From 0a6beb1327e0c0be51f515b79b9c09f455601b75 Mon Sep 17 00:00:00 2001
From: Szymon Marczak <36894700+szmarczak@users.noreply.github.com>
Date: Fri, 26 Apr 2019 08:22:18 +0200
Subject: [PATCH] Fix `ky.extend()` not inheriting its parent and add
 `ky.create()` (#128)

---
 index.d.ts      |  9 +++++++++
 index.js        | 19 +++++++++++++------
 index.test-d.ts |  1 +
 readme.md       |  8 +++++++-
 test/main.js    | 50 ++++++++++++++++++++++++++++++++++++++++++-------
 5 files changed, 73 insertions(+), 14 deletions(-)

diff --git a/index.d.ts b/index.d.ts
index 5296a2d8..a3f06220 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -211,9 +211,18 @@ declare const ky: {
 	*/
 	delete(url: Request | URL | string, options?: Options): ResponsePromise;
 
+	/**
+	Create a new Ky instance with complete new defaults.
+
+	@returns A new Ky instance.
+	*/
+	create(defaultOptions: Options): typeof ky;
+
 	/**
 	Create a new Ky instance with some defaults overridden with your own.
 
+	In contrast to `ky.create()`, `ky.extend()` inherits defaults from its parent.
+
 	@returns A new Ky instance.
 	*/
 	extend(defaultOptions: Options): typeof ky;
diff --git a/index.js b/index.js
index ce286d4b..5ba083b2 100644
--- a/index.js
+++ b/index.js
@@ -313,18 +313,25 @@ class Ky {
 	}
 }
 
-const createInstance = (defaults = {}) => {
-	if (!isObject(defaults) || Array.isArray(defaults)) {
-		throw new TypeError('The `defaultOptions` argument must be an object');
+const validateAndMerge = (...sources) => {
+	for (const source of sources) {
+		if ((!isObject(source) || Array.isArray(source)) && typeof source !== 'undefined') {
+			throw new TypeError('The `options` argument must be an object');
+		}
 	}
 
-	const ky = (input, options) => new Ky(input, deepMerge({}, defaults, options));
+	return deepMerge({}, ...sources);
+};
+
+const createInstance = defaults => {
+	const ky = (input, options) => new Ky(input, validateAndMerge(defaults, options));
 
 	for (const method of requestMethods) {
-		ky[method] = (input, options) => new Ky(input, deepMerge({}, defaults, options, {method}));
+		ky[method] = (input, options) => new Ky(input, validateAndMerge(defaults, options, {method}));
 	}
 
-	ky.extend = defaults => createInstance(defaults);
+	ky.create = newDefaults => createInstance(validateAndMerge(newDefaults));
+	ky.extend = newDefaults => createInstance(validateAndMerge(defaults, newDefaults));
 
 	return ky;
 };
diff --git a/index.test-d.ts b/index.test-d.ts
index 5cfb3313..3cc39061 100644
--- a/index.test-d.ts
+++ b/index.test-d.ts
@@ -35,6 +35,7 @@ for (const method of requestBodyMethods) {
 	expectType<ResponsePromise>(ky[method as RequestBodyMethod](url, {body: 'x'}));
 }
 
+expectType<typeof ky>(ky.create({}));
 expectType<typeof ky>(ky.extend({}));
 expectType<HTTPError>(new HTTPError(new Response));
 expectType<TimeoutError>(new TimeoutError);
diff --git a/readme.md b/readme.md
index 6b575a5d..92b5d351 100644
--- a/readme.md
+++ b/readme.md
@@ -246,12 +246,18 @@ Setting this to `false` may be useful if you are checking for resource availabil
 
 Create a new `ky` instance with some defaults overridden with your own.
 
+In contrast to `ky.create()`, `ky.extend()` inherits defaults from its parent.
+
+### ky.create(defaultOptions)
+
+Create a new Ky instance with complete new defaults.
+
 ```js
 import ky from 'ky';
 
 // On https://my-site.com
 
-const api = ky.extend({prefixUrl: 'https://example.com/api'});
+const api = ky.create({prefixUrl: 'https://example.com/api'});
 
 (async () => {
 	await api.get('users/123');
diff --git a/test/main.js b/test/main.js
index ed3a017c..22c532c0 100644
--- a/test/main.js
+++ b/test/main.js
@@ -258,13 +258,13 @@ test('throwHttpErrors option with POST', async t => {
 	await server.close();
 });
 
-test('ky.extend()', async t => {
+test('ky.create()', async t => {
 	const server = await createTestServer();
 	server.get('/', (request, response) => {
 		response.end(`${request.headers.unicorn} - ${request.headers.rainbow}`);
 	});
 
-	const extended = ky.extend({
+	const extended = ky.create({
 		headers: {
 			rainbow: 'rainbow'
 		}
@@ -284,7 +284,7 @@ test('ky.extend()', async t => {
 	await server.close();
 });
 
-test('ky.extend() throws when given non-object argument', t => {
+test('ky.create() throws when given non-object argument', t => {
 	const nonObjectValues = [
 		true,
 		666,
@@ -297,15 +297,15 @@ test('ky.extend() throws when given non-object argument', t => {
 
 	for (const value of nonObjectValues) {
 		t.throws(() => {
-			ky.extend(value);
+			ky.create(value);
 		}, {
 			instanceOf: TypeError,
-			message: 'The `defaultOptions` argument must be an object'
+			message: 'The `options` argument must be an object'
 		});
 	}
 });
 
-test('ky.extend() with deep array', async t => {
+test('ky.create() with deep array', async t => {
 	const server = await createTestServer();
 	server.get('/', (request, response) => {
 		response.end();
@@ -314,7 +314,7 @@ test('ky.extend() with deep array', async t => {
 	let isOriginBeforeRequestTrigged = false;
 	let isExtendBeforeRequestTrigged = false;
 
-	const extended = ky.extend({
+	const extended = ky.create({
 		hooks: {
 			beforeRequest: [
 				() => {
@@ -341,6 +341,42 @@ test('ky.extend() with deep array', async t => {
 	await server.close();
 });
 
+test('ky.extend()', async t => {
+	const server = await createTestServer();
+	server.get('/', (request, response) => {
+		response.end();
+	});
+
+	let isOriginBeforeRequestTrigged = false;
+	let isExtendBeforeRequestTrigged = false;
+
+	const extended = ky.extend({
+		hooks: {
+			beforeRequest: [
+				() => {
+					isOriginBeforeRequestTrigged = true;
+				}
+			]
+		}
+	}).extend({
+		hooks: {
+			beforeRequest: [
+				() => {
+					isExtendBeforeRequestTrigged = true;
+				}
+			]
+		}
+	});
+
+	await extended(server.url);
+
+	t.is(isOriginBeforeRequestTrigged, true);
+	t.is(isExtendBeforeRequestTrigged, true);
+	t.true((await extended.head(server.url)).ok);
+
+	await server.close();
+});
+
 test('throws AbortError when aborted by user', async t => {
 	const server = await createTestServer();
 	server.get('/', () => {});