typescript: Register ts-node to run TS modules in frontend tests.

frontend_tests/zjsunit/index.js

@@ -1,3 +1,13 @@
+require('ts-node').register({
+    project: 'static/ts/tsconfig.json',
+    compilerOptions: {
+        typeRoots: ["node_modules/@types", "../../static/ts/js_typings"],
+        // We don't have webpack to handle es6 modules here so directly
+        // transpile to CommonJS format.
+        module: "commonjs",
+    },
+});
+
 var path = require('path');
 var fs = require('fs');
 

frontend_tests/zjsunit/namespace.js

@@ -20,12 +20,19 @@ exports.patch_builtin = function (name, val) {
 };
 
 exports.zrequire = function (name, fn) {
+    var path;
     if (fn === undefined) {
-        fn = 'js/' + name;
+        try {
+            path = require.resolve('js/' + name);
+        } catch (_e /* MODULE_NOT_FOUND */) {
+            path = require.resolve('ts/' + name);
+        }
+    } else {
+        path = require.resolve(fn);
     }
-    delete require.cache[require.resolve(fn)];
-    var obj = require(fn);
-    requires.push(fn);
+    delete require.cache[path];
+    var obj = require(path);
+    requires.push(path);
     set_global(name, obj);
     return obj;
 };