Add extension contract tests

.github/workflows/extension-contract-tests.yaml

@@ -0,0 +1,20 @@
+name: Extension-Contract-Tests
+on: [workflow_call]
+permissions:
+  contents: read
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: test/extension-contract-tests
+    steps:
+      - uses: actions/checkout@v6
+      - uses: actions/setup-node@v6
+        with:
+          node-version: "22"
+          cache: "npm"
+          cache-dependency-path: "test/extension-contract-tests/package-lock.json"
+      - run: npm ci
+      - run: npm test
+      - run: npm run check:conformance

.github/workflows/main.yaml

@@ -13,6 +13,8 @@ jobs:
     uses: ./.github/workflows/agent.yaml
   vscode:
     uses: ./.github/workflows/vscode.yaml
+  extension-contract-tests:
+    uses: ./.github/workflows/extension-contract-tests.yaml
 
   connect-contract-tests:
     uses: ./.github/workflows/connect-contract-tests.yaml
@@ -62,6 +64,7 @@ jobs:
       [
         agent,
         vscode,
+        extension-contract-tests,
         connect-contract-tests,
         build,
         package,
@@ -92,6 +95,7 @@ jobs:
       [
         agent,
         vscode,
+        extension-contract-tests,
         connect-contract-tests,
         build,
         package,

.github/workflows/nightly.yaml

@@ -26,13 +26,24 @@ jobs:
   # Extensions
   vscode:
     uses: ./.github/workflows/vscode.yaml
+  extension-contract-tests:
+    uses: ./.github/workflows/extension-contract-tests.yaml
 
   connect-contract-tests:
     uses: ./.github/workflows/connect-contract-tests.yaml
 
   # Slack notification on failure
   slack-notification:
-    needs: [agent, build, package, e2e, vscode, connect-contract-tests]
+    needs:
+      [
+        agent,
+        build,
+        package,
+        e2e,
+        vscode,
+        extension-contract-tests,
+        connect-contract-tests,
+      ]
     if: failure()
     runs-on: ubuntu-latest
     steps:
@@ -51,7 +62,16 @@ jobs:
 
   # Slack notification when nightly tests recover from failure
   slack-notification-resolved:
-    needs: [agent, build, package, e2e, vscode, connect-contract-tests]
+    needs:
+      [
+        agent,
+        build,
+        package,
+        e2e,
+        vscode,
+        extension-contract-tests,
+        connect-contract-tests,
+      ]
     if: success()
     runs-on: ubuntu-latest
     steps:

.github/workflows/pull-request.yaml

@@ -89,6 +89,11 @@ jobs:
     if: needs.detect-changes.outputs.has-code == 'true'
     uses: ./.github/workflows/vscode.yaml
 
+  extension-contract-tests:
+    needs: detect-changes
+    if: needs.detect-changes.outputs.has-code == 'true'
+    uses: ./.github/workflows/extension-contract-tests.yaml
+
   connect-contract-tests:
     needs: detect-changes
     if: needs.detect-changes.outputs.has-code == 'true'

justfile

@@ -233,6 +233,22 @@ test *args=("-short ./..."):
 
     go test {{ args }} -covermode set -coverprofile=cover.out
 
+# Run extension contract tests (validates vscode/positron API usage)
+test-extension-contracts:
+    #!/usr/bin/env bash
+    set -eou pipefail
+    {{ _with_debug }}
+
+    cd test/extension-contract-tests && npm test
+
+# Check that vscode/positron mocks conform to real API type definitions
+check-extension-contract-conformance:
+    #!/usr/bin/env bash
+    set -eou pipefail
+    {{ _with_debug }}
+
+    cd test/extension-contract-tests && npm run check:conformance
+
 # Build the Connect API contract test harness binary
 build-connect-harness:
     go build -o test/connect-api-contracts/harness/harness ./test/connect-api-contracts/harness/

test/extension-contract-tests/README.md

@@ -0,0 +1,84 @@
+# Extension Contract Tests
+
+Contract tests that validate which **VSCode and Positron APIs** the extension calls, with what arguments, and what it expects back. These tests mock the `vscode` and `positron` modules, import actual extension code against those mocks, and assert API interactions.
+
+## Architecture
+
+```
+Test code  →  Import real extension module  →  Mock vscode/positron APIs
+               (e.g., src/dialogs.ts)           (vi.fn() spies record calls)
+```
+
+No Go binary, no HTTP server, no network. Tests run entirely in-process using Vitest with module aliasing to intercept `vscode` and `positron` imports.
+
+## What's tested
+
+Each test file captures the contract between extension code and the VSCode/Positron API surface:
+
+| Test File               | Extension Source            | APIs Validated                                                                       |
+| ----------------------- | --------------------------- | ------------------------------------------------------------------------------------ |
+| `positron-settings`     | `utils/positronSettings.ts` | `workspace.getConfiguration("positron.r")`                                           |
+| `extension-settings`    | `extension.ts`              | `workspace.getConfiguration("positPublisher")`                                       |
+| `dialogs`               | `dialogs.ts`                | `window.showInformationMessage` (modal), `l10n.t`                                    |
+| `window-utils`          | `utils/window.ts`           | `window.showErrorMessage`, `withProgress`, `createTerminal`                          |
+| `interpreter-discovery` | `utils/vscode.ts`           | `commands.executeCommand`, `workspace.getConfiguration`, Positron runtime            |
+| `file-watchers`         | `watchers.ts`               | `workspace.createFileSystemWatcher`, `RelativePattern`                               |
+| `llm-tools`             | `llm/index.ts`              | `lm.registerTool`                                                                    |
+| `open-connect`          | `open_connect.ts`           | `window.showInputBox`, `workspace.updateWorkspaceFolders`, `commands.executeCommand` |
+| `auth-provider`         | `authProvider.ts`           | `authentication.registerAuthenticationProvider`                                      |
+| `connect-filesystem`    | `connect_content_fs.ts`     | `workspace.registerFileSystemProvider`, `FileSystemError`                            |
+| `document-tracker`      | `entrypointTracker.ts`      | Editor/document change events, `commands.executeCommand("setContext")`               |
+| `activation`            | `extension.ts`              | `activate()` wiring: trust, URI handler, commands, contexts                          |
+
+## Mock design
+
+### `src/mocks/vscode.ts`
+
+Comprehensive mock of the `vscode` module with `vi.fn()` spies for all APIs the extension uses. Includes constructors (`Disposable`, `EventEmitter`, `Uri`, `RelativePattern`, etc.), enums (`FileType`, `ProgressLocation`, etc.), and namespace objects (`commands`, `window`, `workspace`, `authentication`, `lm`, `l10n`).
+
+### `src/mocks/positron.ts`
+
+Mock of the `positron` module providing `acquirePositronApi()` and the `LanguageRuntimeMetadata` type.
+
+### Conformance checks
+
+`src/mocks/vscode.conformance.ts` and `src/mocks/positron.conformance.ts` are compile-time checks that verify every property in our mocks also exists in the real API types. If a mock includes a misspelled or removed API, `tsc` will produce a compile error. Run with `npm run check:conformance`.
+
+### `src/helpers/`
+
+Shared mock setup used by tests that import modules with many transitive dependencies (e.g., `extension.ts`). Imported via `import "../helpers/extension-mocks"`.
+
+## Running
+
+```bash
+# Install dependencies (first time)
+cd test/extension-contract-tests && npm install
+
+# Run tests
+just test-extension-contracts
+
+# Or directly
+cd test/extension-contract-tests && npm test
+
+# Watch mode
+cd test/extension-contract-tests && npm run test:watch
+
+# Run conformance checks (verify mocks match real API types)
+just check-extension-contract-conformance
+
+# Or directly
+cd test/extension-contract-tests && npm run check:conformance
+```
+
+## Adding a new contract test
+
+1. Create a new file in `src/contracts/` following the naming convention: `<feature>.test.ts`
+2. Import `vi` from `vitest` and the relevant `vscode` APIs from the mock
+3. Mock any internal dependencies with `vi.mock("src/...")`
+4. Import the extension module under test with `await import("src/...")`
+5. Write tests that call extension functions and assert which VSCode APIs were invoked
+
+## Related test suites
+
+- Extension unit tests (`extensions/vscode/src/**/*.test.ts`) — Test internal logic
+- E2E tests (`test/e2e/`) — Full integration with Docker