ci: unit test coverage in the job summary, held to a floor

.github/workflows/ci.yml

@@ -42,6 +42,16 @@ jobs:
         with:
           go-version-file: go.mod
       - run: go tool task ci
+      # The coverage task test wrote, even when a test failed: the summary says so when there is none.
+      - if: always()
+        run: go tool task coverage:summary
+      - if: always()
+        uses: actions/upload-artifact@cf430e030ddbb5b0abf93d22962f4752f3646cd9 # v7.0.2
+        with:
+          name: coverage-web
+          path: coverage
+          retention-days: 7
+          if-no-files-found: ignore
 
   integration:
     name: Integration

.gitignore

@@ -7,3 +7,4 @@ dist-test/
 build/
 bin/
 .wt/
+coverage/

Taskfile.yml

@@ -33,11 +33,16 @@ tasks:
       - pnpm typecheck
 
   test:
-    desc: The unit tests - Vitest, against the fake spin in test/fake-spin/, and hack/'s Go.
+    desc: The unit tests - Vitest, against the fake spin in test/fake-spin/, with coverage held to the floor in vitest.config.mts - and hack/'s Go.
     cmds:
       - pnpm test
       - go test ./hack/...
 
+  coverage:summary:
+    desc: The coverage task test left in coverage/, as the job's summary (hack/coverage-summary.mjs); the HTML is coverage/index.html.
+    cmds:
+      - node hack/coverage-summary.mjs
+
   test:cli:
     desc: The extension's reader against the real spin CLI of the pinned release (test/cli/), pulled and checked by package:spin - minutes, so it is not in task test.
     cmds:

hack/coverage-summary.mjs

@@ -0,0 +1,29 @@
+// The unit tests' coverage, from what `vitest run --coverage` writes into coverage/, as the job's
+// summary (stdout outside a workflow). The HTML beside it is the coverage-web artifact.
+import { appendFileSync, existsSync, readFileSync } from "node:fs"
+
+const file = "coverage/coverage-summary.json"
+const write = (text) => {
+  const summary = process.env.GITHUB_STEP_SUMMARY
+  if (summary) appendFileSync(summary, `${text}\n`)
+  else console.log(text)
+}
+
+if (!existsSync(file)) {
+  write(`${file} was not produced; the tests may have failed before coverage ran.`)
+} else {
+  const { total } = JSON.parse(readFileSync(file, "utf8"))
+  const rows = ["statements", "branches", "functions", "lines"].map((key) => {
+    const { covered, total: all, pct } = total[key]
+    return `| ${key} | ${covered} | ${all} | ${pct}% |`
+  })
+  write(
+    [
+      "## Unit test coverage",
+      "",
+      "| Metric | Covered | Total | % |",
+      "|---|---:|---:|---:|",
+      ...rows,
+    ].join("\n"),
+  )
+}

package.json

@@ -210,7 +210,7 @@
     "lint": "biome check .",
     "lint:fix": "biome check --write .",
     "typecheck": "tsc --noEmit",
-    "test": "vitest run",
+    "test": "vitest run --coverage",
     "test:cli": "vitest run --config vitest.cli.config.mts",
     "test:integration": "node esbuild.mjs --tests && node test/integration/run.mjs",
     "package": "vsce package --no-dependencies --out spinbox.vsix"
@@ -219,6 +219,7 @@
     "@biomejs/biome": "2.6.3",
     "@types/node": "22.20.5",
     "@types/vscode": "1.146.0",
+    "@vitest/coverage-v8": "5.0.5",
     "@vscode/test-electron": "3.1.0",
     "@vscode/vsce": "4.1.0",
     "esbuild": "0.28.2",

vitest.config.mts

@@ -3,5 +3,17 @@ import { defineConfig } from "vitest/config"
 export default defineConfig({
   test: {
     include: ["test/unit/**/*.test.ts"],
+    coverage: {
+      provider: "v8",
+      // Every file under src/, so one no unit test imports counts as uncovered rather than absent.
+      include: ["src/**"],
+      // json-summary is what CI's job summary reads (hack/coverage-summary.mjs); reportOnFailure
+      // keeps a red suite from leaving it nothing to read.
+      reporter: ["text", "json-summary", "html"],
+      reportOnFailure: true,
+      // A floor below the 87.1% of statements measured on 2026-11-14. Raise it when the number has
+      // moved up and stayed; never lower it to let a change through.
+      thresholds: { statements: 85 },
+    },
   },
 })