refactor: move isPlainObject to _utils to allow testing

Author: pi0

src/_utils.ts

@@ -0,0 +1,16 @@
+// From sindresorhus/is-plain-obj
+// MIT License
+// Copyright (c) Sindre Sorhus <sindresorhus@gmail.com> (https://sindresorhus.com)
+export function isPlainObject(value: unknown): boolean {
+ if (value === null || typeof value !== "object") {
+ return false;
+ }
+ const prototype = Object.getPrototypeOf(value);
+ return (
+ (prototype === null ||
+ prototype === Object.prototype ||
+ Object.getPrototypeOf(prototype) === null) &&
+ !(Symbol.toStringTag in value) &&
+ !(Symbol.iterator in value)
+ );
+}

src/defu.ts

@@ -1,3 +1,4 @@
+import { isPlainObject } from "./_utils";
 import type { Merger, DefuFn as DefuFunction, DefuInstance } from "./types";
 
 // Base function to apply defaults
@@ -7,7 +8,7 @@ function _defu<T>(
  namespace = ".",
  merger?: Merger,
 ): T {
- if (!_isPlainObject(defaults)) {
+ if (!isPlainObject(defaults)) {
  return _defu(baseObject, {}, namespace, merger);
  }
 
@@ -30,7 +31,7 @@ function _defu<T>(
 
  if (Array.isArray(value) && Array.isArray(object[key])) {
  object[key] = [...value, ...object[key]];
- } else if (_isPlainObject(value) && _isPlainObject(object[key])) {
+ } else if (isPlainObject(value) && isPlainObject(object[key])) {
  object[key] = _defu(
  value,
  object[key],
@@ -45,23 +46,6 @@ function _defu<T>(
  return object;
 }
 
-// From sindresorhus/is-plain-obj
-// MIT License
-// Copyright (c) Sindre Sorhus <sindresorhus@gmail.com> (https://sindresorhus.com)
-function _isPlainObject(value: unknown): boolean {
- if (value === null || typeof value !== "object") {
- return false;
- }
- const prototype = Object.getPrototypeOf(value);
- return (
- (prototype === null ||
- prototype === Object.prototype ||
- Object.getPrototypeOf(prototype) === null) &&
- !(Symbol.toStringTag in value) &&
- !(Symbol.iterator in value)
- );
-}
-
 // Create defu wrapper with optional merger and multi arg support
 export function createDefu(merger?: Merger): DefuFunction {
  return (...arguments_) =>