bring back missing test

tests/cartesian_tests/integration_tests/multi_feature_tests/test_debug_backend.py

@@ -395,3 +395,28 @@ def test_stencil(
     test_stencil(field_in, field_out)
 
     np.testing.assert_allclose(field_out.view(np.ndarray)[:, :, 1], 1)
+
+
+def test_this_k_function():
+    field_in = gt_storage.ones(
+        dtype=np.float64, backend="debug", shape=(4, 4, 4), aligned_index=(0, 0, 0)
+    )
+    field_out = gt_storage.zeros(
+        dtype=np.float64, backend="debug", shape=(4, 4, 4), aligned_index=(0, 0, 0)
+    )
+
+    @gtscript.function
+    def this_k_function(in_field: gtscript.Field[np.float64]):
+        return in_field.at(K=THIS_K)
+
+    @gtscript.stencil(backend="debug")
+    def test_stencil(
+        in_field: gtscript.Field[np.float64],
+        out_field: gtscript.Field[np.float64],
+    ):
+        with computation(PARALLEL), interval(...):
+            out_field[0, 0, 0] = this_k_function(in_field)
+
+    test_stencil(field_in, field_out)
+
+    np.testing.assert_allclose(field_out.view(np.ndarray)[:, :, :], 1)