Add new munge_lists function + unit test

lib/galaxy/util/__init__.py

@@ -1882,3 +1882,14 @@ def enum_values(enum_class):
     Values are in member definition order.
     """
     return [value.value for value in enum_class.__members__.values()]
+
+
+def munge_lists(listA: Any, listB: Any) -> List:
+    """
+    Combine two lists into a single list.
+
+    Arguments can be None, non-lists, or lists. If an argument is None, it will
+    not be included in the returned list. If both arguments are None, an empty
+    list will be returned.
+    """
+    return listify(listA) + listify(listB)

test/unit/util/test_utils.py

@@ -149,3 +149,20 @@ def test_enum_values():
         B = "b"
 
     assert util.enum_values(Stuff) == ["a", "c", "b"]
+
+
+class NotFalsy:
+    """Class requires explicit check for None"""
+
+    def __bool__(self):
+        raise Exception("not implemented")
+
+
+def test_munge_lists():
+    foo, bar = NotFalsy(), NotFalsy()
+    assert util.munge_lists(foo, None) == [foo]
+    assert util.munge_lists(None, foo) == [foo]
+    assert util.munge_lists(foo, bar) == [foo, bar]
+    assert util.munge_lists([foo, bar], None) == [foo, bar]
+    assert util.munge_lists(None, [foo, bar]) == [foo, bar]
+    assert util.munge_lists(None, None) == []