--- a/python/mach_commands.py
+++ b/python/mach_commands.py
@@ -110,18 +110,21 @@ class MachCommands(MachCommandBase):
                 test_objects = resolver.resolve_tests(flavor='python')
 
         for test in test_objects:
             found_tests = True
             f = test['path']
             file_displayed_test = []  # Used as a boolean.
 
             def _line_handler(line):
-                if not file_displayed_test and line.startswith('TEST-'):
-                    file_displayed_test.append(True)
+                if not file_displayed_test:
+                    output = ('Ran' in line or 'collected' in line or
+                              line.startswith('TEST-'))
+                    if output:
+                        file_displayed_test.append(True)
 
             inner_return_code = self.run_process(
                 [self.virtualenv_manager.python_path, f],
                 ensure_exit_code=False,  # Don't throw on non-zero exit code.
                 log_name='python-test',
                 # subprocess requires native strings in os.environ on Windows
                 append_env={b'PYTHONDONTWRITEBYTECODE': str('1')},
                 line_handler=_line_handler)