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Вивчайте Running Tests and Reading Results | Writing and Running Tests Effectively
Testing JavaScript Code

bookRunning Tests and Reading Results

To run your tests using Jest, you typically use the jest command in your terminal. If you have installed Jest locally in your project, you can run all tests by typing npx jest or by using a script like npm test if your package.json is set up for it. When you execute this command, Jest searches for files with names like *.test.js or *.spec.js and runs the test cases defined inside them.

The output from Jest gives you a clear summary of your test results. Each test will show either a green checkmark or a red "x" next to its name. A green checkmark means the test has passed, while a red "x" signals a failure. If a test fails, Jest displays the error message, the expected and received values, and a stack trace pointing to the line where the failure occurred. This detailed information helps you quickly identify what went wrong and where in your code the problem exists.

Sometimes, you might see a yellow dot or a note about skipped tests. Skipped tests are not run, and Jest will indicate this clearly in the summary. At the end of the output, Jest provides a summary line showing the total number of tests run, how many passed, failed, or were skipped.

When interpreting the output, pay close attention to the error messages and stack traces. They often point directly to the source of the problem, such as a mismatch between expected and actual results or an uncaught exception. If you see a test fail, look for the following:

  • The name of the failed test;
  • The specific error message;
  • The line number or file where the failure occurred;
  • Any difference shown between expected and received values.

If you encounter a test that keeps failing, double-check your code and the test itself. Make sure the test is written correctly and that your code produces the expected output. Sometimes, typos or incorrect assumptions about the code's behavior can lead to failures. If the error message is unclear, try simplifying the test or adding console.log statements to inspect values during the test run.

Understanding the output and using it to guide your debugging process will make you more efficient at fixing issues and maintaining your test suite.

1. What does a green checkmark typically indicate in Jest's test output?

2. If a test fails in Jest, what information is usually provided in the output?

question mark

What does a green checkmark typically indicate in Jest's test output?

Select the correct answer

question mark

If a test fails in Jest, what information is usually provided in the output?

Select the correct answer

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bookRunning Tests and Reading Results

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To run your tests using Jest, you typically use the jest command in your terminal. If you have installed Jest locally in your project, you can run all tests by typing npx jest or by using a script like npm test if your package.json is set up for it. When you execute this command, Jest searches for files with names like *.test.js or *.spec.js and runs the test cases defined inside them.

The output from Jest gives you a clear summary of your test results. Each test will show either a green checkmark or a red "x" next to its name. A green checkmark means the test has passed, while a red "x" signals a failure. If a test fails, Jest displays the error message, the expected and received values, and a stack trace pointing to the line where the failure occurred. This detailed information helps you quickly identify what went wrong and where in your code the problem exists.

Sometimes, you might see a yellow dot or a note about skipped tests. Skipped tests are not run, and Jest will indicate this clearly in the summary. At the end of the output, Jest provides a summary line showing the total number of tests run, how many passed, failed, or were skipped.

When interpreting the output, pay close attention to the error messages and stack traces. They often point directly to the source of the problem, such as a mismatch between expected and actual results or an uncaught exception. If you see a test fail, look for the following:

  • The name of the failed test;
  • The specific error message;
  • The line number or file where the failure occurred;
  • Any difference shown between expected and received values.

If you encounter a test that keeps failing, double-check your code and the test itself. Make sure the test is written correctly and that your code produces the expected output. Sometimes, typos or incorrect assumptions about the code's behavior can lead to failures. If the error message is unclear, try simplifying the test or adding console.log statements to inspect values during the test run.

Understanding the output and using it to guide your debugging process will make you more efficient at fixing issues and maintaining your test suite.

1. What does a green checkmark typically indicate in Jest's test output?

2. If a test fails in Jest, what information is usually provided in the output?

question mark

What does a green checkmark typically indicate in Jest's test output?

Select the correct answer

question mark

If a test fails in Jest, what information is usually provided in the output?

Select the correct answer

Все було зрозуміло?

Як ми можемо покращити це?

Дякуємо за ваш відгук!

Секція 2. Розділ 1
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