fix: merge objects with Module type (#121)

Co-authored-by: Pooya Parsa <pooya@pi0.io>

src/_utils.ts

@@ -14,9 +14,13 @@ export function isPlainObject(value: unknown): boolean {
     return false;
   }
 
-  if (Symbol.toStringTag in value || Symbol.iterator in value) {
+  if (Symbol.iterator in value) {
     return false;
   }
 
+  if (Symbol.toStringTag in value) {
+    return Object.prototype.toString.call(value) === "[object Module]";
+  }
+
   return true;
 }

test/defu.test.ts

@@ -1,6 +1,7 @@
 import { expectTypeOf } from "expect-type";
 import { it, describe, expect } from "vitest";
 import { defu, createDefu, defuFn, defuArrayFn } from "../src/defu";
+import * as asteriskImport from "./fixtures/";
 
 // Part of tests brought from jonschlinkert/defaults-deep (MIT)
 const nonObject = [null, undefined, [], false, true, 123];
@@ -232,4 +233,21 @@ describe("defu", () => {
       foo: { bar: { modules: "foo.bar:X,Y" } },
     });
   });
+
+  it("works with asterisk-import", () => {
+    expect(
+      defu(asteriskImport, {
+        a: 2,
+        exp: {
+          anotherNested: 2,
+        },
+      }),
+    ).toStrictEqual({
+      a: 2,
+      exp: {
+        anotherNested: 2,
+        nested: 1,
+      },
+    });
+  });
 });

test/fixtures/index.ts

@@ -0,0 +1 @@
+export { default as exp } from "./nested.js";

test/fixtures/nested.ts

@@ -0,0 +1,3 @@
+export default {
+  nested: 1,
+};