gclient_utils: Fix bug in CheckCallAndFilter in Python 3.

Header was printed using sys.stdout, but the rest of the output was
printed using sys.stdout.buffer, causing the output to be written
before the header.

Bug: 984182
Change-Id: If6aaa05a579c3b0c73ce8ffe48f3a4e777fa16fa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1790254
Auto-Submit: Edward Lesmes <ehmaldonado@chromium.org>
Commit-Queue: Andrii Shyshkalov <tandrii@google.com>
Reviewed-by: Andrii Shyshkalov <tandrii@google.com>

gclient_utils.py

@@ -527,7 +527,8 @@ def CheckCallAndFilter(args, print_stdout=False, filter_fn=None,
     header += '\n'
 
     if print_stdout:
-      sys.stdout.write(header)
+      stdout_write = getattr(sys.stdout, 'buffer', sys.stdout).write
+      stdout_write(header.encode())
     if filter_fn:
       filter_fn(header)
 

tests/gclient_utils_test.py

@@ -4,6 +4,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+from __future__ import print_function
 from __future__ import unicode_literals
 
 import io
@@ -33,7 +34,15 @@ class CheckCallAndFilterTestCase(unittest.TestCase):
 
   def setUp(self):
     super(CheckCallAndFilterTestCase, self).setUp()
-    mock.patch('sys.stdout', io.StringIO()).start()
+    self.printfn = io.StringIO()
+    self.stdout = io.BytesIO()
+    if sys.version_info.major == 2:
+      mock.patch('sys.stdout', self.stdout).start()
+      mock.patch('__builtin__.print', self.printfn.write).start()
+    else:
+      mock.patch('sys.stdout', mock.Mock()).start()
+      mock.patch('sys.stdout.buffer', self.stdout).start()
+      mock.patch('builtins.print', self.printfn.write).start()
     mock.patch('sys.stdout.flush', lambda: None).start()
     self.addCleanup(mock.patch.stopall)
 
@@ -58,6 +67,7 @@ class CheckCallAndFilterTestCase(unittest.TestCase):
         'allo',
         'addb',
         '✔'])
+    self.assertEqual(self.stdout.getvalue(), b'')
 
     mockPopen.assert_called_with(
         args, cwd=cwd, stdout=subprocess2.PIPE, stderr=subprocess2.STDOUT,
@@ -110,10 +120,35 @@ class CheckCallAndFilterTestCase(unittest.TestCase):
                 stderr=subprocess2.STDOUT, bufsize=0),
         ])
 
+    self.assertEqual(self.stdout.getvalue(), b'')
     self.assertEqual(
-        sys.stdout.getvalue(),
+        self.printfn.getvalue(),
         'WARNING: subprocess \'"boo" "foo" "bar"\' in bleh failed; will retry '
-        'after a short nap...\n')
+        'after a short nap...')
+
+  @mock.patch('subprocess2.Popen')
+  def testCHeckCallAndFilter_PrintStdout(self, mockPopen):
+    cwd = 'bleh'
+    args = ['boo', 'foo', 'bar']
+    test_string = 'ahah\naccb\nallo\naddb\n✔'
+
+    mockPopen.return_value = self.ProcessIdMock(test_string)
+
+    result = gclient_utils.CheckCallAndFilter(
+        args, cwd=cwd, show_header=True, always_show_header=True,
+        print_stdout=True)
+
+    self.assertEqual(result, test_string.encode('utf-8'))
+    self.assertEqual(
+        self.stdout.getvalue().splitlines(),
+        [
+            b'________ running \'boo foo bar\' in \'bleh\'',
+            b'ahah',
+            b'accb',
+            b'allo',
+            b'addb',
+            b'\xe2\x9c\x94',
+        ])
 
 
 class SplitUrlRevisionTestCase(unittest.TestCase):