on Windows try the API before enabling conversion

colorama/ansitowin32.py

@@ -5,7 +5,7 @@
 
 from .ansi import AnsiFore, AnsiBack, AnsiStyle, Style
 from .winterm import WinTerm, WinColor, WinStyle
-from .win32 import windll
+from .win32 import windll, winapi_test
 
 
 winterm = None
@@ -56,16 +56,20 @@ def __init__(self, wrapped, convert=None, strip=None, autoreset=False):
         self.stream = StreamWrapper(wrapped, self)
 
         on_windows = os.name == 'nt'
-        on_emulated_windows = on_windows and 'TERM' in os.environ
+        # We test if the WinAPI works, because even if we are on Windows
+        # we may be using a terminal that doesn't support the WinAPI
+        # (e.g. Cygwin Terminal). In this case it's up to the terminal
+        # to support the ANSI codes.
+        conversion_supported = on_windows and winapi_test()
 
         # should we strip ANSI sequences from our output?
         if strip is None:
-            strip = on_windows and not on_emulated_windows
+            strip = conversion_supported
         self.strip = strip
 
         # should we should convert ANSI sequences into win32 calls?
         if convert is None:
-            convert = on_windows and not wrapped.closed and not on_emulated_windows and is_a_tty(wrapped)
+            convert = conversion_supported and not wrapped.closed and is_a_tty(wrapped)
         self.convert = convert
 
         # dict of ansi codes to win32 functions and parameters

colorama/tests/ansitowin32_test.py

@@ -47,7 +47,7 @@ def testInit(self):
         self.assertEqual(stream.autoreset, auto)
 
     @patch('colorama.ansitowin32.winterm', None)
-    @patch('os.environ', dict())
+    @patch('colorama.ansitowin32.winapi_test', lambda *_: True)
     def testStripIsTrueOnWindows(self):
         with osname('nt'):
             mockStdout = Mock()

colorama/tests/initialise_test.py

@@ -40,17 +40,16 @@ def assertNotWrapped(self):
         self.assertIs(sys.stderr, orig_stderr, 'stderr should not be wrapped')
 
     @patch('colorama.initialise.reset_all')
-    @patch('os.environ', dict())
+    @patch('colorama.ansitowin32.winapi_test', lambda *_: True)
     def testInitWrapsOnWindows(self, _):
         with osname("nt"):
             init()
             self.assertWrapped()
 
     @patch('colorama.initialise.reset_all')
-    @patch('os.environ', dict(TERM=''))
+    @patch('colorama.ansitowin32.winapi_test', lambda *_: False)
     def testInitDoesntWrapOnEmulatedWindows(self, _):
         with osname("nt"):
-            os.environ['TERM']
             init()
             self.assertNotWrapped()
 
@@ -87,7 +86,7 @@ def testInitWrapOffIncompatibleWithAutoresetOn(self):
         self.assertRaises(ValueError, lambda: init(autoreset=True, wrap=False))
 
     @patch('colorama.ansitowin32.winterm', None)
-    @patch('os.environ', dict())
+    @patch('colorama.ansitowin32.winapi_test', lambda *_: True)
     def testInitOnlyWrapsOnce(self):
         with osname("nt"):
             init()

colorama/win32.py

@@ -12,6 +12,7 @@
 except (AttributeError, ImportError):
     windll = None
     SetConsoleTextAttribute = lambda *_: None
+    winapi_test = lambda *_: None
 else:
     from ctypes import byref, Structure, c_char, POINTER
 
@@ -93,6 +94,13 @@ def __str__(self):
         STDERR: _GetStdHandle(STDERR),
     }
 
+    def winapi_test():
+        handle = handles[STDOUT]
+        csbi = CONSOLE_SCREEN_BUFFER_INFO()
+        success = _GetConsoleScreenBufferInfo(
+            handle, byref(csbi))
+        return bool(success)
+
     def GetConsoleScreenBufferInfo(stream_id=STDOUT):
         handle = handles[stream_id]
         csbi = CONSOLE_SCREEN_BUFFER_INFO()