diff --git a/mart/utils/config.py b/mart/utils/config.py
index 36dbb6e6..384f4a31 100644
--- a/mart/utils/config.py
+++ b/mart/utils/config.py
@@ -10,12 +10,13 @@
 
 from hydra import compose as hydra_compose
 from hydra import initialize_config_dir
+from hydra.utils import instantiate as hydra_instantiate
 
 DEFAULT_VERSION_BASE = "1.2"
 DEFAULT_CONFIG_DIR = "."
 DEFAULT_CONFIG_NAME = "lightning.yaml"
 
-__all__ = ["compose"]
+__all__ = ["compose", "instantiate"]
 
 
 def compose(
@@ -40,3 +41,26 @@ def compose(
             cfg = cfg[key]
 
     return cfg
+
+
+def instantiate(
+    *overrides,
+    version_base: str = DEFAULT_VERSION_BASE,
+    config_dir: str = DEFAULT_CONFIG_DIR,
+    config_name: str = DEFAULT_CONFIG_NAME,
+    export_node: str | None = None,
+):
+    """Compose and instantiate an object.
+
+    Should be useful in testing configs.
+    """
+    cfg = compose(
+        *overrides,
+        version_base=version_base,
+        config_dir=config_dir,
+        config_name=config_name,
+        export_node=export_node,
+    )
+
+    obj = hydra_instantiate(cfg)
+    return obj
diff --git a/tests/test_composer.py b/tests/test_composer.py
index 3aba543c..0b8e7021 100644
--- a/tests/test_composer.py
+++ b/tests/test_composer.py
@@ -17,6 +17,7 @@
     PerturbationRectanglePad,
     PerturbationRectanglePerspectiveTransform,
 )
+from mart.utils import instantiate
 
 
 def test_additive_composer_forward(input_data, target_data, perturbation):
@@ -125,3 +126,45 @@ def test_pert_rect_perspective_transform():
     pert_coords_expected[:, 5:, 5:] = 1
     # rounding numeric error from the perspective transformation.
     assert torch.equal(pert_coords.round(), pert_coords_expected)
+
+
+def test_rect_patch_additive_composer():
+    overrides = ["+attack/composer=rect_patch_additive"]
+    composer = instantiate(*overrides, export_node="attack.composer")
+
+    input = torch.ones((3, 10, 10))
+    perturbation = torch.ones_like(input) * 2
+
+    input_adv_expected = input.clone()
+    input_adv_expected[:, -5:, -5:] += 2
+
+    # A simple square patch on the bottom right.
+    patch_coords = torch.tensor(((5, 5), (10, 5), (10, 10), (5, 10)))
+    perturbable_mask = torch.zeros((10, 10))
+    perturbable_mask[-5:, -5:] = 1
+
+    target = {"patch_coords": patch_coords, "perturbable_mask": perturbable_mask}
+    input_adv = composer(perturbation, input=input, target=target)
+
+    assert torch.allclose(input_adv_expected, input_adv)
+
+
+def test_rect_patch_overlay_composer():
+    overrides = ["+attack/composer=rect_patch_overlay"]
+    composer = instantiate(*overrides, export_node="attack.composer")
+
+    input = torch.ones((3, 10, 10))
+    perturbation = torch.ones_like(input) * 2
+
+    input_adv_expected = input.clone()
+    input_adv_expected[:, -5:, -5:] = 2
+
+    # A simple square patch on the bottom right.
+    patch_coords = torch.tensor(((5, 5), (10, 5), (10, 10), (5, 10)))
+    perturbable_mask = torch.zeros((10, 10))
+    perturbable_mask[-5:, -5:] = 1
+
+    target = {"patch_coords": patch_coords, "perturbable_mask": perturbable_mask}
+    input_adv = composer(perturbation, input=input, target=target)
+
+    assert torch.allclose(input_adv_expected, input_adv)