CopyTest: use CountDownLatch via WireMock post-serve action instead of polling

Co-authored-by: brendandburns <5751682+brendandburns@users.noreply.github.com>

Author: Copilot

util/src/test/java/io/kubernetes/client/CopyTest.java

@@ -19,8 +19,12 @@
 import static com.github.tomakehurst.wiremock.client.WireMock.urlPathEqualTo;
 import static com.github.tomakehurst.wiremock.core.WireMockConfiguration.wireMockConfig;
 
+import com.github.tomakehurst.wiremock.core.Admin;
+import com.github.tomakehurst.wiremock.extension.Parameters;
+import com.github.tomakehurst.wiremock.extension.PostServeAction;
 import com.github.tomakehurst.wiremock.junit5.WireMockExtension;
 import com.github.tomakehurst.wiremock.matching.AnythingPattern;
+import com.github.tomakehurst.wiremock.stubbing.ServeEvent;
 import io.kubernetes.client.openapi.ApiClient;
 import io.kubernetes.client.openapi.ApiException;
 import io.kubernetes.client.openapi.models.V1ObjectMeta;
@@ -36,6 +40,8 @@
 import java.nio.file.Paths;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.RegisterExtension;
@@ -119,9 +125,24 @@ public InputStream copyFileFromPod(String namespace, String pod, String srcPath)
     }
   }
 
+  public static class CountDownLatchAction extends PostServeAction {
+    @Override
+    public String getName() {
+      return "countdown";
+    }
+
+    @Override
+    public void doAction(ServeEvent serveEvent, Admin admin, Parameters parameters) {
+      CountDownLatch latch = (CountDownLatch) parameters.get("latch");
+      latch.countDown();
+    }
+  }
+
   @RegisterExtension
   static WireMockExtension apiServer =
-      WireMockExtension.newInstance().options(wireMockConfig().dynamicPort()).build();
+      WireMockExtension.newInstance()
+          .options(wireMockConfig().dynamicPort().extensions(new CountDownLatchAction()))
+          .build();
 
   @BeforeEach
   void setup() {
@@ -131,21 +152,6 @@ void setup() {
     podName = "apod";
   }
 
-  // Wait (bounded) until the exec request reaches the mock server, instead of a fixed sleep
-  // which is flaky on slow CI runners.
-  private void waitForExecRequest() throws InterruptedException {
-    long deadline = System.currentTimeMillis() + 30000;
-    while (System.currentTimeMillis() < deadline
-        && apiServer
-            .findAll(
-                getRequestedFor(
-                    urlPathEqualTo(
-                        "/api/v1/namespaces/" + namespace + "/pods/" + podName + "/exec")))
-            .isEmpty()) {
-      Thread.sleep(100);
-    }
-  }
-
   @Test
   void url() {
     Copy copy = new Copy(client);
@@ -186,8 +192,13 @@ void copyFileToPod(@TempDir Path tempDir) throws Exception {
 
     Copy copy = new Copy(client);
 
+    CountDownLatch latch = new CountDownLatch(1);
+    Parameters params = new Parameters();
+    params.put("latch", latch);
+
     apiServer.stubFor(
         get(urlPathEqualTo("/api/v1/namespaces/" + namespace + "/pods/" + podName + "/exec"))
+            .withPostServeAction("countdown", params)
             .willReturn(
                 aResponse()
                     .withStatus(404)
@@ -210,7 +221,7 @@ public void run() {
               }
             });
     t.start();
-    waitForExecRequest();
+    assertTrue(latch.await(30, TimeUnit.SECONDS));
     t.interrupt();
 
     apiServer.verify(
@@ -232,8 +243,13 @@ void copyBinaryDataToPod() throws InterruptedException {
 
     Copy copy = new Copy(client);
 
+    CountDownLatch latch = new CountDownLatch(1);
+    Parameters params = new Parameters();
+    params.put("latch", latch);
+
     apiServer.stubFor(
         get(urlPathEqualTo("/api/v1/namespaces/" + namespace + "/pods/" + podName + "/exec"))
+            .withPostServeAction("countdown", params)
             .willReturn(
                 aResponse()
                     .withStatus(404)
@@ -256,7 +272,7 @@ public void run() {
               }
             });
     t.start();
-    waitForExecRequest();
+    assertTrue(latch.await(30, TimeUnit.SECONDS));
     t.interrupt();
 
     apiServer.verify(
@@ -275,8 +291,13 @@ public void run() {
   void testCopyDirectoryFromPod(@TempDir Path tempDir) throws Exception {
     Copy copy = new Copy(client);
 
+    CountDownLatch latch = new CountDownLatch(1);
+    Parameters params = new Parameters();
+    params.put("latch", latch);
+
     apiServer.stubFor(
         get(urlPathEqualTo("/api/v1/namespaces/" + namespace + "/pods/" + podName + "/exec"))
+            .withPostServeAction("countdown", params)
             .willReturn(
                 aResponse()
                     .withStatus(404)
@@ -300,7 +321,7 @@ public void run() {
               }
             });
     t.start();
-    waitForExecRequest();
+    assertTrue(latch.await(30, TimeUnit.SECONDS));
     t.interrupt();
 
     apiServer.verify(