Added strip_ansi() function and visible_prompt propery

Transcript testing now strips ANSI escape codes from the current line and current prompt before comparing the start of the current line with the current prompt to see if it is a command.

This makes it easier to use transcript testing with applications that colorize the prompt.

Author: tleonhardt

cmd2.py

@@ -389,6 +389,19 @@ class EmptyStatement(Exception):
     pass
 
 
+# Regular expression to match ANSI escape codes
+ANSI_ESCAPE_RE = re.compile(r'\x1b[^m]*m')
+
+
+def strip_ansi(text):
+    """Strip ANSI escape codes from a string.
+
+    :param text: str - a string which may contain ANSI escape codes
+    :return: str - the same string with any ANSI escape codes removed
+    """
+    return ANSI_ESCAPE_RE.sub('', text)
+
+
 class Cmd(cmd.Cmd):
     """An easy but powerful framework for writing line-oriented command interpreters.
 
@@ -520,6 +533,17 @@ def __init__(self, completekey='tab', stdin=None, stdout=None, use_ipython=False
 
     # -----  Methods related to presenting output to the user -----
 
+    @property
+    def visible_prompt(self):
+        """Read-only property to get the visible prompt with any ANSI escape codes stripped.
+
+        Used by transcript testing to make it easier and more reliable when users are doing things like coloring the
+        prompt using ANSI color codes.
+
+        :return: str - prompt stripped of any ANSI escape codes
+        """
+        return strip_ansi(self.prompt)
+
     def _finalize_app_parameters(self):
         self.commentGrammars.ignore(pyparsing.quotedString).setParseAction(lambda x: '')
         # noinspection PyUnresolvedReferences
@@ -2183,18 +2207,18 @@ def runTest(self):  # was testall
     def _test_transcript(self, fname, transcript):
         line_num = 0
         finished = False
-        line = next(transcript)
+        line = strip_ansi(next(transcript))
         line_num += 1
         while not finished:
             # Scroll forward to where actual commands begin
-            while not line.startswith(self.cmdapp.prompt):
+            while not line.startswith(self.cmdapp.visible_prompt):
                 try:
-                    line = next(transcript)
+                    line = strip_ansi(next(transcript))
                 except StopIteration:
                     finished = True
                     break
                 line_num += 1
-            command = [line[len(self.cmdapp.prompt):]]
+            command = [line[len(self.cmdapp.visible_prompt):]]
             line = next(transcript)
             # Read the entirety of a multi-line command
             while line.startswith(self.cmdapp.continuation_prompt):
@@ -2213,13 +2237,13 @@ def _test_transcript(self, fname, transcript):
             self.cmdapp.onecmd_plus_hooks(command)
             result = self.cmdapp.stdout.read()
             # Read the expected result from transcript
-            if line.startswith(self.cmdapp.prompt):
+            if strip_ansi(line).startswith(self.cmdapp.visible_prompt):
                 message = '\nFile %s, line %d\nCommand was:\n%r\nExpected: (nothing)\nGot:\n%r\n' % \
                           (fname, line_num, command, result)
                 self.assert_(not (result.strip()), message)
                 continue
             expected = []
-            while not line.startswith(self.cmdapp.prompt):
+            while not strip_ansi(line).startswith(self.cmdapp.visible_prompt):
                 expected.append(line)
                 try:
                     line = next(transcript)