fix(Request): support custom "credentials" value

packages/fetch/src/request.js

@@ -37,6 +37,7 @@ const isRequest = object => {
  * @property {string} method
  * @property {RequestRedirect} redirect
  * @property {globalThis.Headers} headers
+ * @property {RequestCredentials} credentials
  * @property {URL} parsedURL
  * @property {AbortSignal|null} signal
  * 
@@ -125,6 +126,7 @@ export default class Request extends Body {
 			method,
 			redirect: init.redirect || input.redirect || 'follow',
 			headers,
+			credentials: init.credentials || 'same-origin',
 			parsedURL,
 			signal: signal || null
 		};
@@ -159,7 +161,7 @@ export default class Request extends Body {
 	 */
 
 	get credentials() {
-		return "same-origin"
+		return this[INTERNALS].credentials
 	}
 
 	/**

packages/fetch/test/request.js

@@ -132,6 +132,16 @@ describe('Request', () => {
 		expect(clonedRequest.signal.aborted).to.equal(true);
 	});
 
+	it('should default to "same-origin" as credentials', () => {
+		const request = new Request(base)
+		expect(request.credentials).to.equal('same-origin');
+	})
+
+	it('should respect custom credentials value', () => {
+		expect(new Request(base, { credentials: 'omit'})).to.have.property('credentials', 'omit');
+		expect(new Request(base, { credentials: 'include'})).to.have.property('credentials', 'include');
+	})
+
 	it('should throw error with GET/HEAD requests with body', () => {
 		expect(() => new Request(base, {body: ''}))
 			.to.throw(TypeError);