behavior: if no wavelength is specified, ValueError is raised instead of print statement

Author: cadenmyers13

src/diffpy/labpdfproc/tools.py

@@ -224,12 +224,28 @@ def load_wavelength_from_config_file(args):
     args : argparse.Namespace
         The updated arguments with the updated wavelength and anode type.
     """
-    global_config = _load_config(Path().home() / "diffpyconfig.json")
-    local_config = _load_config(Path().cwd() / "diffpyconfig.json")
-    local_has_data = local_config and "wavelength" in local_config
-    global_has_data = global_config and "wavelength" in global_config
-    if not local_has_data and not global_has_data:
-        print(
+
+    if args.wavelength is not None:
+        return normalize_wavelength(args)
+
+    global_config_file = _load_config(Path().home() / "diffpyconfig.json")
+    local_config_file = _load_config(Path().cwd() / "diffpyconfig.json")
+    config_file = None
+    if (
+        isinstance(local_config_file, dict)
+        and "wavelength" in local_config_file
+    ):
+        config_file = local_config_file
+    elif (
+        isinstance(global_config_file, dict)
+        and "wavelength" in global_config_file
+    ):
+        config_file = global_config_file
+    if config_file is not None:
+        args.wavelength = config_file.get("wavelength")
+        return normalize_wavelength(args)
+    else:
+        raise ValueError(
             "No configuration file was found containing information "
             "about the wavelength or anode type. \n"
             "You can add the wavelength or anode type "
@@ -240,13 +256,6 @@ def load_wavelength_from_config_file(args):
             "For more information, please refer to www.diffpy.org/"
             "diffpy.labpdfproc/examples/toolsexample.html"
         )
-    if args.wavelength is not None:
-        return normalize_wavelength(args)
-    config = local_config if local_has_data else global_config
-    if config:
-        args.wavelength = config.get("wavelength")
-        return normalize_wavelength(args)
-    return args
 
 
 def set_wavelength(args):

tests/test_tools.py

@@ -311,15 +311,76 @@ def test_load_wavelength_from_config_file_with_local_conf_file(
     assert actual_args.wavelength == expected["wavelength"]
 
 
+@pytest.mark.parametrize(
+    "local_config, home_config",
+    [
+        # C1: no config files exist
+        # expected: raise ValueError
+        (None, None),
+        # C2: local config is empty, no home config
+        # expected: raise ValueError
+        ({}, None),
+        # C3: no local config, home config is empty
+        # expected: raise ValueError
+        (None, {}),
+        # C4: both config files are empty
+        # expected: raise ValueError
+        ({}, {}),
+    ],
+)
+def test_load_wavelength_from_config_file_without_conf_files_bad(
+    mocker,
+    user_filesystem,
+    local_config,
+    home_config,
+):
+    # User tries to correct data without specifying wavelength and
+    # no config files
+    # with wavelength exist -- expected to raise ValueError
+    cwd = Path(user_filesystem)
+    home_dir = cwd / "home_dir"
+    mocker.patch("pathlib.Path.home", return_value=home_dir)
+    os.chdir(cwd)
+
+    local_config_file = cwd / "diffpyconfig.json"
+    if local_config_file.exists():
+        local_config_file.unlink()
+    home_config_file = home_dir / "diffpyconfig.json"
+    if home_config_file.exists():
+        home_config_file.unlink()
+
+    if local_config is not None:
+        with open(local_config_file, "w") as f:
+            json.dump(local_config, f)
+    if home_config is not None:
+        with open(home_config_file, "w") as f:
+            json.dump(home_config, f)
+
+    cli_inputs = ["mud", "data.xy", "2.5"]
+    actual_args = get_args_cli(cli_inputs)
+
+    msg = re.escape(
+        "No configuration file was found containing information "
+        "about the wavelength or anode type. \n"
+        "You can add the wavelength or anode type "
+        "to a configuration file on the current computer "
+        "and it will be automatically associated with "
+        "subsequent diffpy data by default. \n"
+        "You will only have to do that once. \n"
+        "For more information, please refer to www.diffpy.org/"
+        "diffpy.labpdfproc/examples/toolsexample.html"
+    )
+    with pytest.raises(ValueError, match=msg):
+        load_wavelength_from_config_file(actual_args)
+
+
 @pytest.mark.parametrize(
     "inputs, expected",
     [
         # Test when no config files exist,
         # expect to return args without modification.
         # This test only checks loading behavior,
         # not value validation (which is handled by `set_wavelength`).
-        # C1: no args
-        ([], {"wavelength": None}),
         # C1: wavelength provided
         (["--wavelength", "0.25"], {"wavelength": 0.25}),
         # C2: anode type provided