rf: better implementation and testing of the offset feature of layers

tests/test_data/test_typing_helpers.py

@@ -0,0 +1,19 @@
+"""Tests for typing helpers"""
+
+import pytest
+
+from pytiled_parser import typing_helpers as TH
+
+TEST_IS_FLOAT_PARAMS = [
+    (1, True),
+    ("1", True),
+    (1.1, True),
+    ("1.1", True),
+    ("one", False),
+    (None, False),
+]
+
+
+@pytest.mark.parametrize("string,expected", TEST_IS_FLOAT_PARAMS)
+def test_is_float(string, expected):
+    assert TH.is_float(string) == expected