[lldb-dap][ext] Setup tests for lldb-dap extension (#174641)

This add the basic unit test support for the dap-extension. 
It also 
- adds a .prettierignore file to exclude folder not to format.
- Includes the test folder in when formatting.

uses `vscode-test` from
https://code.visualstudio.com/api/working-with-extensions/testing-extension#quick-setup-the-test-cli
Follow up from
https://github.com/llvm/llvm-project/pull/162635#discussion_r2486112688

lldb/tools/lldb-dap/extension/.prettierignore

@@ -0,0 +1,9 @@
+# ignore build artefacts
+node_folder/
+out/
+.vscode-test/
+
+# user settings
+.vscode
+
+package-lock.json

lldb/tools/lldb-dap/extension/.vscode-test.mjs

@@ -0,0 +1,8 @@
+import { defineConfig } from "@vscode/test-cli";
+
+export default defineConfig([
+  {
+    label: "unitTests",
+    files: "out/test/unit/**/*.test.js",
+  },
+]);

lldb/tools/lldb-dap/extension/package.json

@@ -33,11 +33,15 @@
   "devDependencies": {
     "@types/node": "^18.19.41",
     "@types/tabulator-tables": "^6.2.10",
+    "@types/mocha": "^10.0.10",
     "@types/vscode": "1.75.0",
     "@types/vscode-webview": "^1.57.5",
     "@vscode/debugprotocol": "^1.68.0",
+    "@vscode/test-cli": "^0.0.12",
+    "@vscode/test-electron": "^2.5.2",
     "@vscode/vsce": "^3.2.2",
     "esbuild": "^0.25.9",
+    "mocha": "^10.2.0",
     "prettier": "^3.4.2",
     "prettier-plugin-curly": "^0.3.1",
     "prettier-plugin-organize-imports": "^4.3.0",
@@ -56,9 +60,12 @@
     "bundle-webview": "npm run bundle-symbols-table-view && npm run bundle-tabulator",
     "vscode:prepublish": "npm run bundle-webview && npm run bundle-extension",
     "watch": "npm run bundle-webview && tsc -watch -p ./",
-    "format": "npx prettier './src/' --write",
+    "format": "npx prettier . --write",
     "package": "rm -rf ./out && vsce package --out ./out/lldb-dap.vsix",
+    "compile": "tsc -p ./",
     "publish": "vsce publish",
+    "pretest": "npm run compile",
+    "test": "vscode-test",
     "vscode-uninstall": "code --uninstall-extension llvm-vs-code-extensions.lldb-dap",
     "vscode-install": "code --install-extension ./out/lldb-dap.vsix"
   },

lldb/tools/lldb-dap/extension/src/utils.ts

@@ -5,7 +5,7 @@ import * as path from "path";
  * Expands the character `~` to the user's home directory
  */
 export function expandUser(file_path: string): string {
-  if (os.platform() == "win32") {
+  if (os.platform() === "win32") {
     return file_path;
   }
 
@@ -18,22 +18,22 @@ export function expandUser(file_path: string): string {
   }
 
   const path_len = file_path.length;
-  if (path_len == 1) {
+  if (path_len === 1) {
     return os.homedir();
   }
 
-  if (file_path.charAt(1) == path.sep) {
+  if (file_path.charAt(1) === path.sep) {
     return path.join(os.homedir(), file_path.substring(1));
   }
 
   const sep_index = file_path.indexOf(path.sep);
-  const user_name_end = sep_index == -1 ? file_path.length : sep_index;
+  const user_name_end = sep_index === -1 ? file_path.length : sep_index;
   const user_name = file_path.substring(1, user_name_end);
   try {
-    if (user_name == os.userInfo().username) {
+    if (user_name === os.userInfo().username) {
       return path.join(os.homedir(), file_path.substring(user_name_end));
     }
-  } catch (err) {
+  } catch (error) {
     return file_path;
   }
 

lldb/tools/lldb-dap/extension/test/unit/expandUser.test.ts

@@ -0,0 +1,44 @@
+import * as assert from "assert";
+import * as os from "os";
+import * as process from "process";
+import { expandUser } from "../../src/utils";
+
+suite("expandUser Test", function () {
+  const home_env: { [key: string]: string | undefined } = {};
+  const local_username = os.userInfo().username;
+
+  suiteSetup(function () {
+    if (os.platform() === "win32") {
+      this.skip();
+    }
+    home_env.HOME = process.env.HOME;
+    process.env.HOME = "/home/buildbot";
+  });
+
+  suiteTeardown(function () {
+    process.env.HOME = home_env.HOME;
+  });
+
+  test("tilde ", function () {
+    assert.equal(expandUser("~"), "/home/buildbot");
+    assert.equal(expandUser("~/"), "/home/buildbot/");
+    assert.equal(expandUser("~/worker"), "/home/buildbot/worker");
+  });
+
+  test("tilde with username", function () {
+    assert.equal(expandUser(`~${local_username}`), "/home/buildbot");
+    assert.equal(expandUser(`~${local_username}/`), "/home/buildbot/");
+    assert.equal(expandUser(`~${local_username}/dev`), "/home/buildbot/dev");
+
+    // test unknown user
+    assert.notEqual(expandUser("~not_a_user"), "/home/build/bot");
+  });
+
+  test("empty", function () {
+    assert.equal(expandUser(""), "");
+  });
+
+  test("no tilde", function () {
+    assert.equal(expandUser("/home/buildbot/worker"), "/home/buildbot/worker");
+  });
+});

lldb/tools/lldb-dap/extension/tsconfig.json

@@ -3,16 +3,11 @@
 		"moduleResolution": "node",
 		"module": "commonjs",
 		"outDir": "out",
-		"rootDir": "src",
+		"rootDir": ".",
 		"sourceMap": true,
 		"strict": true,
 		"target": "es6"
 	},
-	"include": [
-		"src"
-	],
-	"exclude": [
-		"node_modules",
-		"src/webview",
-	]
+	"include": ["src", "test"],
+  	"exclude": [".vscode-test", "node_modules", "src/webview"]
 }