feat: [capricorn86#1315] Fixed handling of empty characters in headers

packages/happy-dom/src/fetch/Headers.ts

@@ -74,7 +74,7 @@ export default class Headers implements IHeaders {
 	 * @returns Value.
 	 */
 	public get(name: string): string | null {
-		return this[PropertySymbol.entries][name.toLowerCase()]?.value || null;
+		return this[PropertySymbol.entries][name.toLowerCase()]?.value ?? null;
 	}
 
 	/**
@@ -96,7 +96,13 @@ export default class Headers implements IHeaders {
 	 * @returns An array of strings representing the values of all the different Set-Cookie headers.
 	 */
 	public getSetCookie(): string[] {
-		return CookieStringUtility.splitCookiesString(this.get('Set-Cookie') || '');
+		const cookiesString = this.get('Set-Cookie');
+		if (cookiesString === null) {
+			return [];
+		} else if (cookiesString === '') {
+			return [''];
+		}
+		return CookieStringUtility.splitCookiesString(cookiesString);
 	}
 
 	/**

packages/happy-dom/test/fetch/Headers.test.ts

@@ -76,6 +76,14 @@ describe('Headers', () => {
 
 				expect(headers.get('Content-Type')).toBe('application/json, x-www-form-urlencoded');
 			});
+
+			it('Returns the value of Header as it is, set with an empty string.', () => {
+				const headers = new Headers();
+
+				headers.append('X-A', '');
+
+				expect(headers.get('X-A')).toBe('');
+			});
 		});
 
 		describe('set()', () => {
@@ -106,6 +114,13 @@ describe('Headers', () => {
 				expect(headers.getSetCookie()).toEqual([]);
 			});
 
+			it('Returns as a list of empty characters if the Set-Cookie header is set to an empty string.', () => {
+				const headers = new Headers();
+				headers.append('Set-Cookie', '');
+
+				expect(headers.getSetCookie()).toEqual(['']);
+			});
+
 			it('Returns an array of strings representing the values of all the different Set-Cookie headers.', () => {
 				const headers = new Headers();