Android GTest Runner: Create flags & test list files only when required

build/android/pylib/local/device/local_device_gtest_run.py

Index: build/android/pylib/local/device/local_device_gtest_run.py
diff --git a/build/android/pylib/local/device/local_device_gtest_run.py b/build/android/pylib/local/device/local_device_gtest_run.py
index caef0548d2daf93f7dc392449f7d935df0851632..4413e84b0dde28ee986f3648a05bfc55b8182bd1 100644
--- a/build/android/pylib/local/device/local_device_gtest_run.py
+++ b/build/android/pylib/local/device/local_device_gtest_run.py
@@ -19,6 +19,7 @@ from pylib.local.device import local_device_test_run
 
 _COMMAND_LINE_FLAGS_SUPPORTED = True
 
+_MAX_INLINE_FLAGS_LENGTH = 50  # Arbitrarily chosen.
 _EXTRA_COMMAND_LINE_FILE = (
     'org.chromium.native_test.NativeTestActivity.CommandLineFile')
 _EXTRA_COMMAND_LINE_FLAGS = (
@@ -26,6 +27,9 @@ _EXTRA_COMMAND_LINE_FLAGS = (
 _EXTRA_TEST_LIST = (
     'org.chromium.native_test.NativeTestInstrumentationTestRunner'
         '.TestList')
+_EXTRA_TEST = (
+    'org.chromium.native_test.NativeTestInstrumentationTestRunner'
+        '.Test')
 
 _MAX_SHARD_SIZE = 256
 _SECONDS_TO_NANOS = int(1e9)
@@ -121,21 +125,35 @@ class _ApkDelegate(object):
       extras[gtest_test_instance.EXTRA_SHARD_NANO_TIMEOUT] = int(
           kwargs['timeout'] * _SECONDS_TO_NANOS)
 
-    with device_temp_file.DeviceTempFile(device.adb) as command_line_file:
-      device.WriteFile(command_line_file.name, '_ %s' % flags if flags else '_')
-      extras[_EXTRA_COMMAND_LINE_FILE] = command_line_file.name
-
-      with device_temp_file.DeviceTempFile(device.adb) as test_list_file:
-        if test:
-          device.WriteFile(test_list_file.name, '\n'.join(test))
-          extras[_EXTRA_TEST_LIST] = test_list_file.name
-
-        try:
-          return device.StartInstrumentation(
-              self._component, extras=extras, raw=False, **kwargs)
-        except Exception:
-          device.ForceStop(self._package)
-          raise
+    command_line_file = None

[jbudorick, 2015/10/20 17:41:23]

I'll be honest, this is a lot messier than the previous version :(

It would be nice to be able to continue using DeviceTempFile as a context
manager, though doing so would involving writing a some sort of conditional
context manager that does X or Y depending on some condition Z.

[agrieve, 2015/10/20 18:36:55]

Did some googling and came up with:
https://docs.python.org/3/library/contextlib.html#simplifying-support-for-sin...
(full background: http://bugs.python.org/issue10049)

Sadly, we're not using python3, so added a no-op context manager as a private
helper.

+    if flags:
+      if len(flags) > _MAX_INLINE_FLAGS_LENGTH:
+        command_line_file = device_temp_file.DeviceTempFile(device.adb)
+        device.WriteFile(command_line_file.name, '_ %s' % flags)
+        extras[_EXTRA_COMMAND_LINE_FILE] = command_line_file.name
+      else:
+        extras[_EXTRA_COMMAND_LINE_FLAGS] = flags
+
+    test_list_file = None
+    if test:
+      if len(test) > 1:
+        test_list_file = device_temp_file.DeviceTempFile(device.adb)
+        device.WriteFile(test_list_file.name, '\n'.join(test))
+        extras[_EXTRA_TEST_LIST] = test_list_file.name
+      else:
+        extras[_EXTRA_TEST] = test[0]
+
+    try:
+      return device.StartInstrumentation(
+          self._component, extras=extras, raw=False, **kwargs)
+    except Exception:
+      device.ForceStop(self._package)
+      raise
+    finally:
+      if command_line_file:
+        command_line_file.close()
+      if test_list_file:
+        test_list_file.close()
 
   def PullAppFiles(self, device, files, directory):
     PullAppFilesImpl(device, self._package, files, directory)