Add parsePackage method, bump dependencies, target Node 16

index.js

@@ -15,7 +15,7 @@ const getPackagePath = cwd => {
 const _readPackage = (file, normalize) => {
 	const json = typeof file === 'string'
 		? parseJson(file)
-		: file; // TODO: ensure `file` is an object here
+		: file;
 
 	if (normalize) {
 		normalizePackageData(json);
@@ -35,5 +35,19 @@ export function readPackageSync({cwd, normalize = true} = {}) {
 }
 
 export function parsePackage(packageFile, {normalize = true} = {}) {
-	return _readPackage(packageFile, normalize);
+	const isObject = packageFile !== null && typeof packageFile === 'object' && !Array.isArray(packageFile);
+	const isString = typeof packageFile === 'string';
+
+	if (!isObject && !isString) {
+		throw new TypeError('`packageFile` should be either an `object` or a `string`.');
+	}
+
+	// Input should not be modified - if `structuredClone` is available, do a deep clone, shallow otherwise
+	const clonedPackageFile = isObject
+		? (structuredClone === undefined
+			? {...packageFile}
+			: structuredClone(packageFile))
+		: packageFile;
+
+	return _readPackage(clonedPackageFile, normalize);
 }

package.json

@@ -43,10 +43,5 @@
 		"ava": "^5.2.0",
 		"tsd": "^0.28.1",
 		"xo": "^0.54.0"
-	},
-	"xo": {
-		"ignores": [
-			"test/test.js"
-		]
 	}
 }

readme.md

@@ -57,6 +57,8 @@ Default: `true`
 
 Parses an object or string into JSON.
 
+Note: `packageFile` is cloned using [`structuredClone`](https://developer.mozilla.org/en-US/docs/Web/API/structuredClone) to prevent modification to the input object. In environments without `structuredClone`, a shallow spread is used instead, which can cause deep properties of the object to be modified. Consider cloning the object before using `parsePackage` if that's the case.
+
 #### packageFile
 
 Type: `object | string`\

test/test.js

@@ -41,7 +41,7 @@
 	);
 });
 
 test('sync - normalize option', async t => {
 	const package_ = readPackageSync({normalize: false});
 	t.is(package_.name, 'unicorn ');
 });
@@ -53,7 +53,7 @@
 };
 
 test('parsePackage - json input', t => {
-	const package_ = parsePackage({...pkgJson});
+	const package_ = parsePackage(pkgJson);
 	t.is(package_.name, 'unicorn');
 	t.deepEqual(
 		readPackageSync(),
@@ -71,10 +71,34 @@
 });
 
 test('parsePackage - normalize option', t => {
-	const package_ = parsePackage({...pkgJson}, {normalize: false});
+	const package_ = parsePackage(pkgJson, {normalize: false});
 	t.is(package_.name, 'unicorn ');
 	t.deepEqual(
 		readPackageSync({normalize: false}),
 		package_,
 	);
 });
+
+test('parsePackage - errors on invalid input', t => {
+	t.throws(
+		() => parsePackage(['foo', 'bar']),
+		{message: '`packageFile` should be either an `object` or a `string`.'},
+	);
+
+	t.throws(
+		() => parsePackage(null),
+		{message: '`packageFile` should be either an `object` or a `string`.'},
+	);
+
+	t.throws(
+		() => parsePackage(() => ({name: 'unicorn'})),
+		{message: '`packageFile` should be either an `object` or a `string`.'},
+	);
+});
+
+test('parsePackage - does not modify source object', t => {
+	const pkgObject = {name: 'unicorn', version: '1.0.0'};
+	const package_ = parsePackage(pkgObject);
+
+	t.not(pkgObject, package_);
+});