Troubleshooting: Why Angular Tests Fail with ng e2e but Pass with protractor conf.js

Описание: Discover the reasons behind Angular end-to-end (E2E) test failures with `ng e2e`, while tests succeed when using Protractor directly. Learn how to address these issues effectively.
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Understanding Angular E2E Test Failures: ng e2e vs. protractor conf.js

When working with Angular applications, automated testing is key to ensuring that your app performs as expected. However, you might run into situations where your end-to-end (E2E) tests fail when running them using the Angular command ng e2e, while the same tests pass flawlessly when using the Protractor command protractor conf.js. This predicament can be puzzling and frustrating, especially for developers striving for robust automation testing. In this post, we will explore the reasons behind this behavior and how to resolve it.

The Problem: Discrepancy in Test Results

When you execute the command ng e2e, Angular first serves your application before running the end-to-end tests. On the other hand, running Protractor with protractor conf.js does not require serving the application beforehand, leading to different behaviors and outcomes during testing.

Here’s a quick breakdown of the issue:

Command: ng e2e

Behavior: Serves the app first, then runs E2E tests.

Outcome: All tests fail.

Command: protractor conf.js

Behavior: Directly runs the Protractor tests without serving the app.

Outcome: All tests pass.

Resolving the Issue: Possible Solutions

1. Ensure the Angular App is Properly Served

When using ng e2e, it's important that your application is correctly served before tests are executed. If there are issues with serving the app (such as network problems or compilation errors), the tests will fail. Check your server logs for any potential errors.

2. Increase Timeout for Test Steps

One apparent issue in the Protractor test code shared above is the use of setTimeout with a prolonged delay (30000 milliseconds). This could indicate that your tests may require additional time to interact with the application. Here are some suggestions to improve the timing and flow of your tests:

Use Protractor's built-in wait mechanisms: Rather than using setTimeout, leverage Protractor’s native waiting functions to ensure elements are present and ready for interaction. For instance, replacing setTimeout with browser.sleep() or ExpectedConditions can help manage asynchronous test flows more effectively.

Example of replacing setTimeout:

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3. Check for Dependencies on Network or External APIs

If your tests interact with external APIs or require network access, make sure that these services are reachable when running ng e2e. Network issues can cause your tests to fail unexpectedly during execution.

4. Review Angular Configuration Settings

It’s also wise to review your Angular and Protractor configuration files for any discrepancies. Ensure that the configurations set in protractor.conf.js align with those required for ng e2e. Misconfigurations can lead to inconsistencies in the testing outcome.

5. Debugging the Tests

Utilizing debugging tools can help you ascertain where things are going wrong. You can run your Protractor tests with a debugging flag or verbose logging to get insights into the test flow and potential failures.

Conclusion

While encountering the error of failing Angular E2E tests when using ng e2e can be frustrating, understanding the differences in behavior between it and protractor conf.js allows you to pinpoint where things may be going wrong. By serving the application properly, leveraging Protractor's built-in functions, and ensuring that all configurations and dependencies are correctly set up, you’ll be well on your way to achieving reliable test results.

If you have further questions or need assistance, feel free to dive into the comments below or reach out to the community of Angular developers fo