test: say which CI job and which files the discovery guard covers

scripts/run-unit-tests.mjs

@@ -25,10 +25,11 @@ export function assertNode24AllocationRuntime(version = process.versions.node) {
  * Directories this runner searches for `*.test.mjs`, in stable order.
  *
  * `server/` belongs here because provider modules own tests of their own: a
- * suite placed beside the module it covers must run, and `npm test` is the only
- * thing CI invokes, so a directory missing from this list is a suite that never
- * runs anywhere. `unitTestRunner.test.mjs` asserts the list covers every test
- * file in the repository, so adding a tree without adding it here fails.
+ * suite placed beside the module it covers must run, and CI's unit-test job runs
+ * `npm test`, so a directory missing from this list is a suite that never runs
+ * there. `unitTestRunner.test.mjs` asserts the list covers every `*.test.mjs`
+ * outside dependencies, build output and dot-directories, so adding a tree
+ * without adding it here fails.
  */
 export const UNIT_TEST_ROOTS = Object.freeze(['src', 'server']);
 

src/unitTestRunner.test.mjs

@@ -64,11 +64,12 @@ test('unit runner serializes only GC-bracketed allocation microbenchmarks', () =
 });
 
 test('the runner discovers every test file in the repository', () => {
-  // `npm test` is the only suite CI runs, and it runs exactly what this
-  // function returns. A `*.test.mjs` outside the searched roots therefore never
-  // executes anywhere, while still reading — in review and to its author — like
-  // covered code. Compare the two sets rather than their sizes, so the failure
-  // names the files instead of only disagreeing about a count.
+  // CI's unit-test job runs `npm test`, which runs exactly what this function
+  // returns. A `*.test.mjs` outside the searched roots therefore never runs
+  // there, while still reading — in review and to its author — like covered
+  // code. Compare the two sets rather than their sizes, so the failure names the
+  // files instead of only disagreeing about a count. The final equality also
+  // catches the reverse: files the runner finds that this walk skips.
   const discovered = discoverUnitTestFiles(repositoryRoot);
   const onDisk = testFilesOnDisk(repositoryRoot);
   const undiscovered = onDisk.filter((file) => !discovered.includes(file));