add vitest test data plugin

doc/VITEST.md

@@ -0,0 +1,35 @@
+# Vitest Test Data
+
+This package also supports collecting the test data of projects that are using Vitest (0.x).
+
+## Usage
+
+### Basic usage
+
+#### Vitest
+
+If you use **Vitest**, you can add the following to your `vitest.config.js` file:
+
+```javascript
+import { VitestTestDataPlugin } from '@agoda-com/test-metrics'
+
+export default defineConfig({
+  ...,
+  test: {
+    ...,
+    reporters: ['default', new VitestTestDataPlugin()],
+  },
+})
+```
+
+Don't forget to keep `'default'` reporter in the list, otherwise you won't be able to see your test result in the console.
+
+### Advanced usage
+
+As same as build time, test data collection also sends the command that you used to run the build like `yarn test` to be the custom identifier which should work in most cases in order to help you distinguish between different test configurations.
+
+However, if you would like to define your own identifier, you can do so by passing it as a parameter to the plugin.
+
+```javascript
+VitestTestDataPlugin(testOnlyPartA ? 'test-only-part-a' : 'test-everything');
+```