feat: add partitioned option (#21)

* feat: partitioned cookies

* test: partitioned cookies

* fix: run lint:fix

* lint

* sync docs with @types/cookie

---------

Co-authored-by: Pooya Parsa <pooya@pi0.io>

src/index.ts

@@ -197,6 +197,10 @@ export function serialize(
     }
   }
 
+  if (opt.partitioned) {
+    str += "; Partitioned";
+  }
+
   return str;
 }
 

src/types.ts

@@ -108,6 +108,17 @@ export interface CookieSerializeOptions {
    * not have an HTTPS connection.
    */
   secure?: boolean | undefined;
+  /**
+   * Specifies the `boolean` value for the [`Partitioned` `Set-Cookie`](rfc-cutler-httpbis-partitioned-cookies)
+   * attribute. When truthy, the `Partitioned` attribute is set, otherwise it is not. By default, the
+   * `Partitioned` attribute is not set.
+   *
+   * **note** This is an attribute that has not yet been fully standardized, and may change in the future.
+   * This also means many clients may ignore this attribute until they understand it.
+   *
+   * More information about can be found in [the proposal](https://github.com/privacycg/CHIPS)
+   */
+  partitioned?: boolean;
 }
 
 /**

test/serialize.test.ts

@@ -261,4 +261,16 @@ describe("serialize(name, value, options)", () => {
       expect(serialize("foo", "bar", { secure: false })).toBe("foo=bar");
     });
   });
+
+  describe('with "partitioned" option', () => {
+    it("should include partitioned flag when true", () => {
+      expect(serialize("foo", "bar", { partitioned: true })).toBe(
+        "foo=bar; Partitioned",
+      );
+    });
+
+    it("should not include partitioned flag when false", () => {
+      expect(serialize("foo", "bar", { partitioned: false })).toBe("foo=bar");
+    });
+  });
 });