Optionally ignore Nones when checking the type of list contents.

src/biocutils/is_list_of_type.py

@@ -1,21 +1,28 @@
-from typing import Any
+from typing import Any, Callable, Union
 
 __author__ = "jkanche"
 __copyright__ = "jkanche"
 __license__ = "MIT"
 
 
-def is_list_of_type(x: Any, target_type) -> bool:
+def is_list_of_type(x: Union[list, tuple], target_type: Callable, ignore_none: bool = False) -> bool:
     """Checks if ``x`` is a list, and whether all elements of the list are of the same type.
 
     Args:
-        x (Any): Any list-like object.
-        target_type (callable): Type to check for, e.g. ``str``, ``int``.
+        x: A list or tuple of values.
+
+        target_type: Type to check for, e.g. ``str``, ``int``.
+
+        ignore_none: Whether to ignore Nones when comparing to ``target_type``.
 
     Returns:
-        bool: True if ``x`` is :py:class:`list` or :py:class:`tuple` and
-        all elements are of the same type.
+        True if ``x`` is a list or tuple and all elements are of the target
+        type (or None, if ``ignore_none = True``). Otherwise, false.
     """
-    return isinstance(x, (list, tuple)) and all(
-        isinstance(item, target_type) for item in x
-    )
+    if not isinstance(x, (list, tuple)):
+        return False
+
+    if not ignore_none:
+        return all(isinstance(item, target_type) for item in x)
+
+    return all((isinstance(item, target_type) or item is None) for item in x)

tests/test_list_type_checks.py

@@ -14,6 +14,10 @@ def test_simple_list():
     xt = (1, 2, 3)
     assert is_list_of_type(xt, int)
 
+    xt = (1, 2, None)
+    assert not is_list_of_type(xt, int)
+    assert is_list_of_type(xt, int, ignore_none = True)
+
 
 def test_should_fail():
     x = [1, [2, 3, 4], 6]