[DeferredDict] implement get/items/values for deferreddict

masque/test/test_utils.py

@@ -2,7 +2,7 @@ import numpy
 from numpy.testing import assert_equal, assert_allclose
 from numpy import pi
 
-from ..utils import remove_duplicate_vertices, remove_colinear_vertices, poly_contains_points, rotation_matrix_2d, apply_transforms
+from ..utils import remove_duplicate_vertices, remove_colinear_vertices, poly_contains_points, rotation_matrix_2d, apply_transforms, DeferredDict
 
 
 def test_remove_duplicate_vertices() -> None:
@@ -86,3 +86,21 @@ def test_apply_transforms_advanced() -> None:
     # 2. rotate by outer rotation (pi/2): (10, 0) -> (0, 10)
     # 3. add outer offset (0, 0) -> (0, 10)
     assert_allclose(combined[0], [0, 10, pi / 2, 1, 1], atol=1e-10)
+
+
+def test_deferred_dict_accessors_resolve_values_once() -> None:
+    calls = 0
+
+    def make_value() -> int:
+        nonlocal calls
+        calls += 1
+        return 7
+
+    deferred = DeferredDict[str, int]()
+    deferred["x"] = make_value
+
+    assert deferred.get("missing", 9) == 9
+    assert deferred.get("x") == 7
+    assert list(deferred.values()) == [7]
+    assert list(deferred.items()) == [("x", 7)]
+    assert calls == 1