pySim.log: apply cmd2 colors through _style()

The color scheme takes either
- a raw escape sequence like "\033[33m" (pySim-read,
pySim-prog, contrib/csv-to-pgsql.py)
- a cmd2 color object (pySim-shell)

Color of cmd2 >= 3.0.0 is a StrEnum, which led to
pySim-shell warnings like

  yellowWARNING: EF.DIR seems to be empty!

with a stray reset at the end.

Fixed by exclusing Enum from the raw sequence branch.

Change-Id: I8bae9fc3c54f1dab481d743d3b68e32e9d09267a

pySim/log.py

@@ -24,6 +24,7 @@
 #
 
 import logging
+import enum
 import cmd2
 from packaging import version
 
@@ -126,7 +127,7 @@ class PySimLogger:
                 formatted_message = logging.Formatter.format(PySimLogger.__formatter, record)
             color = PySimLogger.colors.get(record.levelno)
             if color:
-                if isinstance(color, str):
+                if isinstance(color, str) and not isinstance(color, enum.Enum):
                     PySimLogger.print_callback(color + formatted_message + "\033[0m")
                 else:
                     PySimLogger.print_callback(_style(formatted_message, fg = color))

tests/unittests/test_log.py

@@ -20,11 +20,20 @@
 
 import unittest
 import logging
+import cmd2
+from packaging import version
 from pySim.log import PySimLogger
 import io
 import sys
 from inspect import currentframe, getframeinfo
 
+if version.parse(cmd2.__version__) >= version.parse("3.0.0"):
+    from cmd2 import Color # pylint: disable=no-name-in-module
+    YELLOW = Color.YELLOW
+else: # cmd2>=2.6.2
+    from cmd2 import Fg # pylint: disable=no-name-in-module
+    YELLOW = Fg.YELLOW
+
 log = PySimLogger.get(__name__)
 
 TEST_MSG_DEBUG = "this is a debug message"
@@ -128,5 +137,18 @@ class PySimLogger_Test(unittest.TestCase):
         expected_message = "CRITICAL: " + TEST_MSG_CRITICAL
         log.critical(TEST_MSG_CRITICAL)
 
+    def test_05_color(self):
+        # A color is either
+        # - raw escape sequence
+        # - cmd2 color object
+        global expected_message
+        expected_message = "\033[33mWARNING: " + TEST_MSG_WARNING + "\033[0m"
+
+        PySimLogger.setup(self._test_print_callback, {logging.WARN: "\033[33m"})
+        log.warning(TEST_MSG_WARNING)
+
+        PySimLogger.setup(self._test_print_callback, {logging.WARN: YELLOW})
+        log.warning(TEST_MSG_WARNING)                   # don't leak cmd2 Color StrEnum
+
 if __name__ == '__main__':
     unittest.main()