test(vue): add tests (#22089)

packages/vue-router/test/jest.preprocessor.js

@@ -0,0 +1,14 @@
+const tsc = require('typescript');
+const tsConfig = require('../tsconfig.json');
+
+// force the output to use commonjs modules required by jest
+tsConfig.compilerOptions.module = 'commonjs';
+
+module.exports = {
+  process(src, path) {
+    if (path.endsWith('.ts') || path.endsWith('.tsx')) {
+      return tsc.transpile(src, tsConfig.compilerOptions, path, []);
+    }
+    return src;
+  },
+};