strengthen the ValueError message

Author: cadenmyers13

src/diffpy/labpdfproc/tools.py

@@ -246,15 +246,20 @@ def load_wavelength_from_config_file(args):
         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 "
-            "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"
+            "\nThe wavelength was not specified and no "
+            "configuration file 'diffpyconfig.json' containing "
+            "the wavelength or X-ray source was found in either the "
+            "local or home directories. Either specify the wavelength "
+            "or source using the -w/--wavelength option or "
+            "create a configuration file.\n\n"
+            "You can add the wavelength or anode type to a "
+            "configuration file on this computer. Once created, it "
+            "will be automatically used for subsequent diffpy data "
+            "by default, and you will only need to do this once.\n\n"
+            "For detailed instructions on creating the configuration "
+            "file, please refer to:\n"
+            "https://www.diffpy.org/diffpy.labpdfproc/examples/"
+            "toolsexample.html"
         )
 
 

tests/test_tools.py

@@ -360,15 +360,20 @@ def test_load_wavelength_from_config_file_without_conf_files_bad(
     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"
+        "\nThe wavelength was not specified and no "
+        "configuration file 'diffpyconfig.json' containing "
+        "the wavelength or X-ray source was found in either the "
+        "local or home directories. Either specify the wavelength "
+        "or source using the -w/--wavelength option or "
+        "create a configuration file.\n\n"
+        "You can add the wavelength or anode type to a "
+        "configuration file on this computer. Once created, it "
+        "will be automatically used for subsequent diffpy data "
+        "by default, and you will only need to do this once.\n\n"
+        "For detailed instructions on creating the configuration "
+        "file, please refer to:\n"
+        "https://www.diffpy.org/diffpy.labpdfproc/examples/"
+        "toolsexample.html"
     )
     with pytest.raises(ValueError, match=msg):
         load_wavelength_from_config_file(actual_args)