Verify react-native packager state is changed correctly when start and stop metro (#2413)

Author: EzioLi01

test/smoke/.mocharc.js

@@ -7,5 +7,7 @@ module.exports = {
     file: ["out/main.js"],
     extension: ["js"],
     slow: 200000,
-    timeout: 120000
+    timeout: 120000,
+    spec: "./out/**/*.test.js",
+    recursive: true,
 };

test/smoke/README.md

@@ -0,0 +1,11 @@
+# React Native Tools Functionality Smoke Tests
+Test cases of extension common E2E scenarios verification, include extension UI, commands, functionalities and other scenarios related to user experiences.<br>Tests are executed in vscode latest version without Extension Host.
+
+## Setup Tests
+In project root folder:<br>
+`npm run prepare-smoke-tests`: setup smoke test dependencies.<br>
+`npm run prepare-smoke-tests-project`: setup test sample project dependencies
+
+## Run Tests
+In project root folder:<br>
+`npm run smoke-tests`: Execute tests