Add test for log file trimming

Also change root for test_log_file_names tests to be
a temporary directory to allow runnig tests without sudo.
The old root `/` or `C:` is not usually writable for regular users.

Author: Somsikov, Andrey

gtest_parallel_tests.py

@@ -311,36 +311,42 @@ def test_times_worker():
 
 class TestTask(unittest.TestCase):
   def test_log_file_names(self):
-    def root():
-      return 'C:\\' if sys.platform == 'win32' else '/'
-
-    self.assertEqual(
-      os.path.join('.', 'bin-Test_case-100.log'),
-      gtest_parallel.Task._logname('.', 'bin', 'Test.case', 100))
-
-    self.assertEqual(
-      os.path.join('..', 'a', 'b', 'bin-Test_case_2-1.log'),
-      gtest_parallel.Task._logname(os.path.join('..', 'a', 'b'),
-                                   os.path.join('..', 'bin'),
-                                   'Test.case/2', 1))
-
-    self.assertEqual(
-      os.path.join('..', 'a', 'b', 'bin-Test_case_2-5.log'),
-      gtest_parallel.Task._logname(os.path.join('..', 'a', 'b'),
-                                   os.path.join(root(), 'c', 'd', 'bin'),
-                                   'Test.case/2', 5))
-
-    self.assertEqual(
-      os.path.join(root(), 'a', 'b', 'bin-Instantiation_Test_case_2-3.log'),
-      gtest_parallel.Task._logname(os.path.join(root(), 'a', 'b'),
-                                   os.path.join('..', 'c', 'bin'),
-                                   'Instantiation/Test.case/2', 3))
-
-    self.assertEqual(
-      os.path.join(root(), 'a', 'b', 'bin-Test_case-1.log'),
-      gtest_parallel.Task._logname(os.path.join(root(), 'a', 'b'),
-                                   os.path.join(root(), 'c', 'd', 'bin'),
-                                   'Test.case', 1))
+    with tempfile.TemporaryDirectory() as root:
+      self.assertEqual(
+        os.path.join('.', 'bin-Test_case-100.log'),
+        gtest_parallel.Task._logname('.', 'bin', 'Test.case', 100))
+
+      self.assertEqual(
+        os.path.join('..', 'a', 'b', 'bin-Test_case_2-1.log'),
+        gtest_parallel.Task._logname(os.path.join('..', 'a', 'b'),
+                                    os.path.join('..', 'bin'),
+                                    'Test.case/2', 1))
+
+      self.assertEqual(
+        os.path.join('..', 'a', 'b', 'bin-Test_case_2-5.log'),
+        gtest_parallel.Task._logname(os.path.join('..', 'a', 'b'),
+                                    os.path.join(root, 'c', 'd', 'bin'),
+                                    'Test.case/2', 5))
+
+      self.assertEqual(
+        os.path.join(root, 'a', 'b', 'bin-Instantiation_Test_case_2-3.log'),
+        gtest_parallel.Task._logname(os.path.join(root, 'a', 'b'),
+                                    os.path.join('..', 'c', 'bin'),
+                                    'Instantiation/Test.case/2', 3))
+
+      self.assertEqual(
+        os.path.join(root, 'a', 'b', 'bin-Test_case-1.log'),
+        gtest_parallel.Task._logname(os.path.join(root, 'a', 'b'),
+                                    os.path.join(root, 'c', 'd', 'bin'),
+                                    'Test.case', 1))
+      MAX_PREFIX_LENGTH=240
+      long_test_name = 'a' * (os.statvfs('.').f_namemax if hasattr(os, 'statvfs') else MAX_PREFIX_LENGTH + 1)
+      truncated_log = gtest_parallel.Task._logname(os.path.join(root, 'out'),
+                                    os.path.join(root, 'bin'),
+                                    long_test_name, 1)
+      self.assertNotEqual('bin-' + long_test_name + '-1.log', os.path.basename(truncated_log))
+      self.assertTrue(truncated_log.endswith('-1.log'))
+      self.assertTrue(truncated_log.startswith(os.path.join(root, 'out', 'bin-' + long_test_name[:MAX_PREFIX_LENGTH-len('bin--1.log')])))
 
   def test_logs_to_temporary_files_without_output_dir(self):
     log_file = gtest_parallel.Task._logname(None, None, None, None)