add graceful error handling with return of status codes, closes #12

cli.py

@@ -12,7 +12,7 @@ class CliArgs:
     calib_value_y: float
 
 
-def main() -> None:
+def main() -> int:
     parser = argparse.ArgumentParser(
         description=("simple CLI tool to analyse single sensor images for anomalies")
     )
@@ -33,7 +33,7 @@ def main() -> None:
     )
     args = cast(CliArgs, parser.parse_args())
 
-    _interface.sensor_anomalies_detection(
+    return _interface.sensor_anomalies_detection(
         args.img_path,
         args.calib_value_x,
         args.calib_value_y,

src/dopt_sensor_anomalies/_interface.py

@@ -1,16 +1,44 @@
 """main pipeline interface for external calls"""
 
+from __future__ import annotations
+
+import sys
+from typing import TYPE_CHECKING, TextIO
+
 from dopt_sensor_anomalies import detection
 
+if TYPE_CHECKING:
+    from dopt_basics.result_pattern import Status
+
+
+def _print_error_state(
+    state: Status,
+    out_stream: TextIO,
+) -> None:
+    if state.ExceptionType is None:
+        raise RuntimeError("Tried to treat state as error, but no exception is registered")
+
+    msg = (
+        f"During the procedure the following exception occurred:"
+        f"\nType: {state.ExceptionType.__name__}\nDescription: {state.description}\n"
+        f"Message: {state.message}"
+    )
+    print(msg, flush=True, file=out_stream)
+
 
 def sensor_anomalies_detection(
     user_img_path: str,
     pixels_per_metric_X: float,
     pixels_per_metric_Y: float,
-) -> None:
+) -> int:
     res = detection.pipeline(
         user_img_path=user_img_path,
         pixels_per_metric_X=pixels_per_metric_X,
         pixels_per_metric_Y=pixels_per_metric_Y,
     )
+    if res.status.code != 0:
+        _print_error_state(res.status, out_stream=sys.stderr)
+        return 1
+
     res.unwrap()
+    return 0

tests/test_interface.py

@@ -1,23 +1,61 @@
 import shutil
+from io import StringIO
 from unittest.mock import patch
 
 import pytest
+from dopt_basics.result_pattern import wrap_result
 
-from dopt_sensor_anomalies import _interface, constants, errors
+from dopt_sensor_anomalies import _interface, constants
+
+
+def test_print_error_state_WrongState():
+    from dopt_basics.result_pattern import STATUS_HANDLER
+
+    MSG = "to treat state as error"
+    with pytest.raises(RuntimeError, match=MSG):
+        _interface._print_error_state(STATUS_HANDLER.SUCCESS, out_stream=StringIO())
+
+
+def test_print_error_state(tmp_path):
+    @wrap_result(100)
+    def error_func() -> None:
+        # do something
+        raise RuntimeError("Oops, error occurred")
+
+    err_state = error_func().status
+    output_file = tmp_path / "t_output.txt"
+    output_file.touch()
+
+    with open(output_file, "w") as stream:
+        _interface._print_error_state(err_state, stream)
+
+    lines: list[str]
+    with open(output_file, "r") as file:
+        lines = file.readlines()
+
+    assert "following exception" in lines[0]
+    assert "Type: RuntimeError" in lines[1]
+    assert "Description:" in lines[2]
+    assert "Message: Oops, error occurred" in lines[3]
 
 
 @patch("dopt_sensor_anomalies._find_paths.STOP_FOLDER_NAME", "lib")
 def test_sensor_anomalies_detection_FailImagePath(setup_temp_dir):
     img_path = str(setup_temp_dir / "not-existing.bmp")
+
     pixels_per_metric_X: float = 0.251
     pixels_per_metric_Y: float = 0.251
 
     MESSAGE = "The provided path seems not to exist"
 
-    with pytest.raises(FileNotFoundError, match=MESSAGE):
-        _interface.sensor_anomalies_detection(
+    with patch("sys.stderr", new_callable=StringIO) as mock_err:
+        ret = _interface.sensor_anomalies_detection(
             img_path, pixels_per_metric_X, pixels_per_metric_Y
         )
+        captured = mock_err.getvalue()
+        assert ret != 0
+        assert "FileNotFoundError" in captured
+        assert MESSAGE in captured
 
 
 @patch("dopt_sensor_anomalies._find_paths.STOP_FOLDER_NAME", "lib")
@@ -28,10 +66,14 @@ def test_sensor_anomalies_detection_FailElectrodeCount(path_img_with_failure_Ele
 
     MESSAGE = "Number of counted electrodes does not match the"
 
-    with pytest.raises(errors.InvalidElectrodeCount, match=MESSAGE):
-        _interface.sensor_anomalies_detection(
+    with patch("sys.stderr", new_callable=StringIO) as mock_err:
+        ret = _interface.sensor_anomalies_detection(
             img_path, pixels_per_metric_X, pixels_per_metric_Y
         )
+        captured = mock_err.getvalue()
+        assert ret != 0
+        assert "InvalidElectrodeCount" in captured
+        assert MESSAGE in captured
 
 
 @patch("dopt_sensor_anomalies._find_paths.STOP_FOLDER_NAME", "lib")
@@ -52,8 +94,11 @@ def test_sensor_anomalies_detection_Success(
     pixels_per_metric_X: float = 0.251
     pixels_per_metric_Y: float = 0.251
 
-    _interface.sensor_anomalies_detection(img_path, pixels_per_metric_X, pixels_per_metric_Y)
+    ret = _interface.sensor_anomalies_detection(
+        img_path, pixels_per_metric_X, pixels_per_metric_Y
+    )
 
+    assert ret == 0
     assert csv_file.exists()
     assert heatmap_file.exists()
     target_folder = results_folder / "csharp_interface"