add todo for density test

Author: LarsKue

tests/test_networks/test_inference_networks.py

@@ -25,7 +25,9 @@ def test_build(inference_network, random_samples, random_conditions):
 
 def test_variable_batch_size(inference_network, random_samples, random_conditions):
     # build with one batch size
-    inference_network(random_samples, conditions=random_conditions)
+    samples_shape = keras.ops.shape(random_samples)
+    conditions_shape = keras.ops.shape(random_conditions) if random_conditions is not None else None
+    inference_network.build(samples_shape, conditions_shape=conditions_shape)
 
     # run with another batch size
     batch_sizes = np.random.choice(10, replace=False, size=3)
@@ -81,6 +83,7 @@ def test_cycle_consistency(inference_network, random_samples, random_conditions)
     assert allclose(forward_log_density, inverse_log_density, atol=1e-3, rtol=1e-3)
 
 
+# TODO: make this backend-agnostic
 @pytest.mark.torch
 def test_density_numerically(inference_network, random_samples, random_conditions):
     import torch