gh-116622: Android test script improvements (#124012)

* Set Android test script stdout to line-buffered
* Print warning logcat messages on stderr
* Add a -vv option to display high-volume messages which are rarely useful
* Documentation and comment improvements

1 files changed, 20 insertions, 5 deletions

diff --git a/Android/android.py b/Android/android.py
index bfa7832..8696d9e 100755
--- a/Android/android.py
+++ b/Android/android.py
@@ -259,8 +259,8 @@ def setup_testbed():
              f"{temp_dir}/{outer_jar}", "gradle-wrapper.jar"])
 
 
-# run_testbed will build the app automatically, but it hides the Gradle output
-# by default, so it's useful to have this as a separate command for the buildbot.
+# run_testbed will build the app automatically, but it's useful to have this as
+# a separate command to allow running the app outside of this script.
 def build_testbed(context):
     setup_sdk()
     setup_testbed()
@@ -376,6 +376,8 @@ async def find_pid(serial):
     shown_error = False
     while True:
         try:
+            # `pidof` requires API level 24 or higher. The level 23 emulator
+            # includes it, but it doesn't work (it returns all processes).
             pid = (await async_check_output(
                 adb, "-s", serial, "shell", "pidof", "-s", APP_ID
             )).strip()
@@ -407,6 +409,7 @@ async def logcat_task(context, initial_devices):
     serial = await wait_for(find_device(context, initial_devices), startup_timeout)
     pid = await wait_for(find_pid(serial), startup_timeout)
 
+    # `--pid` requires API level 24 or higher.
     args = [adb, "-s", serial, "logcat", "--pid", pid,  "--format", "tag"]
     hidden_output = []
     async with async_process(
@@ -421,11 +424,15 @@ async def logcat_task(context, initial_devices):
                 # such messages, but other components might.
                 level, message = None, line
 
+            # Exclude high-volume messages which are rarely useful.
+            if context.verbose < 2 and "from python test_syslog" in message:
+                continue
+
             # Put high-level messages on stderr so they're highlighted in the
             # buildbot logs. This will include Python's own stderr.
             stream = (
                 sys.stderr
-                if level in ["E", "F"]  # ERROR and FATAL (aka ASSERT)
+                if level in ["W", "E", "F"]  # WARNING, ERROR, FATAL (aka ASSERT)
                 else sys.stdout
             )
 
@@ -573,8 +580,9 @@ def parse_args():
     test = subcommands.add_parser(
         "test", help="Run the test suite")
     test.add_argument(
-        "-v", "--verbose", action="store_true",
-        help="Show Gradle output, and non-Python logcat messages")
+        "-v", "--verbose", action="count", default=0,
+        help="Show Gradle output, and non-Python logcat messages. "
+        "Use twice to include high-volume messages which are rarely useful.")
     device_group = test.add_mutually_exclusive_group(required=True)
     device_group.add_argument(
         "--connected", metavar="SERIAL", help="Run on a connected device. "
@@ -591,6 +599,13 @@ def parse_args():
 
 def main():
     install_signal_handler()
+
+    # Under the buildbot, stdout is not a TTY, but we must still flush after
+    # every line to make sure our output appears in the correct order relative
+    # to the output of our subprocesses.
+    for stream in [sys.stdout, sys.stderr]:
+        stream.reconfigure(line_buffering=True)
+
     context = parse_args()
     dispatch = {"configure-build": configure_build_python,
                 "make-build": make_build_python,