
  
  Fake timers: 1) Mock Date/setTimeout/setInterval, 2) Control time progression, 3) Test time-dependent code, 4)...
Test Organization & Structure
- What are the best practices for organizing test files?
  
  Best practices include: 1) Mirror source code structure, 2) Use consistent naming conventions (.test.js, .spec.js),...
- How should describe blocks be structured?
  
  describe blocks should: 1) Group related test cases, 2) Follow logical hierarchy, 3) Use clear, descriptive names,...
- What are the guidelines for writing test descriptions?
  
  Test descriptions should: 1) Be clear and specific, 2) Describe expected behavior, 3) Use consistent terminology, 4)...
- How do you handle test dependencies?
  
  Handle dependencies by: 1) Using before/beforeEach hooks, 2) Creating shared fixtures, 3) Implementing test helpers,...
- What is the purpose of test hooks in organization?
  
  Test hooks serve to: 1) Set up test prerequisites, 2) Clean up after tests, 3) Share common setup logic, 4) Manage...
- How should test utilities be organized?
  
  Test utilities should be: 1) Placed in separate helper files, 2) Grouped by functionality, 3) Made reusable across...
- What is the role of test fixtures?
  
  Test fixtures: 1) Provide test data, 2) Set up test environment, 3) Ensure consistent test state, 4) Reduce setup...
- How do you maintain test independence?
  
  Maintain independence by: 1) Cleaning up after each test, 2) Avoiding shared state, 3) Using fresh fixtures, 4)...
- What are common test file naming conventions?
  
  Common conventions: 1) .test.js suffix, 2) .spec.js suffix, 3) Match source file names, 4) Use descriptive prefixes,...
- How should test configurations be managed?
  
  Config management: 1) Use .mocharc.js file, 2) Separate environment configs, 3) Manage test timeouts, 4) Set...
Performance & Optimization
- What factors affect test execution speed in Mocha?
  
  Key factors include: 1) Number and complexity of tests, 2) Async operation handling, 3) Test setup/teardown...
- How can you measure test execution time?
  
  Measuring methods: 1) Use --reporter spec for timing info, 2) Implement custom reporters for timing, 3) Use...
- What are best practices for optimizing test setup?
  
  Setup optimization: 1) Use beforeAll for one-time setup, 2) Minimize per-test setup, 3) Share setup when possible,...
- How do you identify slow tests?
  
  Identification methods: 1) Use --slow flag to mark slow tests, 2) Implement timing reporters, 3) Monitor test...
- What is the impact of hooks on test performance?
  
  Hook impacts: 1) Setup/teardown overhead, 2) Resource allocation costs, 3) Database operation time, 4) File system...
- How can test parallelization improve performance?
  
  Parallelization benefits: 1) Reduced total execution time, 2) Better resource utilization, 3) Concurrent test...
- What is the role of timeouts in test performance?
  
  Timeout considerations: 1) Default timeout settings, 2) Per-test timeouts, 3) Hook timeouts, 4) Async operation...
- How do you optimize async test execution?
  
  Async optimization: 1) Use proper async patterns, 2) Avoid unnecessary waiting, 3) Implement efficient promises, 4)...
- What impact does mocking have on performance?
  
  Mocking impacts: 1) Mock creation overhead, 2) Stub implementation efficiency, 3) Mock cleanup costs, 4) Memory...
- How can test data management affect performance?
  
  Data management impacts: 1) Data creation time, 2) Cleanup overhead, 3) Database operations, 4) Memory usage, 5) I/O...
Integration Testing
- What is integration testing and how does it differ from unit testing?
  
  Integration testing involves: 1) Testing multiple components together, 2) Verifying component interactions, 3)...
- How do you set up integration tests in Mocha?
  
  Setup involves: 1) Configuring test environment, 2) Setting up test databases, 3) Managing external services, 4)...
- What are common integration test patterns?
  
  Common patterns include: 1) Database integration testing, 2) API endpoint testing, 3) Service integration testing,...
- How do you handle test data in integration tests?
  
  Test data handling: 1) Use test databases, 2) Implement data seeding, 3) Clean up test data, 4) Manage test state,...
- What are best practices for database integration testing?
  
  Database testing practices: 1) Use separate test database, 2) Implement transactions, 3) Clean up after tests, 4)...
- How do you test API endpoints?
  
  API testing involves: 1) Making HTTP requests, 2) Verifying responses, 3) Testing error cases, 4) Checking...
- What are strategies for handling external services?
  
  External service strategies: 1) Use test doubles when needed, 2) Configure test endpoints, 3) Handle authentication,...
- How do you ensure test isolation in integration tests?
  
  Test isolation methods: 1) Clean database between tests, 2) Reset service state, 3) Use transactions, 4) Implement...
- What role do hooks play in integration testing?
  
  Hooks are used for: 1) Setting up test environment, 2) Database preparation, 3) Service initialization, 4) Resource...
- How do you handle asynchronous operations in integration tests?
  
  Async handling includes: 1) Using async/await, 2) Proper timeout configuration, 3) Handling promises, 4) Managing...
Security Testing
- What is security testing in Mocha and why is it important?
  
  Security testing involves: 1) Testing authentication mechanisms, 2) Verifying authorization controls, 3) Testing...
- How do you test authentication in Mocha?
  
  Authentication testing includes: 1) Testing login functionality, 2) Verifying token handling, 3) Testing session...
- What are best practices for testing authorization?
  
  Authorization testing practices: 1) Test role-based access, 2) Verify permission levels, 3) Check resource access,...
- How do you test input validation?
  
  Input validation testing: 1) Test for XSS attacks, 2) Check SQL injection, 3) Validate data formats, 4) Test...
- What are common security test patterns?
  
  Common patterns include: 1) Authentication testing, 2) Authorization checks, 3) Input validation, 4) Session...
- How do you test session management?
  
  Session testing involves: 1) Test session creation, 2) Verify session expiration, 3) Check session isolation, 4)...
- What is CSRF testing and how is it implemented?
  
  CSRF testing includes: 1) Verify token presence, 2) Test token validation, 3) Check token renewal, 4) Test request...
- How do you test password security?
  
  Password security testing: 1) Test password policies, 2) Check hashing implementation, 3) Verify password reset, 4)...
- What are approaches for testing data encryption?
  
  Encryption testing: 1) Verify data encryption, 2) Test key management, 3) Check encrypted storage, 4) Test encrypted...
- How do you test error handling for security?
  
  Security error testing: 1) Test error messages, 2) Check information disclosure, 3) Verify error logging, 4) Test...
Continuous Integration & Deployment
- How do you integrate Mocha tests into a CI/CD pipeline?
  
  Integration steps include: 1) Configure test scripts in package.json, 2) Set up test environment in CI, 3) Configure...
- What are best practices for running Mocha tests in CI?
  
  Best practices include: 1) Use --reporter for CI-friendly output, 2) Set appropriate timeouts, 3) Configure retry...
- How do you handle test environments in CI/CD?
  
  Environment handling: 1) Configure environment variables, 2) Set up test databases, 3) Manage service dependencies,...
- What is the role of test reporting in CI/CD?
  
  Test reporting involves: 1) Generate test results, 2) Create coverage reports, 3) Track test trends, 4) Identify...
- How do you handle test failures in CI/CD?
  
  Failure handling: 1) Configure retry mechanisms, 2) Set failure thresholds, 3) Generate detailed reports, 4) Notify...
- What are strategies for test parallelization in CI?
  
  Parallelization strategies: 1) Split test suites, 2) Use parallel runners, 3) Balance test distribution, 4) Handle...
- How do you manage test data in CI/CD?
  
  Test data management: 1) Use data fixtures, 2) Implement data seeding, 3) Handle cleanup, 4) Manage test databases,...
- What is the purpose of test coverage in CI/CD?
  
  Coverage purposes: 1) Verify test completeness, 2) Identify untested code, 3) Set quality gates, 4) Track testing...
- How do you optimize test execution in CI?
  
  Optimization strategies: 1) Implement caching, 2) Use test parallelization, 3) Optimize resource usage, 4) Minimize...
- What are common CI/CD pipeline configurations for Mocha?
  
  Common configurations: 1) Install dependencies, 2) Run linting, 3) Execute tests, 4) Generate reports, 5) Deploy on...
Reporter & Output
- What are the built-in reporters in Mocha?
  
  Built-in reporters include: 1) spec - hierarchical view, 2) dot - minimal dots output, 3) nyan - fun nyan cat...
- How do you configure reporters in Mocha?
  
  Reporter configuration: 1) Use --reporter flag in CLI, 2) Configure in mocha.opts, 3) Set in package.json, 4)...
- What is the spec reporter and when should it be used?
  
  Spec reporter: 1) Provides hierarchical view, 2) Shows nested describe blocks, 3) Indicates test status, 4) Displays...
- How do you handle test failure output?
  
  Failure output handling: 1) Display error messages, 2) Show stack traces, 3) Format error details, 4) Include test...
- What is the purpose of the JSON reporter?
  
  JSON reporter: 1) Machine-readable output, 2) CI/CD integration, 3) Custom processing, 4) Report generation, 5) Data...
- How do you customize test output format?
  
  Output customization: 1) Select appropriate reporter, 2) Configure reporter options, 3) Set output colors, 4) Format...
- What is the TAP reporter used for?
  
  TAP reporter: 1) Test Anything Protocol format, 2) Integration with TAP consumers, 3) Standard test output, 4) Tool...
- How do you enable multiple reporters?
  
  Multiple reporters: 1) Use reporter packages, 2) Configure output paths, 3) Specify reporter options, 4) Handle...
- What is the purpose of reporter options?
  
  Reporter options: 1) Customize output format, 2) Set output file paths, 3) Configure colors, 4) Control detail...
- How do you handle test duration reporting?
  
  Duration reporting: 1) Configure time display, 2) Set slow test threshold, 3) Show execution times, 4) Highlight...
Performance Testing
- What is performance testing in Mocha and why is it important?
  
  Performance testing involves: 1) Measuring test execution speed, 2) Monitoring resource usage, 3) Identifying...
- How do you measure test execution time in Mocha?
  
  Execution time measurement: 1) Use built-in reporters, 2) Implement custom timing, 3) Track individual test...
- What are common performance bottlenecks in Mocha tests?
  
  Common bottlenecks: 1) Slow test setup/teardown, 2) Inefficient assertions, 3) Synchronous operations, 4) Resource...
- How do you identify slow tests?
  
  Slow test identification: 1) Use --slow flag, 2) Monitor execution times, 3) Implement timing reporters, 4) Track...
- What is the impact of hooks on test performance?
  
  Hook impact: 1) Setup/teardown overhead, 2) Resource allocation, 3) Asynchronous operations, 4) Database operations,...
- How do you optimize test setup and teardown?
  
  Setup/teardown optimization: 1) Minimize operations, 2) Use efficient methods, 3) Share setup when possible, 4)...
- What role does async/await play in performance?
  
  Async/await impact: 1) Efficient async handling, 2) Reduced callback complexity, 3) Better error handling, 4)...
- How do you handle memory usage in tests?
  
  Memory management: 1) Monitor memory usage, 2) Clean up resources, 3) Prevent memory leaks, 4) Optimize object...
- What are strategies for test parallelization?
  
  Parallelization strategies: 1) Use multiple processes, 2) Split test suites, 3) Balance test distribution, 4) Handle...
- How do you monitor test performance?
  
  Performance monitoring: 1) Track execution metrics, 2) Use profiling tools, 3) Monitor resource usage, 4) Collect...

What is Mocha and what are its key features?

Mocha is a feature-rich JavaScript test framework running on Node.js and browser. Key features include: 1) Flexible test structure with describe/it blocks, 2) Support for asynchronous testing, 3) Multiple assertion library support, 4) Test hooks (before, after, etc.), 5) Rich reporting options, 6) Browser support, 7) Plugin architecture.

How do you set up Mocha in a project?

Setup involves: 1) Installing Mocha: npm install --save-dev mocha, 2) Adding test script to package.json: { 'scripts': { 'test': 'mocha' } }, 3) Creating test directory, 4) Choosing assertion library (e.g., Chai), 5) Creating test files with .test.js or .spec.js extension.

What are describe() and it() functions in Mocha?

describe() is used to group related tests (test suite), while it() defines individual test cases. Example: describe('Calculator', () => { it('should add numbers correctly', () => { /* test */ }); }). They help organize tests hierarchically and provide clear test structure.

How does Mocha handle asynchronous tests?

Mocha handles async testing through: 1) done callback parameter, 2) Returning promises, 3) async/await syntax. Example: it('async test', async () => { const result = await asyncOperation(); assert(result); }). Tests wait for async operations to complete.

What are hooks in Mocha and how are they used?

Mocha provides hooks: 1) before() - runs once before all tests, 2) beforeEach() - runs before each test, 3) after() - runs once after all tests, 4) afterEach() - runs after each test. Used for setup and cleanup operations. Example: beforeEach(() => { /* setup */ });

How do you use assertion libraries with Mocha?

Mocha works with various assertion libraries: 1) Node's assert module, 2) Chai for BDD/TDD assertions, 3) Should.js for BDD style, 4) Expect.js for expect() style. Example with Chai: const { expect } = require('chai'); expect(value).to.equal(expected);

What are the different reporting options in Mocha?

Mocha offers various reporters: 1) spec - hierarchical test results, 2) dot - minimal dots output, 3) nyan - fun nyan cat reporter, 4) json - JSON test results, 5) html - HTML test report. Select using --reporter option or configure in mocha.opts.

How do you skip or mark tests as pending in Mocha?

Tests can be skipped/pending using: 1) it.skip() - skip test, 2) describe.skip() - skip suite, 3) it() without callback - mark pending, 4) .only() - run only specific tests. Example: it.skip('test to skip', () => { /* test */ });

What are exclusive tests in Mocha?

Exclusive tests using .only(): 1) it.only() runs only that test, 2) describe.only() runs only that suite, 3) Multiple .only() creates subset of tests to run, 4) Useful for debugging specific tests. Example: it.only('exclusive test', () => { /* test */ });

How do you handle timeouts in Mocha tests?

Timeout handling: 1) Set suite timeout: this.timeout(ms), 2) Set test timeout: it('test', function(done) { this.timeout(ms); }), 3) Default is 2000ms, 4) Set to 0 to disable timeout, 5) Can be set globally or per test.

What assertion libraries can be used with Mocha?

Mocha supports multiple assertion libraries: 1) Node's built-in assert module, 2) Chai for BDD/TDD assertions, 3) Should.js for BDD style assertions, 4) Expect.js for expect() style assertions, 5) Better-assert for C-style assertions. Each offers different syntax and capabilities.

How do you use Chai assertions in Mocha?

Using Chai involves: 1) Installing: npm install chai, 2) Importing desired interface (expect, should, assert), 3) Writing assertions using chosen style, 4) Using chainable language constructs, 5) Handling async assertions. Example: const { expect } = require('chai'); expect(value).to.equal(expected);

What are the different assertion styles in Chai?

Chai offers three styles: 1) Assert - traditional TDD style (assert.equal()), 2) Expect - BDD style with expect() (expect().to), 3) Should - BDD style with should chaining (value.should). Each style has its own syntax and use cases.

How do you handle asynchronous assertions?

Async assertions handled through: 1) Using done callback, 2) Returning promises, 3) Async/await syntax, 4) Chai-as-promised for promise assertions, 5) Proper error handling. Example: it('async test', async () => { await expect(promise).to.be.fulfilled; });

What are the common assertion patterns in Mocha?

Common patterns include: 1) Equality checking (equal, strictEqual), 2) Type checking (typeOf, instanceOf), 3) Value comparison (greater, less), 4) Property checking (property, include), 5) Exception testing (throw). Use appropriate assertions for different scenarios.

How do you test exceptions with assertions?

Exception testing approaches: 1) expect(() => {}).to.throw(), 2) assert.throws(), 3) Testing specific error types, 4) Verifying error messages, 5) Handling async errors. Example: expect(() => fn()).to.throw(ErrorType, 'error message');

What are chainable assertions in Chai?

Chainable assertions allow: 1) Fluent interface with natural language, 2) Combining multiple checks, 3) Negating assertions with .not, 4) Adding semantic meaning, 5) Improving test readability. Example: expect(value).to.be.an('array').that.is.not.empty;

How do you test object properties?

Object property testing: 1) Check property existence, 2) Verify property values, 3) Test nested properties, 4) Compare object structures, 5) Check property types. Example: expect(obj).to.have.property('key').that.equals('value');

What are assertion plugins and how are they used?

Assertion plugins: 1) Extend assertion capabilities, 2) Add custom assertions, 3) Integrate with testing tools, 4) Provide domain-specific assertions, 5) Enhance assertion functionality. Example: chai-as-promised for promise assertions.

How do you handle deep equality assertions?

Deep equality testing: 1) Use deep.equal for objects/arrays, 2) Compare nested structures, 3) Handle circular references, 4) Check property order, 5) Consider type coercion. Example: expect(obj1).to.deep.equal(obj2);

What are the different types of hooks in Mocha?

Mocha provides four types of hooks: 1) before() - runs once before all tests, 2) beforeEach() - runs before each test, 3) after() - runs once after all tests, 4) afterEach() - runs after each test. Hooks help with setup and cleanup operations.

How do you handle asynchronous operations in hooks?

Async hooks can be handled through: 1) done callback, 2) returning promises, 3) async/await syntax, 4) proper error handling, 5) timeout management. Example: beforeEach(async () => { await setupDatabase(); });

What is the execution order of hooks in Mocha?

Hook execution order: 1) before() at suite level, 2) beforeEach() from outer to inner, 3) test execution, 4) afterEach() from inner to outer, 5) after() at suite level. Understanding order is crucial for proper setup/cleanup.

How do you share context between hooks and tests?

Context sharing methods: 1) Using this keyword, 2) Shared variables in closure, 3) Hook-specific context objects, 4) Global test context, 5) Proper scoping of shared resources. Example: beforeEach(function() { this.sharedData = 'test'; });

What is the purpose of describe blocks in test organization?

describe blocks serve to: 1) Group related tests, 2) Create test hierarchy, 3) Share setup/teardown code, 4) Organize test suites, 5) Provide context for tests. Helps maintain clear test structure.

How do you handle cleanup in hooks?

Cleanup handling: 1) Use afterEach/after hooks, 2) Clean shared resources, 3) Reset state between tests, 4) Handle async cleanup, 5) Ensure proper error handling. Important for test isolation.

What are root level hooks?

Root level hooks: 1) Apply to all test files, 2) Set up global before/after hooks, 3) Handle common setup/teardown, 4) Manage shared resources, 5) Configure test environment. Used for project-wide setup.

How do you handle errors in hooks?

Hook error handling: 1) Try-catch blocks in hooks, 2) Promise error handling, 3) Error reporting in hooks, 4) Cleanup after errors, 5) Proper test failure handling. Ensures reliable test execution.

What are best practices for hook usage?

Hook best practices: 1) Keep hooks focused, 2) Minimize hook complexity, 3) Clean up resources properly, 4) Handle async operations correctly, 5) Maintain hook independence. Improves test maintainability.

How do you handle timeouts in hooks?

Hook timeout handling: 1) Set hook-specific timeouts, 2) Configure global timeouts, 3) Handle async timeouts, 4) Manage long-running operations, 5) Proper timeout error handling. Example: before(function() { this.timeout(5000); });

What are the different ways to handle asynchronous tests in Mocha?

Mocha supports multiple async patterns: 1) Using done callback, 2) Returning promises, 3) async/await syntax, 4) Using setTimeout/setInterval, 5) Event-based async. Example: it('async test', (done) => { asyncOperation(() => { done(); }); });

How does the done callback work in Mocha?

done callback: 1) Signals test completion, 2) Must be called exactly once, 3) Can pass error as argument, 4) Has timeout protection, 5) Used for callback-style async code. Test fails if done isn't called or called multiple times.

How do you test promises in Mocha?

Promise testing: 1) Return promise from test, 2) Chain .then() and .catch(), 3) Use promise assertions, 4) Handle rejection cases, 5) Test promise states. Example: return Promise.resolve().then(result => assert(result));

How do you use async/await in Mocha tests?

async/await usage: 1) Mark test function as async, 2) Use await for async operations, 3) Handle errors with try/catch, 4) Chain multiple await calls, 5) Maintain proper error handling. Example: it('async test', async () => { const result = await asyncOp(); });

How do you handle timeouts in async tests?

Timeout handling: 1) Set test timeout with this.timeout(), 2) Configure global timeouts, 3) Handle slow tests appropriately, 4) Set different timeouts for different environments, 5) Proper error handling for timeouts.

What are common pitfalls in async testing?

Common pitfalls: 1) Forgetting to return promises, 2) Missing done() calls, 3) Multiple done() calls, 4) Improper error handling, 5) Race conditions. Understanding these helps write reliable async tests.

How do you test event emitters asynchronously?

Event testing: 1) Listen for events with done, 2) Set appropriate timeouts, 3) Verify event data, 4) Handle multiple events, 5) Test error events. Example: emitter.once('event', () => done());

What is the purpose of async hooks in Mocha?

Async hooks: 1) Setup async resources, 2) Clean up async operations, 3) Handle async dependencies, 4) Manage async state, 5) Ensure proper test isolation. Used for async setup/teardown.

How do you handle sequential async operations?

Sequential handling: 1) Chain promises properly, 2) Use async/await, 3) Maintain operation order, 4) Handle errors in sequence, 5) Verify sequential results. Ensures correct operation order.

What are best practices for async testing?

Best practices: 1) Always handle errors, 2) Set appropriate timeouts, 3) Clean up resources, 4) Avoid nested callbacks, 5) Use modern async patterns. Ensures reliable async tests.

What is the difference between mocks and stubs?

Key differences include: 1) Stubs provide canned answers to calls, 2) Mocks verify behavior and interactions, 3) Stubs don't typically fail tests, 4) Mocks can fail tests if expected behavior doesn't occur, 5) Stubs are simpler and used for state testing while mocks are used for behavior testing.

What mocking libraries can be used with Mocha?

Common mocking libraries: 1) Sinon.js for comprehensive mocking, 2) Jest mocks when using Jest, 3) testdouble.js for test doubles, 4) Proxyquire for module mocking, 5) Nock for HTTP mocking. Each has specific use cases and features.

How do you create a basic stub with Sinon?

Creating stubs with Sinon: 1) sinon.stub() creates stub function, 2) .returns() sets return value, 3) .throws() makes stub throw error, 4) .callsFake() provides implementation, 5) .resolves()/.rejects() for promises. Example: const stub = sinon.stub().returns('value');

What are spies and how are they used?

Spies are used to: 1) Track function calls, 2) Record arguments, 3) Check call count, 4) Verify call order, 5) Monitor return values. Example: const spy = sinon.spy(object, 'method'); Test wraps existing functions without changing behavior.

How do you mock HTTP requests?

HTTP mocking approaches: 1) Use Nock for HTTP mocks, 2) Mock fetch/axios globally, 3) Stub specific endpoints, 4) Mock response data, 5) Simulate network errors. Example: nock('http://api.example.com').get('/data').reply(200, { data: 'value' });

What is module mocking and how is it implemented?

Module mocking involves: 1) Using Proxyquire or similar tools, 2) Replacing module dependencies, 3) Mocking specific exports, 4) Maintaining module interface, 5) Handling module side effects. Helps isolate code under test.

How do you verify mock/stub calls?

Call verification includes: 1) Check call count with calledOnce/Twice, 2) Verify arguments with calledWith, 3) Check call order with calledBefore/After, 4) Verify call context with calledOn, 5) Assert on return values.

What are sandboxes in Sinon and why use them?

Sinon sandboxes: 1) Group mocks/stubs together, 2) Provide automatic cleanup, 3) Isolate test setup, 4) Prevent mock leakage, 5) Simplify test maintenance. Example: const sandbox = sinon.createSandbox(); sandbox.restore();

How do you handle mock cleanup?

Mock cleanup approaches: 1) Use afterEach hooks, 2) Implement sandbox restoration, 3) Reset individual mocks, 4) Clean up module mocks, 5) Restore original implementations. Prevents test interference.

What are fake timers and how are they used?

Fake timers: 1) Mock Date/setTimeout/setInterval, 2) Control time progression, 3) Test time-dependent code, 4) Simulate delays without waiting, 5) Handle timer cleanup. Example: sinon.useFakeTimers();

What are the best practices for organizing test files?

Best practices include: 1) Mirror source code structure, 2) Use consistent naming conventions (.test.js, .spec.js), 3) Group related tests together, 4) Maintain test independence, 5) Keep test files focused and manageable, 6) Use descriptive file names.

How should describe blocks be structured?

describe blocks should: 1) Group related test cases, 2) Follow logical hierarchy, 3) Use clear, descriptive names, 4) Maintain proper nesting levels, 5) Share common setup when appropriate. Example: describe('User Authentication', () => { describe('Login', () => {});

What are the guidelines for writing test descriptions?

Test descriptions should: 1) Be clear and specific, 2) Describe expected behavior, 3) Use consistent terminology, 4) Follow 'it should...' pattern, 5) Be readable as complete sentences. Example: it('should return error for invalid input')

How do you handle test dependencies?

Handle dependencies by: 1) Using before/beforeEach hooks, 2) Creating shared fixtures, 3) Implementing test helpers, 4) Managing shared state carefully, 5) Cleaning up after tests. Ensures test isolation.

What is the purpose of test hooks in organization?

Test hooks serve to: 1) Set up test prerequisites, 2) Clean up after tests, 3) Share common setup logic, 4) Manage test resources, 5) Maintain test isolation. Example: beforeEach(), afterEach() for setup/cleanup.

How should test utilities be organized?

Test utilities should be: 1) Placed in separate helper files, 2) Grouped by functionality, 3) Made reusable across tests, 4) Well-documented, 5) Easy to maintain. Helps reduce code duplication.

What is the role of test fixtures?

Test fixtures: 1) Provide test data, 2) Set up test environment, 3) Ensure consistent test state, 4) Reduce setup duplication, 5) Make tests maintainable. Example: JSON files with test data.

How do you maintain test independence?

Maintain independence by: 1) Cleaning up after each test, 2) Avoiding shared state, 3) Using fresh fixtures, 4) Isolating test environments, 5) Proper hook usage. Prevents test interference.

What are common test file naming conventions?

Common conventions: 1) .test.js suffix, 2) .spec.js suffix, 3) Match source file names, 4) Use descriptive prefixes, 5) Group related tests. Example: user.test.js for user.js tests.

How should test configurations be managed?

Config management: 1) Use .mocharc.js file, 2) Separate environment configs, 3) Manage test timeouts, 4) Set reporter options, 5) Handle CLI arguments. Ensures consistent test execution.

What factors affect test execution speed in Mocha?

Key factors include: 1) Number and complexity of tests, 2) Async operation handling, 3) Test setup/teardown overhead, 4) File I/O operations, 5) Database interactions, 6) Network requests, 7) Resource cleanup efficiency.

How can you measure test execution time?

Measuring methods: 1) Use --reporter spec for timing info, 2) Implement custom reporters for timing, 3) Use console.time/timeEnd, 4) Track slow tests with --slow flag, 5) Monitor hook execution time.

What are best practices for optimizing test setup?

Setup optimization: 1) Use beforeAll for one-time setup, 2) Minimize per-test setup, 3) Share setup when possible, 4) Cache test resources, 5) Use efficient data creation methods.

How do you identify slow tests?

Identification methods: 1) Use --slow flag to mark slow tests, 2) Implement timing reporters, 3) Monitor test duration, 4) Profile test execution, 5) Track resource usage. Example: mocha --slow 75.

What is the impact of hooks on test performance?

Hook impacts: 1) Setup/teardown overhead, 2) Resource allocation costs, 3) Database operation time, 4) File system operations, 5) Network request delays. Optimize hooks for better performance.

How can test parallelization improve performance?

Parallelization benefits: 1) Reduced total execution time, 2) Better resource utilization, 3) Concurrent test execution, 4) Improved CI/CD pipeline speed, 5) Efficient test distribution.

What is the role of timeouts in test performance?

Timeout considerations: 1) Default timeout settings, 2) Per-test timeouts, 3) Hook timeouts, 4) Async operation timing, 5) Timeout impact on test speed. Balance between reliability and speed.

How do you optimize async test execution?

Async optimization: 1) Use proper async patterns, 2) Avoid unnecessary waiting, 3) Implement efficient promises, 4) Handle concurrent operations, 5) Optimize async cleanup.

What impact does mocking have on performance?

Mocking impacts: 1) Mock creation overhead, 2) Stub implementation efficiency, 3) Mock cleanup costs, 4) Memory usage, 5) Mock verification time. Balance between isolation and performance.

How can test data management affect performance?

Data management impacts: 1) Data creation time, 2) Cleanup overhead, 3) Database operations, 4) Memory usage, 5) I/O operations. Optimize data handling for better performance.

What is integration testing and how does it differ from unit testing?

Integration testing involves: 1) Testing multiple components together, 2) Verifying component interactions, 3) Testing external dependencies, 4) End-to-end functionality verification, 5) Testing real subsystems. Unlike unit tests, integration tests focus on component interactions rather than isolated functionality.

How do you set up integration tests in Mocha?

Setup involves: 1) Configuring test environment, 2) Setting up test databases, 3) Managing external services, 4) Handling test data, 5) Configuring proper timeouts. Example: separate test configuration for integration tests.

What are common integration test patterns?

Common patterns include: 1) Database integration testing, 2) API endpoint testing, 3) Service integration testing, 4) External service testing, 5) Component interaction testing. Focus on testing integrated functionality.

How do you handle test data in integration tests?

Test data handling: 1) Use test databases, 2) Implement data seeding, 3) Clean up test data, 4) Manage test state, 5) Handle data dependencies. Ensures reliable test execution.

What are best practices for database integration testing?

Database testing practices: 1) Use separate test database, 2) Implement transactions, 3) Clean up after tests, 4) Handle migrations, 5) Manage connections efficiently. Ensures data integrity.

How do you test API endpoints?

API testing involves: 1) Making HTTP requests, 2) Verifying responses, 3) Testing error cases, 4) Checking headers/status codes, 5) Testing authentication. Example: using supertest or axios.

What are strategies for handling external services?

External service strategies: 1) Use test doubles when needed, 2) Configure test endpoints, 3) Handle authentication, 4) Manage service state, 5) Handle network issues.

How do you ensure test isolation in integration tests?

Test isolation methods: 1) Clean database between tests, 2) Reset service state, 3) Use transactions, 4) Implement proper teardown, 5) Handle shared resources.

What role do hooks play in integration testing?

Hooks are used for: 1) Setting up test environment, 2) Database preparation, 3) Service initialization, 4) Resource cleanup, 5) State management. Critical for test setup/teardown.

How do you handle asynchronous operations in integration tests?

Async handling includes: 1) Using async/await, 2) Proper timeout configuration, 3) Handling promises, 4) Managing concurrent operations, 5) Error handling.

What is security testing in Mocha and why is it important?

Security testing involves: 1) Testing authentication mechanisms, 2) Verifying authorization controls, 3) Testing input validation, 4) Checking data protection, 5) Testing against common vulnerabilities. Important for ensuring application security and protecting user data.

How do you test authentication in Mocha?

Authentication testing includes: 1) Testing login functionality, 2) Verifying token handling, 3) Testing session management, 4) Checking password policies, 5) Testing multi-factor authentication. Example: test invalid credentials, token expiration.

What are best practices for testing authorization?

Authorization testing practices: 1) Test role-based access, 2) Verify permission levels, 3) Check resource access, 4) Test access denial, 5) Verify resource isolation. Ensures proper access control.

How do you test input validation?

Input validation testing: 1) Test for XSS attacks, 2) Check SQL injection, 3) Validate data formats, 4) Test boundary conditions, 5) Check sanitization. Prevents malicious input.

What are common security test patterns?

Common patterns include: 1) Authentication testing, 2) Authorization checks, 3) Input validation, 4) Session management, 5) Data protection testing. Forms basis of security testing.

How do you test session management?

Session testing involves: 1) Test session creation, 2) Verify session expiration, 3) Check session isolation, 4) Test concurrent sessions, 5) Verify session invalidation.

What is CSRF testing and how is it implemented?

CSRF testing includes: 1) Verify token presence, 2) Test token validation, 3) Check token renewal, 4) Test request forgery scenarios, 5) Verify protection mechanisms.

How do you test password security?

Password security testing: 1) Test password policies, 2) Check hashing implementation, 3) Verify password reset, 4) Test password change, 5) Check against common vulnerabilities.

What are approaches for testing data encryption?

Encryption testing: 1) Verify data encryption, 2) Test key management, 3) Check encrypted storage, 4) Test encrypted transmission, 5) Verify decryption process.

How do you test error handling for security?

Security error testing: 1) Test error messages, 2) Check information disclosure, 3) Verify error logging, 4) Test error recovery, 5) Check security breach handling.

How do you integrate Mocha tests into a CI/CD pipeline?

Integration steps include: 1) Configure test scripts in package.json, 2) Set up test environment in CI, 3) Configure test runners, 4) Set up reporting, 5) Handle test failures. Example: npm test script in CI configuration.

What are best practices for running Mocha tests in CI?

Best practices include: 1) Use --reporter for CI-friendly output, 2) Set appropriate timeouts, 3) Configure retry mechanisms, 4) Handle test artifacts, 5) Implement proper error reporting.

How do you handle test environments in CI/CD?

Environment handling: 1) Configure environment variables, 2) Set up test databases, 3) Manage service dependencies, 4) Handle cleanup, 5) Isolate test environments for each build.

What is the role of test reporting in CI/CD?

Test reporting involves: 1) Generate test results, 2) Create coverage reports, 3) Track test trends, 4) Identify failures, 5) Provide build status feedback. Important for build decisions.

How do you handle test failures in CI/CD?

Failure handling: 1) Configure retry mechanisms, 2) Set failure thresholds, 3) Generate detailed reports, 4) Notify relevant teams, 5) Preserve failure artifacts for debugging.

What are strategies for test parallelization in CI?

Parallelization strategies: 1) Split test suites, 2) Use parallel runners, 3) Balance test distribution, 4) Handle resource conflicts, 5) Aggregate test results.

How do you manage test data in CI/CD?

Test data management: 1) Use data fixtures, 2) Implement data seeding, 3) Handle cleanup, 4) Manage test databases, 5) Ensure data isolation between builds.

What is the purpose of test coverage in CI/CD?

Coverage purposes: 1) Verify test completeness, 2) Identify untested code, 3) Set quality gates, 4) Track testing progress, 5) Guide test development.

How do you optimize test execution in CI?

Optimization strategies: 1) Implement caching, 2) Use test parallelization, 3) Optimize resource usage, 4) Minimize setup time, 5) Remove unnecessary tests.

What are common CI/CD pipeline configurations for Mocha?

Common configurations: 1) Install dependencies, 2) Run linting, 3) Execute tests, 4) Generate reports, 5) Deploy on success. Example using GitHub Actions or Jenkins.

What are the built-in reporters in Mocha?

Built-in reporters include: 1) spec - hierarchical view, 2) dot - minimal dots output, 3) nyan - fun nyan cat reporter, 4) tap - TAP output, 5) json - JSON format, 6) list - simple list, 7) min - minimalistic output.

How do you configure reporters in Mocha?

Reporter configuration: 1) Use --reporter flag in CLI, 2) Configure in mocha.opts, 3) Set in package.json, 4) Specify reporter options, 5) Enable multiple reporters. Example: mocha --reporter spec

What is the spec reporter and when should it be used?

Spec reporter: 1) Provides hierarchical view, 2) Shows nested describe blocks, 3) Indicates test status, 4) Displays execution time, 5) Best for development and debugging. Default reporter for readability.

How do you handle test failure output?

Failure output handling: 1) Display error messages, 2) Show stack traces, 3) Format error details, 4) Include test context, 5) Highlight failure location. Important for debugging.

What is the purpose of the JSON reporter?

JSON reporter: 1) Machine-readable output, 2) CI/CD integration, 3) Custom processing, 4) Report generation, 5) Data analysis. Useful for automated processing.

How do you customize test output format?

Output customization: 1) Select appropriate reporter, 2) Configure reporter options, 3) Set output colors, 4) Format error messages, 5) Control detail level.

What is the TAP reporter used for?

TAP reporter: 1) Test Anything Protocol format, 2) Integration with TAP consumers, 3) Standard test output, 4) Tool compatibility, 5) Pipeline integration. Used for tool interoperability.

How do you enable multiple reporters?

Multiple reporters: 1) Use reporter packages, 2) Configure output paths, 3) Specify reporter options, 4) Handle different formats, 5) Manage output files. Useful for different needs.

What is the purpose of reporter options?

Reporter options: 1) Customize output format, 2) Set output file paths, 3) Configure colors, 4) Control detail level, 5) Set specific behaviors. Enables reporter customization.

How do you handle test duration reporting?

Duration reporting: 1) Configure time display, 2) Set slow test threshold, 3) Show execution times, 4) Highlight slow tests, 5) Track test performance. Important for optimization.

What is performance testing in Mocha and why is it important?

Performance testing involves: 1) Measuring test execution speed, 2) Monitoring resource usage, 3) Identifying bottlenecks, 4) Optimizing test runs, 5) Tracking performance metrics. Important for maintaining efficient test suites.

How do you measure test execution time in Mocha?

Execution time measurement: 1) Use built-in reporters, 2) Implement custom timing, 3) Track individual test durations, 4) Monitor suite execution, 5) Use performance APIs. Example: console.time() or process.hrtime().

What are common performance bottlenecks in Mocha tests?

Common bottlenecks: 1) Slow test setup/teardown, 2) Inefficient assertions, 3) Synchronous operations, 4) Resource leaks, 5) Poor test isolation. Understanding helps optimization.

How do you identify slow tests?

Slow test identification: 1) Use --slow flag, 2) Monitor execution times, 3) Implement timing reporters, 4) Track test duration, 5) Profile test execution. Example: mocha --slow 75.

What is the impact of hooks on test performance?

Hook impact: 1) Setup/teardown overhead, 2) Resource allocation, 3) Asynchronous operations, 4) Database operations, 5) File system access. Optimize hooks for better performance.

How do you optimize test setup and teardown?

Setup/teardown optimization: 1) Minimize operations, 2) Use efficient methods, 3) Share setup when possible, 4) Implement proper cleanup, 5) Cache resources. Reduces overhead.

What role does async/await play in performance?

Async/await impact: 1) Efficient async handling, 2) Reduced callback complexity, 3) Better error handling, 4) Improved readability, 5) Sequential execution control. Important for async operations.

How do you handle memory usage in tests?

Memory management: 1) Monitor memory usage, 2) Clean up resources, 3) Prevent memory leaks, 4) Optimize object creation, 5) Handle large datasets. Important for stability.

What are strategies for test parallelization?

Parallelization strategies: 1) Use multiple processes, 2) Split test suites, 3) Balance test distribution, 4) Handle shared resources, 5) Manage concurrency. Improves execution speed.

How do you monitor test performance?

Performance monitoring: 1) Track execution metrics, 2) Use profiling tools, 3) Monitor resource usage, 4) Collect timing data, 5) Analyze bottlenecks. Important for optimization.

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Mocha Interview Questions Your Guide to Success

mocha

What is Mocha and what are its key features?

How do you set up Mocha in a project?

What are describe() and it() functions in Mocha?

How does Mocha handle asynchronous tests?

What are hooks in Mocha and how are they used?

How do you use assertion libraries with Mocha?

What are the different reporting options in Mocha?

How do you skip or mark tests as pending in Mocha?

What are exclusive tests in Mocha?

How do you handle timeouts in Mocha tests?

What assertion libraries can be used with Mocha?

How do you use Chai assertions in Mocha?

What are the different assertion styles in Chai?

How do you handle asynchronous assertions?

What are the common assertion patterns in Mocha?

How do you test exceptions with assertions?

What are chainable assertions in Chai?

How do you test object properties?

What are assertion plugins and how are they used?

How do you handle deep equality assertions?

What are the different types of hooks in Mocha?

How do you handle asynchronous operations in hooks?

What is the execution order of hooks in Mocha?

How do you share context between hooks and tests?

What is the purpose of describe blocks in test organization?

How do you handle cleanup in hooks?

What are root level hooks?

How do you handle errors in hooks?

What are best practices for hook usage?

How do you handle timeouts in hooks?

What are the different ways to handle asynchronous tests in Mocha?

How does the done callback work in Mocha?

How do you test promises in Mocha?

How do you use async/await in Mocha tests?

How do you handle timeouts in async tests?

What are common pitfalls in async testing?

How do you test event emitters asynchronously?

What is the purpose of async hooks in Mocha?

How do you handle sequential async operations?

What are best practices for async testing?

What is the difference between mocks and stubs?

What mocking libraries can be used with Mocha?

How do you create a basic stub with Sinon?

What are spies and how are they used?

How do you mock HTTP requests?

What is module mocking and how is it implemented?

How do you verify mock/stub calls?

What are sandboxes in Sinon and why use them?

How do you handle mock cleanup?

What are fake timers and how are they used?

What are the best practices for organizing test files?

How should describe blocks be structured?

What are the guidelines for writing test descriptions?

How do you handle test dependencies?

What is the purpose of test hooks in organization?

How should test utilities be organized?

What is the role of test fixtures?

How do you maintain test independence?

What are common test file naming conventions?

How should test configurations be managed?

What factors affect test execution speed in Mocha?

How can you measure test execution time?

What are best practices for optimizing test setup?

How do you identify slow tests?

What is the impact of hooks on test performance?

How can test parallelization improve performance?

What is the role of timeouts in test performance?

How do you optimize async test execution?

What impact does mocking have on performance?

How can test data management affect performance?

What is integration testing and how does it differ from unit testing?

How do you set up integration tests in Mocha?