desktop_tester.py: some random improvements to help with debugging failed runs

scripts/gha/desktop_tester.py

@@ -26,7 +26,9 @@
 
 import os
 import platform
+import shlex
 import subprocess
+import time
 import threading
 
 from absl import app
@@ -104,28 +106,40 @@ class Test(object):
   # them as fields so they can be accessed from the main thread.
   def run(self):
     """Executes this testapp."""
-    result = None  # Ensures this var is defined if timeout occurs.
     os.chmod(self.testapp_path, 0o777)
+    args = list(shlex.split(FLAGS.cmd_prefix)) + [self.testapp_path]
+    args_str = subprocess.list2cmdline(args)
+    logging.info("Test starting: %s", args_str)
+    start_time_secs = time.monotonic()
     try:
       result = subprocess.run(
-          args=FLAGS.cmd_prefix.split() + [self.testapp_path],
+          args=args,
           cwd=os.path.dirname(self.testapp_path),  # Testapp uses CWD for config
           stdout=subprocess.PIPE,
           stderr=subprocess.STDOUT,
           text=True,
+          errors="replace",
           check=False,
           timeout=900)
     except subprocess.TimeoutExpired as e:
-      logging.error("Testapp timed out!")
+      logging.error("Testapp timed out: %s", args_str)
       # e.output will sometimes be bytes, sometimes string. Decode if needed.
       try:
         self.logs = e.output.decode()
       except AttributeError:  # This will happen if it's already a string.
         self.logs = e.output
-    if result:
+    else:
       self.logs = result.stdout
-      logging.info("Test result: %s", self.logs)
-    logging.info("Finished running %s", self.testapp_path)
+      logging.info(
+        "Test result of %s (exit code: %s): %s",
+        args_str, result.returncode, self.logs)
+
+    end_time_secs = time.monotonic()
+    elapsed_time_secs = end_time_secs - start_time_secs
+    elapsed_time_str = f"{elapsed_time_secs/60:.2f} minutes"
+    logging.info(
+      "Test completed (elapsed time: %s): %s",
+      elapsed_time_str, args_str)
 
 
 if __name__ == "__main__":