safer terminal I/O detection

src/mog_commons/__init__.py

@@ -1 +1 @@
-__version__ = '0.1.20'
+__version__ = '0.1.21'

src/mog_commons/terminal.py

@@ -63,7 +63,7 @@ def __init__(self, term_type=None, encoding=None,
 
     @staticmethod
     def _can_getch_enable(stdin):
-        if stdin.isatty():
+        if hasattr(stdin, 'isatty') and stdin.isatty():
             return os.name == 'nt' or hasattr(stdin, 'fileno')
         return False
 
@@ -125,7 +125,7 @@ def clear(self):
         """
         Clear the terminal screen.
         """
-        if self.stdout.isatty() or self.term_type == 'mintty':
+        if hasattr(self.stdout, 'isatty') and self.stdout.isatty() or self.term_type == 'mintty':
             cmd, shell = {
                 'posix': ('clear', False),
                 'nt': ('cls', True),
@@ -138,7 +138,7 @@ def clear_input_buffer(self):
         """
         Clear the input buffer.
         """
-        if self.stdin.isatty():
+        if hasattr(self.stdin, 'isatty') and self.stdin.isatty():
             if os.name == 'nt':
                 while msvcrt.kbhit():
                     msvcrt.getch()

tests/mog_commons/test_terminal.py

@@ -9,6 +9,11 @@
 
 
 class TestTerminal(TestCase):
+    def test_clear(self):
+        with self.withAssertOutput('', '') as (out, err):
+            # assume this should not raise an error
+            TerminalHandler(stdout=out, stderr=err).clear()
+
     def test_getch_from_file(self):
         with open(os.path.join('tests', 'resources', 'test_terminal_input.txt')) as f:
             t = TerminalHandler(stdin=f)