36 lines
1.6 KiB
Markdown
36 lines
1.6 KiB
Markdown
---
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title: >
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Tests are living documentation
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pubDate: 2022-12-30
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permalink: >-
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daily/2022/12/30/tests-are-living-documentation
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tags:
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- testing
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---
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Today I was working on a project and made a one-line change that updated a single value within an API response.
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Unexpectedly, it caused a test to fail. The API response returned a 500 status code instead of the expected 201 code.
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I reverted the change locally and ensured that the test passed again, so I knew it was causing the failure.
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## Fixing the failure
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The change was removing a hard-coded part of a URL to a dynamic one, using Drupal's `Settings` class.
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I was retrieving a value from it, but as there was no value being set within the test, it was returning a null value and causing the 500 error code.
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## How does the Settings class work?
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To fix the test failure, I needed to learn how to set a Settings value within a test.
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To do this, I looked for and found the test for the Settings class itself. I saw how it was being set there, did the same in my test, fixed the failure and got my test passing again.
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## Tests are living documentation
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As well as verifying things work when they are written, tests also act as long-term documentation. They can be run at any point to ensure that they still pass and are a reference to other developers on how the code should work.
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Rather than a Confluence page, a README file or code comments which can become out of date, if a test becomes outdated, it will fail and make developers aware, as well as break any CI pipeline that it runs in.
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By writing tests, you're ensuring that your code works as expected and documenting it at the same time.
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