Wrap up set_output_directory as a function and include tests functions

Author: yucongalicechen

src/diffpy/labpdfproc/labpdfprocapp.py

@@ -3,6 +3,7 @@
 from pathlib import Path
 
 from diffpy.labpdfproc.functions import apply_corr, compute_cve
+from diffpy.labpdfproc.tools import set_output_directory
 from diffpy.utils.parsers.loaddata import loadData
 from diffpy.utils.scattering_objects.diffraction_objects import XQUANTITIES, Diffraction_object
 
@@ -65,13 +66,11 @@ def main():
     args = get_args()
     wavelength = WAVELENGTHS[args.anode_type]
     filepath = Path(args.input_file)
-    output_dir = Path(args.output_directory).resolve() if args.output_directory else Path.cwd()
-    output_dir.mkdir(parents=True, exist_ok=True)
-    args.output_directory = output_dir
+    args.output_directory = set_output_directory(args)
     outfilestem = filepath.stem + "_corrected"
     corrfilestem = filepath.stem + "_cve"
-    outfile = output_dir / (outfilestem + ".chi")
-    corrfile = output_dir / (corrfilestem + ".chi")
+    outfile = args.output_directory / (outfilestem + ".chi")
+    corrfile = args.output_directory / (corrfilestem + ".chi")
 
     if outfile.exists() and not args.force_overwrite:
         sys.exit(

src/diffpy/labpdfproc/tests/test_tools.py

@@ -0,0 +1,19 @@
+import argparse
+from pathlib import Path
+
+import pytest
+
+from diffpy.labpdfproc.tools import set_output_directory
+
+params1 = [
+    ([None], [Path.cwd()]),
+    (["corrected"], [Path("corrected").resolve()]),
+]
+
+
+@pytest.mark.parametrize("inputs, expected", params1)
+def test_set_output_directory(inputs, expected):
+    expected_output_directory = expected[0]
+    actual_args = argparse.Namespace(output_directory=inputs[0])
+    actual_output_directory = set_output_directory(actual_args)
+    assert actual_output_directory == expected_output_directory

src/diffpy/labpdfproc/tools.py

@@ -0,0 +1,7 @@
+from pathlib import Path
+
+
+def set_output_directory(args):
+    output_dir = Path(args.output_directory).resolve() if args.output_directory else Path.cwd()
+    output_dir.mkdir(parents=True, exist_ok=True)
+    return output_dir