Tests: add partial_name_map_composite fixture

- the partial_name_map_composites fixture creates a random (but seeded)
  partial name_map by the actual associations (i.e. one name to one
  rule)
- this is used to correctly test MixedComposites/NameLayerMapComposites
  to fall back to the LayerMap
- add pyrng fixture, based on the same seed as the numpy RNG
- removed unneeded input fixtures for some fixtures in conftest.py

tests/conftest.py

@@ -1,5 +1,6 @@
 '''Configuration and fixtures for testing'''
-from itertools import product
+import random
+from itertools import product, groupby
 from collections import OrderedDict
 
 import pytest
@@ -50,10 +51,16 @@ def pytest_generate_tests(metafunc):
     ids=hex
 )
 def rng(request):
-    '''Random number generator fixture.'''
+    '''Fixture for the NumPy random number generator.'''
     return torch.manual_seed(request.param)
 
 
+@pytest.fixture(scope='session')
+def pyrng(rng):
+    '''Fixture for the Python random number generator.'''
+    return random.Random(rng.initial_seed())
+
+
 @pytest.fixture(
     scope='session',
     params=[
@@ -226,7 +233,7 @@ def any_composite(request):
 
 
 @pytest.fixture(scope='session')
-def name_map_composite(request, model_vision, layer_map_composite):
+def name_map_composite(model_vision, layer_map_composite):
     '''Fixture to create NameMapComposites based on explicit LayerMapComposites.'''
     rule_map = {}
     for name, child in model_vision.named_modules():
@@ -239,19 +246,33 @@ def name_map_composite(request, model_vision, layer_map_composite):
 
 
 @pytest.fixture(scope='session')
-def mixed_composite(request, model_vision, name_map_composite, special_first_layer_map_composite):
-    '''Fixture to create NameLayerMapComposites based on an explicit
-    NameMapComposite and SpecialFirstLayerMapComposites.'''
-    composites = [name_map_composite, special_first_layer_map_composite]
+def partial_name_map_composite(name_map_composite, pyrng):
+    '''Fixture to create a randomly sampled partial NameMapComposites.'''
+    name_map = name_map_composite.name_map
+    assocs = [(i, j) for i, (keys, _) in enumerate(name_map) for j in range(len(keys))]
+    accepted_assocs = sorted(pyrng.sample(assocs, len(assocs) // 2))
+    partial_name_map = [
+        (tuple(name_map[k][0][n] for _, n in g), name_map[k][1].copy())
+        for k, g in groupby(accepted_assocs, lambda o: o[0])
+    ]
+
+    return NameMapComposite(name_map=partial_name_map)
+
+
+@pytest.fixture(scope='session')
+def mixed_composite(partial_name_map_composite, special_first_layer_map_composite):
+    '''Fixture to create NameLayerMapComposites based on an explicit NameMapComposite and
+    SpecialFirstLayerMapComposites.
+    '''
+    composites = [partial_name_map_composite, special_first_layer_map_composite]
     return MixedComposite(composites)
 
 
 @pytest.fixture(scope='session')
-def name_layer_map_composite(request, model_vision, name_map_composite, layer_map_composite):
-    '''Fixture to create NameLayerMapComposites based on an explicit
-    NameMapComposite and LayerMapComposite.'''
+def name_layer_map_composite(partial_name_map_composite, layer_map_composite):
+    '''Fixture to create NameLayerMapComposites based on an explicit NameMapComposite and LayerMapComposite.'''
     return NameLayerMapComposite(
-        name_map=name_map_composite.name_map,
+        name_map=partial_name_map_composite.name_map,
         layer_map=layer_map_composite.layer_map,
     )