Clean up warning capture

src/calliope/exceptions.py

@@ -9,20 +9,6 @@
 import warnings
 from typing import Optional, Union
 
-# Enable simple format when printing ModelWarnings
-formatwarning_orig = warnings.showwarning
-
-
-def _formatwarning(message, category, filename, lineno, file=None, line=None):
-    """Formats ModelWarnings as "Warning: message" without extra crud"""
-    if category == ModelWarning:
-        return "Warning: " + str(message) + "\n"
-    else:
-        return formatwarning_orig(message, category, filename, lineno, file, line)
-
-
-warnings.showwarning = _formatwarning
-
 
 class ModelError(Exception):
     """
@@ -52,8 +38,19 @@ class BackendWarning(Warning):
     pass
 
 
+def _formatwarning(message, category, *args, **kwargs):
+    """Formats ModelWarnings as "ModelWarning: message" without extra crud"""
+
+    if category in [ModelWarning, BackendWarning]:
+        return f"{category.__name__}: {message}\n"
+    else:
+        return warnings._formatwarning_orig(message, category, *args, **kwargs)
+
+
 def warn(message, _class=ModelWarning):
+    warnings.formatwarning = _formatwarning
     warnings.warn(message, _class)
+    warnings.formatwarning = warnings._formatwarning_orig
 
 
 def print_warnings_and_raise_errors(

src/calliope/util/logging.py

@@ -12,6 +12,8 @@
 
 _time_format = "%Y-%m-%d %H:%M:%S"
 
+_orig_py_warning_handlers = logging.getLogger("py.warnings").handlers
+
 
 def setup_root_logger(
     verbosity: str | int, capture_warnings: bool = True
@@ -49,12 +51,15 @@ def setup_root_logger(
     root_logger.addHandler(console)
     root_logger.setLevel(verbosity)
 
+    py_warnings_logger = logging.getLogger("py.warnings")
     if capture_warnings:
         logging.captureWarnings(True)
-        logging.getLogger("py.warnings").setLevel(verbosity)
+        py_warnings_logger.handlers = _orig_py_warning_handlers + [console]
+        py_warnings_logger.setLevel(verbosity)
     else:
         logging.captureWarnings(False)
         logging.getLogger("py.warnings").setLevel("WARNING")
+        py_warnings_logger.handlers = _orig_py_warning_handlers
 
     return root_logger
 

tests/test_core_util.py

@@ -69,11 +69,19 @@ def test_timing_log(self):
             time_since_solve_start=True,
         )
 
-    @pytest.mark.parametrize(["capture", "expected_level"], [(True, 20), (False, 30)])
-    def test_capture_warnings(self, capture, expected_level):
+    @pytest.mark.parametrize(
+        ["capture", "expected_level", "n_handlers"], [(True, 20, 1), (False, 30, 0)]
+    )
+    def test_capture_warnings(self, capture, expected_level, n_handlers):
         calliope.set_log_verbosity("info", capture_warnings=capture)
 
         assert logging.getLogger("py.warnings").getEffectiveLevel() == expected_level
+        assert len(logging.getLogger("py.warnings").handlers) == n_handlers
+
+    def test_capture_warnings_handlers_dont_append(self):
+        for level in ["critical", "warning", "info", "debug"]:
+            calliope.set_log_verbosity(level, capture_warnings=True)
+            assert len(logging.getLogger("py.warnings").handlers) == 1
 
 
 class TestGenerateRuns: