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Feat: add linting rule for before/beforeEach just like the async test rule #151

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merged 5 commits into from Apr 12, 2024

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Arcturus5404
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@Arcturus5404 Arcturus5404 commented Mar 1, 2024

PR for adding linting rules to the before and beforeEach. Having an async in the beforeEach and before can introduce unexpected behaviour, where the async process is not finished yet before the test runs. This can cause a test to be flaky. This rule will mark it as an error.

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CLAassistant commented Mar 1, 2024

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@Arcturus5404 Arcturus5404 marked this pull request as draft March 2, 2024 11:30
@Arcturus5404 Arcturus5404 marked this pull request as ready for review March 2, 2024 11:30
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Hi @Arcturus5404. Thank you for opening a PR! Can you please fill out the PR description to give reviewers better idea of what you are trying to accomplish with this contribution?

@@ -0,0 +1,52 @@
# Prevent using async/await in Cypress test cases (no-async-tests)

Cypress before that return a promise will cause tests to prematurely start, can cause unexpected behavior. An `async` function returns a promise under the hood, so a before using an `async` function might also error.
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are we sure this is always the case? This might be true for certain commands but I don't think generally this applies.

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I do not know if this is always true, I guess the cypress team knows this better than me. I noticed that the test method was already being executed while the before was still in progress

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interesting. I don't think I have run into this but I will take your word for it. Knowing how mocha hooks process and how we integrate with them, I can absolutely see this being true

docs/rules/no-async-before.md Outdated Show resolved Hide resolved
docs/rules/no-async-before.md Outdated Show resolved Hide resolved
@@ -36,6 +36,7 @@ You can add rules:
"cypress/assertion-before-screenshot": "warn",
"cypress/no-force": "warn",
"cypress/no-async-tests": "error",
"cypress/no-async-before": "error",
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Does this issue also occur in after/afterEach lifecycle hooks? Maybe no-async-hooks might be a better rule, if this is the case.

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I guess so, but I am not sure they will cause a problem. It might has the same potential to break your testcase. Should the new hook rule also include the test rule? one to rule them all?

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I do know that in before and beforeEach the async code might actually break the test, because of the dependency. But there might not be a problem as such in the after because of race conditions

Arcturus5404 and others added 2 commits April 3, 2024 08:38
Co-authored-by: Bill Glesias <bglesias@gmail.com>
Co-authored-by: Bill Glesias <bglesias@gmail.com>

## When Not To Use It

If there are genuine use-cases for using `async/await` in your before then you may not want to include this rule (or at least demote it to a warning).
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Suggested change
If there are genuine use-cases for using `async/await` in your before then you may not want to include this rule (or at least demote it to a warning).
If there are genuine use-cases for using `async/await` in your `before/beforeEach` function callback, then you may not want to include this rule (or at least demote it to a warning).

@AtofStryker AtofStryker merged commit 8628331 into cypress-io:master Apr 12, 2024
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I think that will be fine to just have the release triggered when the other things merge

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🎉 This PR is included in version 2.15.2 🎉

The release is available on:

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7 participants