Migrate test framework to vitest (microsoft#2769)

Get rid of mocha and upgrade to vitest which is a more modern
alternative providing, watch, direct typescript compilation out of the
box, expect library and more.

Advantage over mocha:
- Much better cli
  -  watch mode
  - better diff
- Better extension:
  -  tree organization for files too (not everything flattened)
- update in real time the test(no more need to refresh manually to
discover where are the tests)
  - just a little buggy
- Compiles typescript directly
- provides more expectation apis(like jest)

Cons over mocha: 
- Slower(about 2x) but that means we don't need to build the test as
part of build which would speed up that part(not as much as is lost)

Todo: 
- typespec-azure migration

Author: timotheeguerin

.vscode/extensions.json

@@ -2,6 +2,7 @@
   "recommendations": [
     "dbaeumer.vscode-eslint",
     "esbenp.prettier-vscode",
-    "streetsidesoftware.code-spell-checker"
+    "streetsidesoftware.code-spell-checker",
+    "ZixuanChen.vitest-explorer"
   ]
 }

.vscode/launch.json

@@ -20,26 +20,6 @@
         "order": 999
       }
     },
-    {
-      "type": "node",
-      "request": "attach",
-      "name": "Tests",
-      "port": 9229,
-      "smartStep": true,
-      "sourceMaps": true,
-      "continueOnAttach": true,
-      "skipFiles": [
-        "<node_internals>/**/*.js",
-        "**/.vscode/extensions/hbenl.vscode-mocha-test-adapter-*/**.js"
-      ],
-      "outFiles": [
-        "${workspaceFolder}/packages/*/dist/**/*.js",
-        "${workspaceFolder}/packages/*/dist-dev/**/*.js"
-      ],
-      "presentation": {
-        "hidden": true
-      }
-    },
     {
       "name": "Attach to Language Server",
       "type": "node",

.vscode/settings.json

@@ -54,23 +54,8 @@
   },
   "typescript.tsdk": "./packages/compiler/node_modules/typescript/lib",
   "git.ignoreLimitWarning": true,
-  "testExplorer.useNativeTesting": true,
-  "mochaExplorer.parallel": false,
-  "mochaExplorer.files": [
-    "./packages/*/dist/test/**/*.test.js",
-    "./packages/*/dist/test/**/*.e2e.js",
-    "./packages/*/dist-dev/test/**/*.test.js",
-    "./packages/*/test/**/*.test.js"
-  ],
-  "mochaExplorer.ignore": "./packages/*/dist/test/manual/**/*.js",
-  "mochaExplorer.mochaPath": "./packages/compiler/node_modules/mocha",
-  "mochaExplorer.timeout": 500000,
-  "mochaExplorer.require": "source-map-support/register",
-  "mochaExplorer.debuggerConfig": "Tests",
-  "mochaExplorer.env": {
-    "TYPESPEC_VERBOSE_TEST_OUTPUT": "true",
-    "NODE_OPTIONS": "--stack-trace-limit=50"
-  },
+  "vitest.enable": true,
+  "vitest.commandLine": "node ./packages/compiler/node_modules/vitest/vitest.mjs",
   "prettier.prettierPath": "./packages/compiler/node_modules/prettier/index.cjs",
   "prettier.documentSelectors": ["**/*.tsp"],
   "testExplorer.errorDecoration": false,

CONTRIBUTING.md

@@ -154,8 +154,8 @@ PR validation will ensure that reference docs are up to date.
 
 ## Recommended extensions
 
-1. [Mocha Test Explorer](https://marketplace.visualstudio.com/items?itemName=hbenl.vscode-mocha-test-adapter):
-   Run tests from the IDE.
+1. [Vitest Test Explorer](https://marketplace.visualstudio.com/items?itemName=ZixuanChen.vitest-explorer):
+   Run tests from the IDE. (Version `0.2.43` is bugged on OSX, use `0.2.42` instead)
 2. [Prettier](https://marketplace.visualstudio.com/items?itemName=esbenp.prettier-vscode):
    Automatically keep code formatted correctly on save.
 3. [ESLint](https://marketplace.visualstudio.com/items?itemName=dbaeumer.vscode-eslint):
@@ -191,17 +191,13 @@ Terminal pane will have three parallel watch tasks running:
 
 ## Testing
 
-With [Mocha Test
-Explorer](https://marketplace.visualstudio.com/items?itemName=hbenl.vscode-mocha-test-adapter)
-installed, click on its icon in the sidebar, then click on the play
-button at the top or on any individual test or test group to run just
-one test or just one group. You can also click on the bug icon next to
-an individual test to debug it.
-
-You can see additional information logged by each test using
-`logVerboseTestOutput` by clicking on the test and looking at the
-output pane. Unlike the command line, no environment variable is
-needed.
+```bash
+# Run all the tests
+rush test
+
+# Run in a specific package tests in watch mode
+npm run test:watch
+```
 
 ## Debugging
 

common/changes/@typespec/bundler/vitest_2023-12-22-02-02.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@typespec/bundler",
+      "comment": "",
+      "type": "none"
+    }
+  ],
+  "packageName": "@typespec/bundler"
+}

common/changes/@typespec/compiler/vitest_2023-12-22-02-02.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@typespec/compiler",
+      "comment": "",
+      "type": "none"
+    }
+  ],
+  "packageName": "@typespec/compiler"
+}

common/changes/@typespec/eslint-config-typespec/vitest_2023-12-27-18-29.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@typespec/eslint-config-typespec",
+      "comment": "Migrate test rules to vitest",
+      "type": "none"
+    }
+  ],
+  "packageName": "@typespec/eslint-config-typespec"
+}

common/changes/@typespec/eslint-plugin/vitest_2023-12-22-02-02.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@typespec/eslint-plugin",
+      "comment": "",
+      "type": "none"
+    }
+  ],
+  "packageName": "@typespec/eslint-plugin"
+}

common/changes/@typespec/html-program-viewer/vitest_2023-12-22-02-02.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@typespec/html-program-viewer",
+      "comment": "",
+      "type": "none"
+    }
+  ],
+  "packageName": "@typespec/html-program-viewer"
+}

common/changes/@typespec/http/vitest_2023-12-22-02-02.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@typespec/http",
+      "comment": "",
+      "type": "none"
+    }
+  ],
+  "packageName": "@typespec/http"
+}