Add automated tests for generated RPC code to restore JaCoCo coverage ≥85%

src/main/java/com/github/copilot/sdk/CopilotSession.java

@@ -542,9 +542,17 @@ public CompletableFuture<AssistantMessageEvent> sendAndWait(MessageOptions optio
             }
         }
 
-        // When inner future completes, run cleanup and propagate to result
+        // When inner future completes, run cleanup and propagate to result.
+        // Use whenCompleteAsync so that result.complete(r) is not called
+        // synchronously on the event-dispatch thread while dispatchEvent() is
+        // still iterating over handlers. Without async dispatch, a caller that
+        // registered its own session.on() listener before calling sendAndWait()
+        // could see its listener invoked *after* result.get() returned, because
+        // sendAndWait's internal handler would complete the future mid-loop. By
+        // submitting the completion to timeoutScheduler we allow the current
+        // dispatch loop to finish calling all other handlers first.
         final ScheduledFuture<?> taskToCancel = timeoutTask;
-        future.whenComplete((r, ex) -> {
+        future.whenCompleteAsync((r, ex) -> {
             try {
                 subscription.close();
             } catch (IOException e) {
@@ -560,7 +568,7 @@ public CompletableFuture<AssistantMessageEvent> sendAndWait(MessageOptions optio
                     result.complete(r);
                 }
             }
-        });
+        }, timeoutScheduler);
 
         // When result is cancelled externally, cancel inner future to trigger cleanup
         result.whenComplete((v, ex) -> {

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

@@ -10,13 +10,27 @@
 import java.nio.file.Paths;
 
 /**
- * Shared test utilities for locating the Copilot CLI binary.
+ * Shared test utilities for locating the Copilot CLI binary and other
+ * cross-platform test helpers.
  */
-final class TestUtil {
+public final class TestUtil {
 
     private TestUtil() {
     }
 
+    /**
+     * Returns a platform-independent path string for a file inside the system
+     * temporary directory. Uses {@code java.io.tmpdir} so tests run correctly on
+     * both POSIX and Windows.
+     *
+     * @param filename
+     *            the file name (no directory separator required)
+     * @return absolute path string in the system temp directory
+     */
+    public static String tempPath(String filename) {
+        return Path.of(System.getProperty("java.io.tmpdir"), filename).toString();
+    }
+
     /**
      * Locates a launchable Copilot CLI executable.
      * <p>