Fix the Test in async.spec.js

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Introduction

In this project, you will learn how to fix an issue in the async.spec.js file within the vue-router-3.0.1 project. The async.spec.js file contains a test case that is not correctly detecting an error, and your task is to modify the code to ensure the test passes as expected.

👀 Preview

Message:
    Expected $.length = 3 to equal 5.
    Expected $[3] = undefined to equal 4.
    Expected $[4] = undefined to equal 5.

🎯 Tasks

In this project, you will learn:

  • How to locate and modify the async.spec.js file in the vue-router-3.0.1 project
  • How to understand the issue with the existing test case
  • How to implement the necessary changes to fix the test case

🏆 Achievements

After completing this project, you will be able to:

  • Identify and fix issues in unit tests
  • Work with asynchronous code and the runQueue utility function
  • Apply techniques for debugging and troubleshooting test cases

Skills Graph

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Fix the Test in async.spec.js

To get started, we can see the vue-router-3.0.1 folder in the left directory of the editor.

In this step, you will learn how to fix the issue in the async.spec.js file in the vue-router-3.0.1 project.

  1. Open the vue-router-3.0.1/test/unit/specs/async.spec.js file.
  2. Locate the it("should work", (done) => { ... }) block.
  3. Change const queue = [1, 2, 3, 4, 5].map to const queue = [1, 2, 3].map to make it easier for us to test.
const queue = [1, 2, 3].map((i) => (next) => {
  // ...
});
  1. Open the vue-router-3.0.1 directory in the terminal.
  2. Run the command npm install to install the dependencies. This process might take a while, please be patient. (If it gets stuck for a long time, please press Ctrl+C to terminate the process and then run this command again.)
  3. After successfully installing all the dependencies, run the unit test by executing the command npm run test:unit in the terminal. Before the fix, you'll notice that the above test script didn't detect any errors. (In the above code, the value of calls is [1, 2, 3] which is not equal to [1, 2, 3, 4, 5]).
  4. To fix the above issue, let's go ahead and change inside the vue-router-3.0.1/test/unit/specs/async.spec.js file to the following code:
const queue = [1, 2, 3].map((i) => (next) => {
  calls.push(i);
  setTimeout(next, 0);
});

The change here is that we changed setTimeout(done, 0) to setTimeout(next, 0) making the function not jump right out.

Run the Tests

In this step, you will rebuild the vue-router-3.0.1 project and test the fixed effect.

  1. Re-execute the npm run test:unit command to run the unit tests.
  2. After the fix, you should see the following output:
Message:
    Expected $.length = 3 to equal 5.
    Expected $[3] = undefined to equal 4.
    Expected $[4] = undefined to equal 5.

This indicates that the async.spec.js test has been successfully fixed.

✨ Check Solution and Practice

Summary

Congratulations! You have completed this project. You can practice more labs in LabEx to improve your skills.

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