Fix Windows cp1252 encoding error by detecting console encoding (#55)

Add encoding detection to conditionally display emoji based on console
capabilities. This fixes the UnicodeEncodeError on Windows while
preserving the emoji for UTF-8 capable consoles.

Changes:
- Add supports_unicode() function to detect if console can handle emojis
- Conditionally prefix message with 🎂 emoji only when supported
- Add comprehensive tests for different encoding scenarios

The fix works by:
1. Checking sys.stdout.encoding
2. Testing if the encoding can encode the emoji
3. Using emoji only if encoding succeeds
4. Falling back to plain text for cp1252, ASCII, latin-1, etc.

This ensures:
- UTF-8 consoles (Linux/macOS) see the emoji
- cp1252 consoles (Windows) see plain text without errors
- No logging errors appear in CI output

Related to #55

Author: jensens

src/mxdev/main.py

@@ -11,6 +11,7 @@
 
 import argparse
 import logging
+import sys
 
 
 parser = argparse.ArgumentParser(
@@ -44,6 +45,23 @@
 parser.add_argument("-v", "--verbose", help="Increase verbosity", action="store_true")
 
 
+def supports_unicode() -> bool:
+    """Check if stdout supports Unicode/emoji encoding.
+
+    Returns True if the console encoding can handle Unicode emojis,
+    False otherwise (e.g., cp1252 on Windows).
+    """
+    try:
+        encoding = sys.stdout.encoding
+        if not encoding:
+            return False
+        # Test if the encoding can handle the cake emoji
+        "🎂".encode(encoding)
+        return True
+    except (AttributeError, UnicodeEncodeError, LookupError):
+        return False
+
+
 def main() -> None:
     args = parser.parse_args()
     loglevel = logging.INFO
@@ -78,5 +96,7 @@ def main() -> None:
     write(state)
     write_hooks(state, hooks)
     out_requirements = state.configuration.out_requirements
-    logger.info(f"🎂 You are now ready for: pip install -r {out_requirements}")
+    # Use emoji only if console encoding supports it (avoid cp1252 errors on Windows)
+    prefix = "🎂 " if supports_unicode() else ""
+    logger.info(f"{prefix}You are now ready for: pip install -r {out_requirements}")
     logger.info("   (path to pip may vary dependent on your installation method)")

tests/test_main.py

@@ -1,5 +1,7 @@
+import io
 import pathlib
 import pytest
+import sys
 from unittest.mock import patch, MagicMock
 import logging
 
@@ -93,3 +95,63 @@ def test_parser_verbose():
 
     args = parser.parse_args(["-v"])
     assert args.verbose is True
+
+
+def test_supports_unicode_with_utf8():
+    """Test supports_unicode returns True for UTF-8 encoding."""
+    from mxdev.main import supports_unicode
+
+    # Mock stdout with UTF-8 encoding
+    mock_stdout = MagicMock()
+    mock_stdout.encoding = "utf-8"
+
+    with patch("sys.stdout", mock_stdout):
+        assert supports_unicode() is True
+
+
+def test_supports_unicode_with_cp1252():
+    """Test supports_unicode returns False for cp1252 encoding."""
+    from mxdev.main import supports_unicode
+
+    # Mock stdout with cp1252 encoding
+    mock_stdout = MagicMock()
+    mock_stdout.encoding = "cp1252"
+
+    with patch("sys.stdout", mock_stdout):
+        assert supports_unicode() is False
+
+
+def test_supports_unicode_with_no_encoding():
+    """Test supports_unicode returns False when encoding is None."""
+    from mxdev.main import supports_unicode
+
+    # Mock stdout with no encoding
+    mock_stdout = MagicMock()
+    mock_stdout.encoding = None
+
+    with patch("sys.stdout", mock_stdout):
+        assert supports_unicode() is False
+
+
+def test_supports_unicode_with_ascii():
+    """Test supports_unicode returns False for ASCII encoding."""
+    from mxdev.main import supports_unicode
+
+    # Mock stdout with ASCII encoding
+    mock_stdout = MagicMock()
+    mock_stdout.encoding = "ascii"
+
+    with patch("sys.stdout", mock_stdout):
+        assert supports_unicode() is False
+
+
+def test_supports_unicode_with_latin1():
+    """Test supports_unicode returns False for latin-1 encoding."""
+    from mxdev.main import supports_unicode
+
+    # Mock stdout with latin-1 encoding
+    mock_stdout = MagicMock()
+    mock_stdout.encoding = "latin-1"
+
+    with patch("sys.stdout", mock_stdout):
+        assert supports_unicode() is False