Improve error handling when importing fuel handlers

armi/physics/fuelCycle/__init__.py

@@ -173,6 +173,17 @@ def defineSettingsValidators(inspector):
         Implementation of settings inspections for fuel cycle settings.
         """
         queries = []
+
+        queries.append(settingsValidation.Query(
+                lambda: bool(inspector.cs["shuffleLogic"]) ^
+                bool(inspector.cs["fuelHandlerName"]),
+                "A value was provided for `fuelHandlerName` or `shuffleLogic`, but not "
+                "the other. Either both `fuelHandlerName` and `shuffleLogic` should be "
+                "defined, or neither of them.",
+                "",
+                inspector.NO_ACTION,
+            ))
+
         # Check for code fixes for input code on the fuel shuffling outside the version control of ARMI
         # These are basically auto-migrations for untracked code using
         # the ARMI API. (This may make sense at a higher level)

armi/physics/fuelCycle/fuelHandlers.py

@@ -224,7 +224,7 @@ def fuelHandlerFactory(operator):
 
     # User did request a custom fuel handler. We must go find and import it
     # from the input directory.
-    with directoryChangers.DirectoryChanger(cs.inputDirectory):
+    with directoryChangers.DirectoryChanger(cs.inputDirectory, dumpOnException=False):
         try:
             module = pathTools.importCustomPyModule(fuelHandlerModulePath)
 

armi/utils/pathTools.py

@@ -163,18 +163,18 @@ def getModAndClassFromPath(path):
 def separateModuleAndAttribute(pathAttr):
     """
     Return True of the specified python module, and attribute of the module exist.
-    
-    
+
+
     Parameters
     ----------
     pathAttr : str
         Path to a python module followed by the desired attribute.
         e.g.: `/path/to/my/thing.py:MyClass`
-    
+
     Notes
     -----
     The attribute of the module could be a class, function, variable, etc.
-    
+
     Raises
     ------
     ValueError:
@@ -190,17 +190,20 @@ def separateModuleAndAttribute(pathAttr):
 def importCustomPyModule(modulePath):
     """
     Dynamically import a custom module.
-    
+
     Parameters
     ----------
     modulePath : str
         Path to a python module.
-        
+
     Returns
     -------
     userSpecifiedModule : module
         The imported python module.
     """
+    modulePath = pathlib.Path(modulePath)
+    if not modulePath.exists() or not modulePath.is_file():
+        raise IOError(r"Cannot import module from the given path: `{modulePath}`")
     _dir, moduleName = os.path.split(modulePath)
     moduleName = os.path.splitext(moduleName)[0]  # take off the extension
     spec = importlib.util.spec_from_file_location(moduleName, modulePath)
@@ -212,19 +215,19 @@ def importCustomPyModule(modulePath):
 def moduleAndAttributeExist(pathAttr):
     """
     Return True if the specified python module, and attribute of the module exist.
-    
-    
+
+
     Parameters
     ----------
     pathAttr : str
         Path to a python module followed by the desired attribute.
         e.g.: `/path/to/my/thing.py:MyClass`
-        
-    Returns 
+
+    Returns
     -------
-    bool 
+    bool
         True if the specified python module, and attribute of the module exist.
-    
+
     Notes
     -----
     The attribute of the module could be a class, function, variable, etc.