feat(compiler): Add fixedOrder option to expectDiagnostics

[harlanenciso112]

Resolves #5818

Description

Added a new fixedOrder option to the expectDiagnostics function that allows testing diagnostics regardless of the order they appear in. This makes tests more resilient to code changes that might alter diagnostic order without changing the actual diagnostic content.

Problem

Tests that use expectDiagnostics would fail when diagnostic order changes, even though this should not be considered a breaking change. Library test authors had to create wrappers to pre-sort diagnostics collections.

Solution

• Added fixedOrder option to expectDiagnostics (defaults to true for backward compatibility)
• When fixedOrder: false, diagnostics can match in any order
• Maintains existing behavior when using the default options

Testing

All existing tests pass, confirming that backward compatibility is maintained.

Changes

• Minor: Added new option to existing function

[harlanenciso112]

@microsoft-github-policy-service agree

[timotheeguerin]

we use something else than changeset for this repo called chronus. Either follow the comment that should get added soon or use pnpm chronus add

[github-actions]

❌ There is undocummented changes. Run chronus add to add a changeset or click here.

The following packages have changes but are not documented.

• ❌@typespec/compiler

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[timotheeguerin]

The approach we decided here was to sort the diagnostics so they diff can still be used.
The reason I didn't want to add this at it was was exactly because it made the test experience worse when it didn't find the match and in general it was bad pattern to have multiple diagnostics tested at the same time. We decided that sorting the diagnositcs and expectation would still provide the benefits while not loosing the diff

[timotheeguerin]

Thanks for the contribution, I think unfortunately we'd prefer to go with a bit of a different approach for this.

Have you found yourself needing this feature?

[harlanenciso112]

Thanks for your feedback @timotheeguerin!

I understand your preference for sorting the diagnostics instead of the fixedOrder approach. That makes sense - preserving the diff functionality would provide better feedback when tests fail.

I implemented this feature based on the issue description which suggested adding a fixedOrder option. I haven't personally needed this feature, but was working on resolving the open issue.

Regarding the changeset, I tried to create one manually but wasn't familiar with Chronus. I'll try using pnpm chronus add as you suggested.

Would you like me to:

1. Close this PR and create a new one with the sorting approach instead?
2. Modify this PR to implement sorting of diagnostics?

Thanks for the guidance!

[timotheeguerin]

You can keep modifying this PR, and yeah sorry about the issue description we have not been doing a good job of relecting our internal discussions on them

For chronus you can also just use that comment which has a link to add it #7453 (comment)