Bug 1638954 - Run 'mach cppunittest' with python 3; r=bc

Differential Revision: https://phabricator.services.mozilla.com/D77258

mach

@@ -16,7 +16,6 @@ py2commands="
     browsertime
     check-spidermonkey
     clang-format
-    cppunittest
     cramtest
     devtools-css-db
     firefox-ui-functional

testing/remotecppunittests.py

@@ -86,7 +86,7 @@ class RemoteCPPUnitTests(cppunittests.CPPUnitTests):
                     for root, dirs, paths in os.walk(local_arm_lib):
                         for path in paths:
                             if path.endswith(".so"):
-                                print("Pushing %s..".format(path), file=sys.stderr)
+                                print("Pushing {}..".format(path), file=sys.stderr)
                                 remote_file = posixpath.join(
                                     self.remote_bin_dir, path)
                                 local_file = os.path.join(root, path)

testing/runcppunittests.py

@@ -51,13 +51,15 @@ class CPPUnitTests(object):
                 proc = mozprocess.ProcessHandler([prog],
                                                  cwd=tempdir,
                                                  env=env,
-                                                 storeOutput=False)
+                                                 storeOutput=False,
+                                                 universal_newlines=True)
             else:
                 proc = mozprocess.ProcessHandler([prog],
                                                  cwd=tempdir,
                                                  env=env,
                                                  storeOutput=True,
-                                                 processOutputLine=lambda _: None)
+                                                 processOutputLine=lambda _: None,
+                                                 universal_newlines=True)
             # TODO: After bug 811320 is fixed, don't let .run() kill the process,
             # instead use a timeout in .wait() and then kill to get a stack.
             test_timeout = CPPUnitTests.TEST_PROC_TIMEOUT * timeout_factor