TST(transformers): Extend typecast unittests a little.

unittests/test_transformers.py

@@ -168,20 +168,22 @@ def test_cast_transformer_functions():
     for val in ("True", "true", "False", "false"):
         assert type(cast_to_bool(val, {})) == bool
         if val[1] == "r":
-            assert cast_to_bool(val, {})
+            assert cast_to_bool(val, {}) is True
         else:
-            assert not cast_to_bool(val, {})
+            assert cast_to_bool(val, {}) is False
     for val_err in ("jaksdlfj", "0", 1):
         with pytest.raises(ValueError):
             cast_to_bool(val_err, {})
-    assert not cast_to_bool(False, {})
-    assert cast_to_bool(True, {})
+    assert cast_to_bool(False, {}) is False
+    assert cast_to_bool(True, {}) is True
 
     assert cast_to_int("24", {}) == 24
     assert cast_to_int(24.0, {}) == 24
     assert cast_to_int(24, {}) == 24
+    assert cast_to_int("-24", {}) == -24
     with pytest.raises(ValueError):
         cast_to_int("24dsf", {})
+    with pytest.raises(ValueError):
         cast_to_int("24.0", {}) == 24
 
     assert cast_to_float("24", {}) == 24.0