fix: align certificate types and close gathering state

docs/divergences.md

@@ -78,6 +78,9 @@ rejects `setConfiguration()` calls that change the certificate set, and passes
 the first configured certificate into libdatachannel's `rtc::Configuration` so
 the generated DTLS fingerprint appears in local SDP.
 
+Certificate generation supports object-form ECDSA P-256 and RSA SHA-256
+algorithms. String-form WebCrypto `AlgorithmIdentifier` values are rejected.
+
 libdatachannel accepts one certificate/key pair for a peer connection. The W3C
 configuration dictionary allows a sequence of certificates, and WPT has a case
 that expects all configured certificate fingerprints to appear in SDP. The

index.d.ts

@@ -280,9 +280,7 @@ export class RTCSctpTransport extends EventTarget {
 }
 
 export class RTCPeerConnection extends EventTarget {
-  static generateCertificate(
-    algorithm: string | RTCCertificateKeygenAlgorithm,
-  ): Promise<RTCCertificate>;
+  static generateCertificate(algorithm: RTCCertificateKeygenAlgorithm): Promise<RTCCertificate>;
   constructor(configuration?: RTCConfiguration);
   readonly localDescription: RTCSessionDescription | null;
   readonly currentLocalDescription: RTCSessionDescription | null;

lib/index.js

@@ -3369,6 +3369,7 @@ class RTCPeerConnection extends SimpleEventTarget {
     });
     this._connectionState = "closed";
     this._iceConnectionState = "closed";
+    this._iceGatheringState = "new";
     this._deferredIceEvents = [];
     this._preparedLocalDescription = null;
     this._nonstandardPreparedLocalDescriptionType = null;

test/basic.test.js

@@ -615,6 +615,22 @@ test("generateCertificate returns a native-backed RTCCertificate", async (t) =>
   pc.close();
 });
 
+test("generateCertificate rejects string-form algorithms", async () => {
+  await assert.rejects(
+    RTCPeerConnection.generateCertificate("ECDSA"),
+    (error) => error.name === "NotSupportedError",
+  );
+});
+
+test("close resets iceGatheringState to new", () => {
+  const pc = new RTCPeerConnection();
+
+  pc._iceGatheringState = "complete";
+  pc.close();
+
+  assert.equal(pc.iceGatheringState, "new");
+});
+
 test("createDataChannel rejects duplicate negotiated ids until the channel closes", async (t) => {
   const pc = new RTCPeerConnection();
   t.after(() => closeAllAndWait(pc));

test/types.ts

@@ -54,6 +54,8 @@ const certificatePromise: Promise<RTCCertificate> = RTCPeerConnection.generateCe
   namedCurve: "P-256",
   expires: 60000,
 });
+// @ts-expect-error string-form certificate algorithms are not supported.
+RTCPeerConnection.generateCertificate("ECDSA");
 const pc = new RTCPeerConnection();
 pc.setConfiguration({ iceServers: [{ urls: "stun:stun.example.org" }], iceCandidatePoolSize: 0 });
 const configuration = pc.getConfiguration();