fix(test_core): fix writeCoverage to handle a null hit map

[felangel]

• fix(test_core): fix writeCoverage to handle a null hit map
  • closes coverage breaks with @Tag in v1.27.0 #2562

---

• I’ve reviewed the contributor guide and applied the relevant portions to this PR.

Contribution guidelines:

• See our contributor guide for general expectations for PRs.
• Larger or significant changes should be discussed in an issue before creating a PR.
• Contributions to our repos should follow the Dart style guide and use dart format.
• Most changes should add an entry to the changelog and may need to rev the pubspec package version.
• Changes to packages require corresponding tests.

Many Dart repos have a weekly cadence for reviewing PRs - please allow for some latency before initial review feedback.

Note: The Dart team is trialing Gemini Code Assist. Don't take its comments as final Dart team feedback. Use the suggestions if they're helpful; otherwise, wait for a human reviewer.

[github-actions]

PR Health

Changelog Entry ✔️

Package	Changed Files

Changes to files need to be accounted for in their respective changelogs.

This check can be disabled by tagging the PR with skip-changelog-check.

[felangel]

@kevmoo looks like I needed to also bump the version in pkg:test since it was using an exact version. Let me know if there's anything else I need to adjust, thanks!

[github-actions]

Package publishing

Package	Version	Status	Publish tag (post-merge)
package:checks	0.3.2-wip	WIP (no publish necessary)
package:fake_async	1.3.3	already published at pub.dev
package:matcher	0.12.18-wip	WIP (no publish necessary)
package:test	1.27.1-wip	WIP (no publish necessary)
package:test_api	0.7.8	already published at pub.dev
package:test_core	0.6.14	ready to publish	test_core-v0.6.14
package:test_descriptor	2.0.2	already published at pub.dev
package:test_process	2.1.1	already published at pub.dev

Documentation at https://github.com/dart-lang/ecosystem/wiki/Publishing-automation.

[kevmoo]

Awesome!

[kevmoo]

I'd like @liamappelbe to double check

[felangel]

I'd like @liamappelbe to double check

Sounds good. I also verified the fix locally 👍