Jest to Vitest migration (#230)

* working without clean up

* clean up dependencies

* use test not dev

* add tests for kclErrToDiagnostic

* remove jest config

* remove unneeded @ts-ignore

vite.config.ts

@@ -2,7 +2,7 @@ import react from '@vitejs/plugin-react'
 import viteTsconfigPaths from 'vite-tsconfig-paths'
 import eslint from 'vite-plugin-eslint'
 import dns from 'dns'
-import { defineConfig } from 'vite'
+import { defineConfig } from 'vitest/config';
 
 // Only needed because we run Node < 17 
 // and we want to open `localhost` not `127.0.0.1` on server start
@@ -14,6 +14,14 @@ const config = defineConfig({
     open: true,
     port: 3000,
   },
+  test: {
+    globals: true,
+    setupFiles: 'src/setupTests.ts',
+    environment: 'happy-dom',
+    coverage: {
+      provider: 'istanbul' // or 'v8'
+    },
+  },
   build: {
     outDir: 'build',
   },