fix: no pool preds for random heuristic (#277)

* fix: no pool preds for random heuristic

* use isinstance() instead of __name__ attribute

* test: add test for get_probabilities with Random

---------

Co-authored-by: Frédéric Branchaud-Charron <frederic.branchaud.charron@gmail.com>

baal/active/active_loop.py

@@ -79,7 +79,10 @@ def step(self, pool=None) -> bool:
             indices = None
 
         if len(pool) > 0:
-            probs = self.get_probabilities(pool, **self.kwargs)
+            if isinstance(self.heuristic, heuristics.Random):
+                probs = np.random.uniform(low=0, high=1, size=(len(pool), 1))
+            else:
+                probs = self.get_probabilities(pool, **self.kwargs)
             if probs is not None and (isinstance(probs, types.GeneratorType) or len(probs) > 0):
                 to_label, uncertainty = self.heuristic.get_ranks(probs)
                 if indices is not None:

tests/active/active_loop_test.py

@@ -1,6 +1,7 @@
 import os
 import pickle
 import warnings
+from unittest.mock import patch
 
 import numpy as np
 import pytest
@@ -140,5 +141,24 @@ def test_deprecation():
         assert issubclass(w[-1].category, DeprecationWarning)
         assert "ndata_to_label" in str(w[-1].message)
 
+
+@pytest.mark.parametrize('heur,num_get_probs', [(heuristics.Random(), 0),
+                                  (heuristics.BALD(), 1),
+                                  (heuristics.Entropy(), 1),
+                                  (heuristics.Variance(reduction='sum'), 1)
+                                  ])
+def test_get_probs(heur, num_get_probs):
+    dataset = ActiveLearningDataset(MyDataset(), make_unlabelled=lambda x: -1)
+    active_loop = ActiveLearningLoop(dataset,
+                                    get_probs_iter,
+                                    heur,
+                                    query_size=5,
+                                    dummy_param=1)
+    dataset.label_randomly(10)
+    with patch.object(active_loop, "get_probabilities") as mock_probs:
+        active_loop.step()
+    assert mock_probs.call_count == num_get_probs
+
+
 if __name__ == '__main__':
     pytest.main()