docs: improves docstring and test comments

Author: yucongalicechen

Diff for: src/diffpy/labpdfproc/labpdfprocapp.py

@@ -56,7 +56,7 @@ def define_arguments():
             "name": ["-w", "--wavelength"],
             "help": (
                 "X-ray source wavelength in angstroms. "
-                "Not needed if the anode-type is specified. "
+                "Not needed if the anode-type is specified."
             ),
             "type": float,
         },
@@ -101,7 +101,7 @@ def define_arguments():
                 f"The method for computing absorption correction. "
                 f"Allowed methods: {*CVE_METHODS, }. "
                 f"Default method is polynomial interpolation "
-                f"if not specified. "
+                f"if not specified."
             ),
             "default": "polynomial_interpolation",
         },
@@ -118,7 +118,7 @@ def define_arguments():
                 "For example, facility='NSLS II', "
                 "'facility=NSLS II', beamline=28ID-2, "
                 "'beamline'='28ID-2', 'favorite color'=blue, "
-                "are all valid key=value items. "
+                "are all valid key=value items."
             ),
             "nargs": "+",
             "metavar": "KEY=VALUE",
@@ -128,7 +128,7 @@ def define_arguments():
             "help": (
                 "Username will be loaded from config files. "
                 "Specify here only if you want to "
-                "override that behavior at runtime. "
+                "override that behavior at runtime."
             ),
             "default": None,
         },
@@ -137,7 +137,7 @@ def define_arguments():
             "help": (
                 "Email will be loaded from config files. "
                 "Specify here only if you want to "
-                "override that behavior at runtime. "
+                "override that behavior at runtime."
             ),
             "default": None,
         },
@@ -146,7 +146,7 @@ def define_arguments():
             "help": (
                 "ORCID will be loaded from config files. "
                 "Specify here only if you want to "
-                "override that behavior at runtime. "
+                "override that behavior at runtime."
             ),
             "default": None,
         },

Diff for: src/diffpy/labpdfproc/tools.py

@@ -161,6 +161,7 @@ def set_input_lists(args):
 
 def set_wavelength(args):
     """Set the wavelength based on the given anode_type or wavelength.
+
     First checks from args. If neither is provided,
     it attempts to load from local and then global config file.
 
@@ -173,7 +174,8 @@ def set_wavelength(args):
     ------
     ValueError
         Raised if:
-        (1) neither is provided, and either mu*D needs to be looked up or
+        (1) neither wavelength or anode type is provided,
+            and either mu*D needs to be looked up or
             xtype is not the two-theta grid,
         (2) both are provided,
         (3) anode_type is not one of the known sources,
@@ -186,7 +188,9 @@ def set_wavelength(args):
     """
     # first load values from config file
     if args.wavelength is None and args.anode_type is None:
-        if not (args.mud is not None and args.xtype in ANGLEQUANTITIES):
+        # either mu*D needs to be looked up or
+        # xtype is not the two-theta grid
+        if args.mud is None or args.xtype not in ANGLEQUANTITIES:
             raise ValueError(
                 f"Please provide a wavelength or anode type. "
                 f"Allowed anode types are {*known_sources, }."

Diff for: tests/test_tools.py

@@ -272,11 +272,13 @@ def test_set_wavelength(inputs, expected):
             f"Allowed anode types are {*known_sources, }.",
         ),
         (  # C3: invalid anode type
+            # expect error asking to specify a valid anode type
             ["--anode-type", "invalid"],
             f"Anode type not recognized. "
             f"Please rerun specifying an anode_type from {*known_sources, }.",
         ),
         (  # C4: invalid wavelength
+            # expect error asking to specify a valid wavelength or anode type
             ["--wavelength", "0"],
             "No valid wavelength. "
             "Please rerun specifying a known anode_type "
@@ -506,6 +508,11 @@ def test_load_package_info(mocker):
 
 
 def test_load_metadata(mocker, user_filesystem):
+    # Test if the function loads args
+    # (which will be loaded into the header file).
+    # Expect to include mu*D, anode type, xtype, cve method,
+    # user-specified metadata, user info, package info, z-scan file,
+    # and full paths for current input and output directories.
     cwd = Path(user_filesystem)
     home_dir = cwd / "home_dir"
     mocker.patch("pathlib.Path.home", lambda _: home_dir)