Throw error when setting non-serializable macro config

packages/macros/src/macros-config.ts

@@ -193,6 +193,12 @@ export default class MacrosConfig {
       );
     }
 
+    if (!isSerializable(config)) {
+      throw new Error(
+        `[Embroider:MacrosConfig] the given config from '${fromPath}' for packageName '${packageName}' is not JSON serializable.`
+      );
+    }
+
     let targetPackage = this.resolvePackage(fromPath, packageName);
     let peers = getOrCreate(this.configs, targetPackage.root, () => []);
     peers.push(config);
@@ -421,3 +427,40 @@ function defaultMergerFor(pkgRoot: string) {
     return Object.assign({}, ...ownConfigs, ...otherConfigs);
   };
 }
+
+function isSerializable(obj: object): boolean {
+  if (isScalar(obj)) {
+    return true;
+  }
+
+  if (Array.isArray(obj)) {
+    return !obj.some((arrayItem: any) => !isSerializable(arrayItem));
+  }
+
+  if (isPlainObject(obj)) {
+    for (let property in obj) {
+      let value = obj[property] as any;
+      if (!isSerializable(value)) {
+        return false;
+      }
+    }
+
+    return true;
+  }
+
+  return false;
+}
+
+function isScalar(val: any): boolean {
+  return (
+    typeof val === 'undefined' ||
+    typeof val === 'string' ||
+    typeof val === 'boolean' ||
+    typeof val === 'number' ||
+    val === null
+  );
+}
+
+function isPlainObject(obj: any): obj is Record<string, any> {
+  return typeof obj === 'object' && obj.constructor === Object && obj.toString() === '[object Object]';
+}

packages/macros/tests/babel/set-config.test.ts

@@ -0,0 +1,42 @@
+import { MacrosConfig } from '../../src/node';
+import { allBabelVersions } from './helpers';
+
+describe(`setConfig`, function () {
+  allBabelVersions(function () {
+    test('works with empty config', () => {
+      let config = {};
+
+      let macroConfig = MacrosConfig.for({}, __dirname);
+      macroConfig.setConfig(__filename, 'qunit', config);
+    });
+
+    test('works with POJO config', () => {
+      let config = {
+        str: 'yes',
+        num: 10,
+        bool: true,
+        undef: undefined,
+        nil: null,
+        arr: ['yes', 10, true, undefined, null, { inArr: true }],
+        obj: { nested: true },
+      };
+
+      let macroConfig = MacrosConfig.for({}, __dirname);
+      macroConfig.setConfig(__filename, 'qunit', config);
+    });
+
+    test('throws for non-serializable config', () => {
+      let config = {
+        obj: {
+          regex: /regex/,
+        },
+      };
+
+      let macroConfig = MacrosConfig.for({}, __dirname);
+
+      expect(() => macroConfig.setConfig(__filename, 'qunit', config)).toThrow(
+        `[Embroider:MacrosConfig] the given config from '${__filename}' for packageName 'qunit' is not JSON serializable.`
+      );
+    });
+  });
+});