feat(vitest): recognize __mocks__ specifiers as virtual#265
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BartWaardenburg merged 1 commit intofallow-rs:mainfrom May 3, 2026
Merged
feat(vitest): recognize __mocks__ specifiers as virtual#265BartWaardenburg merged 1 commit intofallow-rs:mainfrom
BartWaardenburg merged 1 commit intofallow-rs:mainfrom
Conversation
Vitest's manual-mock convention places mock factories at
`<package>/__mocks__/<module>.ts` and triggers them via
`vi.mock('<module>')`. Some test setups also import directly from
`@<scope>/__mocks__` paths via package.json `imports` aliases or
workspace virtual paths:
import { mockS3Send } from '@aws-sdk/__mocks__';
Fallow flags these as `unlisted-dep`, and the auto-fix suggests
'install this package' — but `@aws-sdk/__mocks__`,
`@sentry/__mocks__`, `@supabase/__mocks__` etc. do not exist on
npm.
Adds a sibling abstraction to the existing `virtual_module_prefixes`
(prefix-based matching used by Nuxt etc.):
- New `Plugin` trait method `virtual_package_suffixes() -> &[&'static str]`
with default `&[]`, propagated through `AggregatedPluginResult`.
- `VitestPlugin` returns `&["/__mocks__"]`.
- `find_unlisted_dependencies` skips any extracted `package_name`
ending with a registered suffix.
- `run_plugins` merges `virtual_package_suffixes` from per-workspace
plugin runs into the root `AggregatedPluginResult`, mirroring the
existing merge for `virtual_module_prefixes` and
`generated_import_patterns`. Without this, when vitest is only in a
workspace's `package.json` (not the root), the suffix gets registered
locally and dropped before the analyzer reads it.
Tests:
- 5 unit tests in `vitest.rs` and `unused_deps_tests` covering
scoped (`@aws-sdk/__mocks__`), unscoped (`some-pkg/__mocks__`),
and non-mocks specifiers.
- Registry test asserting vitest contributes the suffix.
- 2 integration tests with fixtures: `vitest-mocks-virtual`
(single-package, vitest at root) and `vitest-mocks-workspace`
(monorepo, vitest only in a workspace's package.json) — the second
fixture reproduces the workspace-aggregation case the unit tests
alone cannot catch.
BartWaardenburg
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May 3, 2026
Three follow-ups surfaced during pre-ship review of #263 and #265: 1. #263 added five tests for the Next.js dynamic-import re-export fix. Four are regression-strength but `dynamic_import_named_without_matching_export_still_flagged` is coverage-adjacent: the wrapper exports `Bar` and the duplicate detection looks for `Foo` between two unrelated modules, so the wrapper's `matches_export` check is never on the path that decides the test outcome. Removing the Named branch of `matches_export` does not make this test fail. Add a true regression test (`dynamic_import_named_mismatched_with_wrapper_export_still_flagged`) where the wrapper exports `Foo` AND dynamically imports a different name `Bar` from source, so without the matches_export Named branch the wrapper would be registered as a re-export edge and the (source, wrapper) `Foo` duplicate would be silently suppressed. Empirically verified: removing the Named branch makes this test fail and leaves the other four passing. 2. #265 added `Plugin::virtual_package_suffixes()` but only via an explicit `impl Plugin for VitestPlugin` block. The three `define_plugin!` macro variants in `plugins/mod.rs` still listed `virtual_module_prefixes` without a peer entry for the new field, so a future plugin author using the macro would have no path to declare suffixes. Extend all three variants to accept `virtual_package_suffixes:` and add a synthetic smoke test to guard future macro regressions. 3. `.claude/rules/plugins.md` `## Plugin trait extensions` section listed `path_aliases` and `virtual_module_prefixes` but not the new `virtual_package_suffixes`. Add it with a one-line description and a Vitest example.
Collaborator
|
Released in v2.63.0. Thanks @fmguerreiro. |
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Problem
Vitest's manual-mock convention places mock factories at
<package>/__mocks__/<module>.tsand triggers them viavi.mock('<module>'). Some test setups also import directly from@<scope>/__mocks__paths viapackage.json#importsaliases or workspace virtual paths:```ts
import { mockS3Send } from '@aws-sdk/mocks';
```
Fallow flags these as
unlisted-dep, and the auto-fix suggests "install@aws-sdk/__mocks__" — a package that doesn't exist on npm. Same for@sentry/__mocks__,@supabase/__mocks__,@mapbox/__mocks__, etc.Fix
Adds a sibling abstraction to the existing
virtual_module_prefixes(prefix-based matching used by Nuxt, Docusaurus, etc.):virtual_module_prefixes()virtual_package_suffixes()&[]&[]"#""/__mocks__"VitestPlugin::virtual_package_suffixesreturns&["/__mocks__"]. Thefind_unlisted_dependenciesfilter skips anypackage_nameending with a registered suffix.Workspace aggregation
Critical detail: the suffix list must be merged from per-workspace plugin runs into the root
AggregatedPluginResult. When Vitest is in a workspace'spackage.json(not the root) — common in monorepos — the suffix gets registered locally and would be dropped before the analyzer reads it.run_pluginsinlib.rsnow mergesvirtual_package_suffixesalongsidevirtual_module_prefixesandgenerated_import_patternsvia a smallextend_uniquehelper that consolidates the three identical dedup loops.Tests
VitestPlugin::virtual_package_suffixes: scoped/unscoped match plus 6-case adversarial negative (__mocks__-helper,my__mocks__pkg,@scope/__mocks__-utilsetc.).find_unlisted_dependencies:@aws-sdk/__mocks__andsome-pkg/__mocks__fully suppressed.tests/fixtures/vitest-mocks-virtual/: single-package, Vitest at root.tests/fixtures/vitest-mocks-workspace/: monorepo, Vitest only inapps/mrv/package.json. Reproduces the workspace-aggregation case the unit tests alone cannot catch.API surface
Plugin::virtual_package_suffixes(&self) -> &'static [&'static str]with default&[]. Backwards-compatible: existing plugins inherit the default. NewAggregatedPluginResult.virtual_package_suffixes: Vec<String>field flows through the existing aggregation path.Verified on
cargo test --workspace(1909 lib + 299 integration tests passing),cargo clippy --workspace --all-targets -- -D warnings,cargo fmt --all -- --check. Real-world: this fork-pinned binary running in a Turborepo monorepo CI cleared all 5@*/__mocks__false positives.