test('user authentication', () => {
 const user = authenticateUser();
 console.log(user); // Basic logging
 expect(user.isAuthenticated).toBe(true);
});

Use structured logging:

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test('user authentication', () => {
  const user = authenticateUser();
  console.log({
    state: 'Pre-Authentication',
    userDetails: user,
    timestamp: new Date().toISOString()
  });
  expect(user.isAuthenticated).toBe(true);
});

![An abstract representation of flowing data streams in space with interconnected nodes and pathways. Colors: bright orange and blue gradients against dark background. Camera angle: Dynamic diagonal perspective. high-quality ultra-realistic cinematic 8K UHD high resolution sharp and detail](/image_generation/tillitsdone_Jest_Tips-and-tricks_topics_find_How-to-Debug-Jest-Tests-Effectivelycontent_1732733162083_1.jpeg "An abstract representation of flowing data streams in space with interconnected nodes and pathways. Colors: bright orange and blue gradients against dark background. Camera angle: Dynamic diagonal perspective. high-quality ultra-realistic cinematic 8K UHD high resolution sharp and detail")

Jest-Specific Debugging Commands

The .only and .skip modifiers are invaluable for focusing on specific tests:

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describe.only('critical auth flow', () => {
  test('should validate user credentials', () => {
    // Your test code
  });
});
Using Node.js Debugger

Add debugger statements in your tests and run Jest in debug mode:

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test('complex data transformation', () => {
  const inputData = fetchTestData();
  debugger; // Execution will pause here
  const transformed = transformData(inputData);
  expect(transformed).toMatchSnapshot();
});

Run with: node --inspect-brk node_modules/.bin/jest --runInBand

![A futuristic space station control room with holographic displays and clean geometric patterns. Colors: creamy whites and bright blue accents. Camera angle: Wide-angle front view. high-quality ultra-realistic cinematic 8K UHD high resolution sharp and detail](/image_generation/tillitsdone_Jest_Tips-and-tricks_topics_find_How-to-Debug-Jest-Tests-Effectivelycontent_1732733162083_2.jpeg "A futuristic space station control room with holographic displays and clean geometric patterns. Colors: creamy whites and bright blue accents. Camera angle: Wide-angle front view. high-quality ultra-realistic cinematic 8K UHD high resolution sharp and detail")

Test Environment Setup

Properly configured setupFiles can prevent many debugging headaches:

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// jest.setup.js
global.setupTestEnvironment = () => {
  // Clear mocks, set timezone, etc.
};

beforeEach(() => {
  setupTestEnvironment();
});

Remember to add detailed error messages in your custom matchers and assertions - they're invaluable when tests fail.

![An abstract ocean scene with geometric waves and flowing patterns representing data flow. Colors: silver and bright blue tones with white highlights. Camera angle: Low angle looking up through the waves. high-quality ultra-realistic cinematic 8K UHD high resolution sharp and detail](/image_generation/tillitsdone_Jest_Tips-and-tricks_topics_find_How-to-Debug-Jest-Tests-Effectivelycontent_1732733162083_3.jpeg "An abstract ocean scene with geometric waves and flowing patterns representing data flow. Colors: silver and bright blue tones with white highlights. Camera angle: Low angle looking up through the waves. high-quality ultra-realistic cinematic 8K UHD high resolution sharp and detail")

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