Fixed error message omission during Lab execution

CHANGELOG.md

@@ -8,6 +8,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 - Fixed readthedocs.org documentation build now requiring a .readthedocs.yaml config file
+- Fixed a bug where the actual error message from an exception happening during execution through a `Lab` instance would
+be omitted
 
 
 ## [0.3.0] - 2024-04-23

alkymi/lab.py

@@ -151,7 +151,9 @@ def _add_user_args_(self, parser: argparse.ArgumentParser, args: Dict[str, Arg])
     @staticmethod
     def _remove_alkymi_internals_from_traceback(e: Exception, num_stack_frames_to_omit: int) -> str:
         """
-
+        Remove parts of the stack trace internal to alkymi to create a shorter and less noisy error message. Will
+        prepend the current call stack to accurately present the whole exception as though it had bubbled all the way
+        up to the caller
 
         :param e: The exception to load the traceback from
         :param num_stack_frames_to_omit: A number of stack frames to omit - can be used to e.g. ignore this call on the
@@ -182,7 +184,8 @@ def _remove_alkymi_internals_from_traceback(e: Exception, num_stack_frames_to_om
         # Finally, combine the stack with an "omitted" statement and the filtered traceback
         return "".join(stack.format()) + \
             "    <alkymi internals omitted...>\n" + \
-            "".join(traceback.StackSummary.from_list(filtered_frames).format())
+            "".join(traceback.StackSummary.from_list(filtered_frames).format()) + \
+            "".join(traceback.format_exception_only(type(e), value=e))
 
     def __repr__(self) -> str:
         """

tests/test_lab.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python
 import io
+import time
 from typing import List
 
 import pytest
@@ -187,9 +188,11 @@ def test_lab_omits_alkymi_internals_in_traceback(capsys: pytest.CaptureFixture)
     """
 
     # Create a lab containing a single recipe that will raise on execution
+    expected_error_message = f"Failure @ {time.time()}"
+
     @alk.recipe()
     def fail() -> None:
-        raise RuntimeError("Failure")
+        raise RuntimeError(expected_error_message)
 
     lab = alk.Lab("failure lab")
     lab.add_recipe(fail)
@@ -206,7 +209,8 @@ def fail() -> None:
     assert 'lab.brew(fail)' in printed_error  # The lab invocation that led to the failure
     assert '<alkymi internals omitted...>' in printed_error  # A statement that alkymi internals were omitted
     assert 'in fail' in printed_error  # The recipe (function) that failed
-    assert 'raise RuntimeError("Failure")' in printed_error  # The line that failed
+    assert 'RuntimeError(expected_error_message)' in printed_error  # The line that failed
+    assert f"RuntimeError: {expected_error_message}" in printed_error  # The actual error message
 
     # The traceback should not contain the following:
     assert 'alkymi/core.py' not in printed_error  # Any line related to the internal execution engine of alkymi