functionalscript · sergey-shandar · Aug 13, 2026 · Aug 13, 2026 · Aug 13, 2026 · Aug 13, 2026
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -401,7 +401,7 @@
           "run": "deno install --frozen"
         },
         {
-          "run": "deno test --allow-read --allow-env --allow-sys --coverage && deno coverage --include='.*module\\.f\\.(ts|mjs)'"
+          "run": "deno task cov"
         }
       ]
     },

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -20,6 +20,15 @@ history.
 
 ## Unreleased
 
+- **BREAKING CHANGES:** `fjs/ci/deno` no longer exports `coverageInclude`.
+  The Deno CI job runs `deno task cov`, so `deno.json` owns the coverage
+  filter, matching how the Node jobs leave `npm run cov` to `package.json`
+  [#1512](https://github.com/functionalscript/functionalscript/pull/1512)
+- `npm run cov` names its test entrypoint instead of relying on
+  `node --test` default discovery, which silently reported no tests on some
+  Node versions. The dead `.f.ts` extension is dropped from the Node and
+  Deno coverage filters
+  [#1512](https://github.com/functionalscript/functionalscript/pull/1512)
 - **BREAKING CHANGES:** `fjs/djs/examples/input.f.ts` and
   `fjs/djs/examples/m.f.ts` migrate to `.f.mjs`. Being `.mjs` they now
   ship in the tarball, which `.f.ts` did not

diff --git a/deno.json b/deno.json
@@ -2,7 +2,7 @@
   "tasks": {
     "fjs": "deno run --allow-read --allow-write --allow-env --allow-net --allow-sys ./fjs/module.mjs",
     "test": "deno test --allow-read --allow-env --allow-sys",
-    "cov": "deno test --allow-read --allow-env --allow-sys --coverage && deno coverage --include='.*module\\.f\\.(ts|mjs)'"
+    "cov": "deno test --allow-read --allow-env --allow-sys --coverage && deno coverage --include='.*module\\.f\\.mjs'"
   },
   "fmt": {
     "indentWidth": 4,

diff --git a/fjs/ci/deno/module.f.mjs b/fjs/ci/deno/module.f.mjs
@@ -2,6 +2,11 @@
  * CI step builder for Deno: installs the pinned Deno version and runs the
  * FunctionalScript package smoke test plus Deno coverage in one canonical job.
  *
+ * Coverage runs through `deno task cov`, so `deno.json` owns the permission set
+ * and the coverage filter, exactly as `npm run cov` leaves them to
+ * `package.json` for the Node jobs. The two `cov` definitions select the same
+ * modules and should stay semantically equal.
+ *
  * @module
  *
  * @import { MetaStep } from '../common/types.ts'
@@ -10,17 +15,6 @@
 import { deno } from '../config/module.f.mjs'
 import { install, test, uses } from '../common/module.f.mjs'
 
-const denoTest = 'deno test --allow-read --allow-env --allow-sys'
-
-/**
- * The regular expression selecting FunctionalScript implementation modules for
- * Deno coverage. Both authored extensions are included so a module migrated
- * from `.f.ts` to `.f.mjs` stays in the report. Keep it semantically equal to
- * the `--test-coverage-include` list in `package.json` and to the `cov` task in
- * `deno.json`.
- */
-export const coverageInclude = '.*module\\.f\\.(ts|mjs)'
-
 /** @type {(version: string) => readonly MetaStep[]} */
 export const denoSteps = version => [
     install(uses('denoland/setup-deno', { 'deno-version': deno })),
@@ -31,5 +25,5 @@ export const denoSteps = version => [
     install({ run: `deno install -g -A --minimum-dependency-age=0 npm:functionalscript@${version}` }),
     test({ run: `deno run -A --minimum-dependency-age=0 npm:functionalscript@${version} test` }),
     test({ run: 'deno install --frozen' }),
-    test({ run: `${denoTest} --coverage && deno coverage --include='${coverageInclude}'` }),
+    test({ run: 'deno task cov' }),
 ]
diff --git a/fjs/ci/deno/proof.f.mjs b/fjs/ci/deno/proof.f.mjs
@@ -1,25 +1,21 @@
-import { coverageInclude, denoSteps } from './module.f.mjs'
+import { denoSteps } from './module.f.mjs'
 import { toSteps } from '../common/module.f.mjs'
 import { assert, assertEq } from '../../asserts/module.f.mjs'
 
 /** @type {(version: string) => readonly string[]} */
 const coverageRuns = version =>
     toSteps(denoSteps(version))
-        .flatMap(s => s.run !== undefined && s.run.includes('deno coverage') ? [s.run] : [])
+        .flatMap(s => s.run !== undefined && s.run.includes('cov') ? [s.run] : [])
 
 export const proof = {
-    // A regression guard: dropping either authored implementation extension
-    // from the Deno coverage filter silently removes those modules from the
-    // CI coverage report while CI still passes.
-    coverageInclude: () => {
-        assertEq(coverageInclude, '.*module\\.f\\.(ts|mjs)')
-    },
+    // A regression guard: the job must delegate coverage to `deno.json`'s `cov`
+    // task. Inlining the command here instead would give the coverage filter a
+    // second owner that can silently drift from `deno.json`.
     coverageStep: () => {
         const runs = coverageRuns('0.0.0')
         assertEq(runs.length, 1)
         const [run] = runs
-        assert(run !== undefined)
-        assert(run.includes(`deno coverage --include='${coverageInclude}'`))
+        assertEq(run, 'deno task cov')
     },
     installsPinnedVersion: () => {
         const runs = toSteps(denoSteps('1.2.3'))

diff --git a/fjs/ci/proof.f.mjs b/fjs/ci/proof.f.mjs
@@ -4,7 +4,6 @@
 import { ci, main } from './module.f.mjs'
 import { functionalscript, node } from './config/module.f.mjs'
 import { nodeNixJobs } from './node/module.f.mjs'
-import { coverageInclude } from './deno/module.f.mjs'
 import { utf8, utf8ToString } from '../text/module.f.mjs'
 import { empty as emptyVec } from '../types/bit_vec/module.f.mjs'
 import { test, ubuntu, parseGitHubAction } from './common/module.f.mjs'
@@ -163,7 +162,7 @@ export const proof = {
             assert(hasRun(`deno install -g -A --minimum-dependency-age=0 npm:functionalscript@${functionalscript}`)(gha), 'expected configured-version deno install cache')
             assert(hasRun('deno install --frozen')(gha), 'expected deno lock install')
             assert(hasRun(`deno run -A --minimum-dependency-age=0 npm:functionalscript@${functionalscript} test`)(gha), 'expected configured-version deno install')
-            assert(hasRun(`deno test --allow-read --allow-env --allow-sys --coverage && deno coverage --include='${coverageInclude}'`)(gha), 'expected limited-permission deno coverage')
+            assert(hasRun('deno task cov')(gha), 'expected deno coverage task')
             assert(hasRun(`bun install -g functionalscript@${functionalscript}`)(gha), 'expected configured-version bun cache')
             assert(hasRun('bun install --frozen-lockfile')(gha), 'expected bun lock install')
             assert(hasRun(`bunx functionalscript@${functionalscript} test`)(gha), 'expected configured-version bun install')

diff --git a/fjs/emergent_testing/module.f.mjs b/fjs/emergent_testing/module.f.mjs
@@ -122,10 +122,12 @@ export const collectTests = (path, throws, v) => {
 export const registerModule = (ctx, k, v, star) => {
     /** @type {(ctx: TestContext, entry: _TestAndPath) => Effect<Test | All | Await, void>} */
     const registerOne = (ctx, [path, { fn, throws }]) => {
-        // ' *' (non-empty only for Bun) signals that all sub-tests run
-        // inline inside this single registration. Not appended to throw-tests since
-        // those never produce sub-tests. The path already contains '.throw' when a
-        // test is expected to throw, so no extra suffix is needed.
+        // `star` (non-empty for Bun and for Node below the 26 baseline) signals
+        // that all sub-tests run inline inside this single registration, so an
+        // external runner reports fewer tests than `fjs t` for the same suite.
+        // Not appended to throw-tests since those never produce sub-tests. The
+        // path already contains '.throw' when a test is expected to throw, so no
+        // extra suffix is needed.
         const base = fmtImport(k, path)
         const name = throws ? base : `${base}${star}`
         return test(ctx, name, throws, (/** @type {TestContext} */ t) =>

diff --git a/fjs/emergent_testing/todo/f-mjs-test-and-coverage.md b/fjs/emergent_testing/todo/f-mjs-test-and-coverage.md
@@ -9,7 +9,8 @@
 Tooling recognition of `.f.mjs` has landed: `shouldLoad` in
 `fjs/dev/module.f.mjs` matches `.f.mjs`, `npm run cov` and `deno task cov`
 include `module.f.mjs`, and the canonical Deno CI generator
-(`fjs/ci/deno/module.f.mjs`) exports `coverageInclude` with a regression proof.
+(`fjs/ci/deno/module.f.mjs`) delegates to `deno task cov` with a regression
+proof, so `deno.json` is the only owner of the Deno coverage filter.
 
 What is still missing is end-to-end evidence from an actual `.f.mjs` runtime
 fixture. No repository fixture currently proves that a migrated

diff --git a/package.json b/package.json
@@ -12,7 +12,7 @@
   "scripts": {
     "prepack": "tsc --noEmit false --emitDeclarationOnly && tsc --noEmit false --declaration false",
     "test": "tsc && node ./fjs/module.mjs t",
-    "cov": "node --test --experimental-test-coverage --test-coverage-include=**/module.f.ts --test-coverage-include=**/module.f.mjs",
+    "cov": "node --test --experimental-test-coverage --test-coverage-include=**/module.f.mjs fjs/emergent_testing/all.test.ts",
     "start": "node ./fjs/module.mjs",
     "ci-update": "node ./fjs/module.mjs ci && node ./fjs/module.mjs r ./fjs/nanvm/update/module.f.mjs",
     "dev-update": "node ./fjs/module.mjs r ./fjs/dev/update/module.f.mjs",

diff --git a/todo/migrate-typescript-to-mjs.md b/todo/migrate-typescript-to-mjs.md
@@ -820,38 +820,48 @@ Each item below is stated with the measurement that produced it, so the next
 person can re-check rather than re-derive. Counts are as of
 [#1505](https://github.com/functionalscript/functionalscript/pull/1505).
 
-- [ ] **Make `npm run cov` report real coverage.** It has been vacuous for
-      several PRs — reviewers keep reporting `100.00` over 0 tests and having to
-      exclude coverage from their verification — but *not* because of the
-      include globs, so do not start there. The script already passes
-      `--test-coverage-include=**/module.f.mjs` alongside the now-dead
-      `**/module.f.ts` (the `.mjs` glob was added in #1422). Dropping the dead
-      glob is worth doing but changes nothing measurable:
-      `--test-coverage-include` only filters which files appear in the report,
-      so it cannot make a run that executed nothing report something.
-
-      The cause is test *discovery*. With no path arguments `node --test` looks
-      for its own default patterns (`*.test.*`, `test.*`, `*-test.*`,
-      `test-*.*`, `*_test.*`, `test/**`); the repo's proofs are `proof.f.mjs` /
-      `module.f.mjs` and match none of them. The only file in the tree that does
-      match is `fjs/emergent_testing/all.test.ts`, and what happens then is
-      Node-version-dependent — on v23 the run reports 0 tests, while on v22.22.2
-      it discovers that file and executes the suite through it. The real suite
-      runs via the repo's own runner (`npm test` -> `node ./fjs/module.mjs t`,
-      2495 tests). `scenarios/run.sh` corroborates the discovery problem: it
-      hard-links `all.ts` to `_all.test.ts` precisely so `node --test` will find
-      it.
-
-      So restoring the signal means giving `node --test` entrypoints it actually
-      runs, or collecting coverage through `fjs`'s runner — not editing globs.
-      The cheapest candidate is naming the entrypoint in the script, which is
-      measured to work on both versions: adding
-      `fjs/emergent_testing/all.test.ts` as a path argument to `cov` yields
-      `tests 2431 / pass 2431 / fail 0` and a real per-file report on v22.22.2,
-      and the same file named explicitly also runs on v23. Confirm it reports on
-      whichever Node CI uses before adopting it, and pin that version — the
-      2431 here against 2495 from `npm test` is a second discrepancy worth
-      understanding rather than papering over.
+- [x] **Make `npm run cov` report real coverage.** Done: `cov` now names its
+      entrypoint (`fjs/emergent_testing/all.test.ts`) instead of relying on
+      `node --test` default discovery, and the dead `**/module.f.ts` glob is
+      gone.
+
+      The diagnosis above was right and the "vacuous for several PRs" framing
+      was wrong, so both are recorded here rather than deleted. The cause was
+      test *discovery*: with no path arguments `node --test` looks for its own
+      default patterns (`*.test.*`, `test.*`, `*-test.*`, `test-*.*`,
+      `*_test.*`, `test/**`); the repo's proofs are `proof.f.mjs` /
+      `module.f.mjs` and match none of them, and the only file in the tree that
+      does is `fjs/emergent_testing/all.test.ts`. Whether that file is picked up
+      is Node-version-dependent, because it is TypeScript. Measured with the
+      pre-fix command
+      (`node --test --experimental-test-coverage --test-coverage-include=**/module.f.ts --test-coverage-include=**/module.f.mjs`):
+
+      | Node | tests | coverage report |
+      |---|---|---|
+      | 22.22.2 | 2431 | yes, `all files 99.93` |
+      | 23.11.1 | **0** | **none** |
+      | 24.18.1 | 2431 | yes, `all files 99.93` |
+      | 26.7.0 | 2495 | yes, `all files 99.93` |
+
+      So every Node version CI actually runs (`22.23.2`, `24.18.1`, `26.7.0` in
+      the `node22` / `node24` / `node26` jobs) already reported real coverage;
+      v23 — released, EOL, not in CI — is the version that reports nothing. The
+      fix removes the dependency on default discovery altogether: naming the
+      entrypoint yields the same counts and the same `99.93` report on 22, 24
+      and 26, and turns v23's `tests 0` into `tests 2431` with a full report.
+
+      The 2431-vs-2495 gap is **not** a second defect. It is exactly the 64
+      sub-tests — those reachable only through a test function's *return value*.
+      `usesInlineTestContext` (`fjs/effects/node/module.f.mjs`) selects the
+      flattened registration strategy below the Node 26 baseline, where
+      `inlineContext` runs sub-tests inside their parent registration instead of
+      declaring them to the framework, so the framework counts the parent only.
+      Node 26 uses native `expectFailure` and nested registration, and counts
+      all 2495, matching `npm test` (`node ./fjs/module.mjs t`). Measured on
+      26.7.0: 2431 top-level plus 64 nested `✔` lines; on 24.18.1: 2431
+      top-level, 0 nested, of which 2376 carry the ` ...` inline marker (the
+      remaining 55 are throw-tests, which never produce sub-tests). Same work
+      executed either way — only the reported count differs.
 - [ ] **Settle whether generated `types.js` is required for portable
       resolution.** This gates the two items after it and is the one open
       correctness risk for published consumers. After `npm run prepack`,
-Original file line number
+Diff line change
@@ Expand Up / @@ -401,7 +401,7 @@ @@
               "run": "deno install --frozen"
             },
             {
-              "run": "deno test --allow-read --allow-env --allow-sys --coverage && deno coverage --include='.*module\\.f\\.(ts|mjs)'"
+              "run": "deno task cov"
             }
           ]
         },
@@ Expand Down @@