feat: add e2e testing with @vscode/test-cli and wire it into CI

.github/workflows/ci.yml

@@ -60,3 +60,23 @@ jobs:
 
       - name: Build
         run: npm run build
+
+  e2e:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
+
+      - name: Setup Node.js
+        uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7
+        with:
+          node-version: 24.19.0
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Install Xvfb
+        run: sudo apt-get update && sudo apt-get install -y xvfb
+
+      - name: Run e2e tests
+        run: xvfb-run -a npm run test:e2e

.gitignore

@@ -1,6 +1,8 @@
 node_modules/
 dist/
 coverage/
+out-e2e/
+.vscode-test/
 .DS_Store
 *.log
 *.vsix

.vscode-test.mjs

@@ -0,0 +1,10 @@
+import { defineConfig } from '@vscode/test-cli';
+
+export default defineConfig({
+    files: 'out-e2e/**/*.test.js',
+    workspaceFolder: 'test/e2e/fixtures/workspace',
+    mocha: {
+        ui: 'bdd',
+        timeout: 20000
+    }
+});

.vscodeignore

@@ -3,10 +3,13 @@
 node_modules/**
 scripts/**
 test/**
+out-e2e/**
+.vscode-test/**
 extension.ts
 extension.ts.map
 tsconfig.json
 vitest.config.mts
+.vscode-test.mjs
 codecov.yml
 CLAUDE.md
 .gitignore

CLAUDE.md

@@ -20,8 +20,9 @@ drives versioning and publishing off Conventional Commit prefixes on `main`.
 
 Every change is expected to clear this bar before it's mergeable:
 
-- **CI clean.** `npm run lint` (`tsc --noEmit`), `npm run test`, and
-  `npm run build` all pass — see `.github/workflows/ci.yml`.
+- **CI clean.** `npm run lint` (`tsc --noEmit`), `npm run test`,
+  `npm run build`, and `npm run test:e2e` all pass — see
+  `.github/workflows/ci.yml`.
 - **Unit coverage ≥85%, both patch and project.** Codecov enforces this on
   every PR (`codecov.yml`: `project` and `patch`, both `target: 85%,
   threshold: 1%`), reported from `npm run test:coverage` (vitest + v8,
@@ -33,6 +34,16 @@ Every change is expected to clear this bar before it's mergeable:
   Codecov's patch gate computes, so a real gap shows up before a CI
   round-trip instead of after. Write real tests that close gaps for real —
   no padding, no vacuous assertions just to move a number.
+- **New features carry e2e coverage, not just unit tests.** Unit tests
+  (vitest, against `test/vscode-mock.ts`) cover logic in isolation;
+  `test/e2e/*.test.ts` (mocha, via `@vscode/test-cli` + `@vscode/test-electron`)
+  runs the real, built extension inside an actual VS Code Extension
+  Development Host — real command registration, real tree view, real
+  `workspaceState`. Any new user-facing command or tree behavior needs both:
+  a unit test for the logic and an e2e test exercising it end-to-end through
+  the real `vscode` API. Run locally with `npm run test:e2e` (builds the
+  extension, bundles `test/e2e/**` with esbuild, then launches the test
+  host — needs a display or `xvfb-run` on headless Linux).
 - **Security scanning clean.** CodeQL runs on every push/PR
   (`.github/workflows/codeql.yml`); `npm audit --audit-level=high` (via
   `scripts/wfb_dep_update.sh`) gates dependency updates on high/critical

extension.ts

@@ -65,7 +65,13 @@ export function computeReorderedIds<T extends { id: string; order?: number }>(
 const bookmarkFallbackCompare = (a: Bookmark, b: Bookmark) => b.createdAt - a.createdAt;
 const folderFallbackCompare = (a: BookmarkFolder, b: BookmarkFolder) => a.name.localeCompare(b.name);
 
-export function activate(context: vscode.ExtensionContext) {
+/** The extension's public API, returned from `activate()` — used by e2e tests to inspect state that isn't reachable through the tree view UI alone. */
+export interface ExtensionApi {
+    store: BookmarkStore;
+    provider: BookmarksTreeProvider;
+}
+
+export function activate(context: vscode.ExtensionContext): ExtensionApi {
     const store = new BookmarkStore(context);
     const provider = new BookmarksTreeProvider(store, context);
 
@@ -93,6 +99,8 @@ export function activate(context: vscode.ExtensionContext) {
         vscode.commands.registerCommand('workspace-file-bookmarks.setViewModeList', () => provider.setViewMode('list')),
         vscode.commands.registerCommand('workspace-file-bookmarks.setViewModeTree', () => provider.setViewMode('tree'))
     );
+
+    return { store, provider };
 }
 
 export function deactivate() {}