add: testing exercise

Author: tnelson

F25/sep25_mocking_brain_jar/jest.config.js

@@ -0,0 +1,11 @@
+const { createDefaultPreset } = require("ts-jest");
+
+const tsJestTransformCfg = createDefaultPreset().transform;
+
+/** @type {import("jest").Config} **/
+module.exports = {
+  testEnvironment: "node",
+  transform: {
+    ...tsJestTransformCfg,
+  },
+};