Test: replace external blocking processes

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: edburns

java/sdk/src/test/java/com/github/copilot/CliServerManagerTest.java

@@ -70,19 +70,13 @@ void connectToServerTcpMode() throws Exception {
         }
     }
 
-    private static Process startBlockingProcess() throws IOException {
-        boolean isWindows = System.getProperty("os.name").toLowerCase().contains("windows");
-        return (isWindows ? new ProcessBuilder(System.getenv("COMSPEC"), "/c", "more") : new ProcessBuilder("cat"))
-                .start();
-    }
-
     @Test
     void connectToServerStdioMode() throws Exception {
         var options = new CopilotClientOptions();
         var manager = new CliServerManager(options);
 
         // Create a dummy process for stdio mode
-        Process process = startBlockingProcess();
+        Process process = new TestProcess();
         try {
             JsonRpcClient client = manager.connectToServer(process, null, null);
             assertNotNull(client);

java/sdk/src/test/java/com/github/copilot/JsonRpcClientTest.java

@@ -133,23 +133,17 @@ void testIsConnectedWithSocketClosed() throws Exception {
         pair.serverSocket.close();
     }
 
-    private static Process startBlockingProcess() throws IOException {
-        boolean isWindows = System.getProperty("os.name").toLowerCase().contains("windows");
-        return (isWindows ? new ProcessBuilder(System.getenv("COMSPEC"), "/c", "more") : new ProcessBuilder("cat"))
-                .start();
-    }
-
     @Test
     void testIsConnectedWithProcess() throws Exception {
-        Process proc = startBlockingProcess();
+        Process proc = new TestProcess();
         try (var client = JsonRpcClient.fromProcess(proc)) {
             assertTrue(client.isConnected());
         }
     }
 
     @Test
     void testIsConnectedWithProcessDead() throws Exception {
-        Process proc = startBlockingProcess();
+        Process proc = new TestProcess();
         var client = JsonRpcClient.fromProcess(proc);
         proc.destroy();
         proc.waitFor(5, TimeUnit.SECONDS);
@@ -161,7 +155,7 @@ void testIsConnectedWithProcessDead() throws Exception {
 
     @Test
     void testGetProcessReturnsProcess() throws Exception {
-        Process proc = startBlockingProcess();
+        Process proc = new TestProcess();
         try (var client = JsonRpcClient.fromProcess(proc)) {
             assertSame(proc, client.getProcess());
         }

java/sdk/src/test/java/com/github/copilot/TestProcess.java

@@ -0,0 +1,65 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *--------------------------------------------------------------------------------------------*/
+
+package com.github.copilot;
+
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+
+final class TestProcess extends Process {
+
+    private final CountDownLatch terminated = new CountDownLatch(1);
+
+    @Override
+    public OutputStream getOutputStream() {
+        return OutputStream.nullOutputStream();
+    }
+
+    @Override
+    public InputStream getInputStream() {
+        return InputStream.nullInputStream();
+    }
+
+    @Override
+    public InputStream getErrorStream() {
+        return InputStream.nullInputStream();
+    }
+
+    @Override
+    public int waitFor() throws InterruptedException {
+        terminated.await();
+        return 0;
+    }
+
+    @Override
+    public boolean waitFor(long timeout, TimeUnit unit) throws InterruptedException {
+        return terminated.await(timeout, unit);
+    }
+
+    @Override
+    public int exitValue() {
+        if (isAlive()) {
+            throw new IllegalThreadStateException("Process has not exited");
+        }
+        return 0;
+    }
+
+    @Override
+    public void destroy() {
+        terminated.countDown();
+    }
+
+    @Override
+    public Process destroyForcibly() {
+        destroy();
+        return this;
+    }
+
+    @Override
+    public boolean isAlive() {
+        return terminated.getCount() > 0;
+    }
+}