Write tests for module diagnostic

[sheremet-va]

There is a forgotten test in test/unit: https://github.com/vitest-dev/vitest/blob/main/test/unit/test/module-diagnostic.test.ts

[eliottreich]

Hi, is this still available for an external contributor? I can add focused tests for the module-diagnostic behavior in the existing test/unit/test/module-diagnostic.test.ts file, following the surrounding test patterns and keeping the PR limited to the forgotten coverage.

[beanscg]

Bean Labs did a read-only module-diagnostic pass. packages/vitest/src/node/module-diagnostic.ts already has separate logic for collecting module durations and source module locations, including import/export parsing and SSR transform import mapping.

For "tests for module diagnostic", I would split fixtures by behavior: one for duplicate imports showing only one non-zero timing, one for untracked modules, and one for sourcemap mapping from transformed SSR imports back to original import locations.

No PR opened from this pass.