Add unit test for sending typing notification within 8 secs (Azure#19359)

Author: LuChen-Microsoft

sdk/communication/communication-chat/test/internal/chatThreadClient.mocked.spec.ts

@@ -344,6 +344,30 @@ describe("[Mocked] ChatThreadClient", async () => {
     assert.equal(request.method, "POST");
   });
 
+  it("makes only one sent typing notification request within 8 secs", async () => {
+    const mockHttpClient = generateHttpClient(400);
+    chatThreadClient = createChatThreadClient(threadId, mockHttpClient);
+    const spy = sinon.spy(mockHttpClient, "sendRequest");
+
+    try {
+      await chatThreadClient.sendTypingNotification();
+      assert.fail("Should have thrown an error");
+    } catch (e) {
+      assert.equal(e.statusCode, 400);
+    } finally {
+      const result = await chatThreadClient.sendTypingNotification();
+      assert.isFalse(result);
+
+      sinon.assert.calledOnce(spy);
+      const request = spy.getCall(0).args[0];
+      assert.equal(
+        request.url,
+        `${baseUri}/chat/threads/${threadId}/typing?api-version=${API_VERSION}`
+      );
+      assert.equal(request.method, "POST");
+    }
+  });
+
   it("makes successful sent typing notification request with sender display name", async () => {
     const mockHttpClient = generateHttpClient(200);
     chatThreadClient = createChatThreadClient(threadId, mockHttpClient);