make tests a proper package and add pytest config

adaptive/tests/test_leaner.py → adaptive/tests/test_learner.py

 # -*- coding: utf-8 -*-
-import adaptive
 
-def test_neigbors():
-    learner = adaptive.learner.Learner1D(lambda x: x, bounds=(-1.0, 1.0))
+from ..learner import Learner1D
+
+
+def test_neighbors():
+    learner = Learner1D(lambda x: x, bounds=(-1.0, 1.0))
     learner.add_data([-1, 1], [-1, 1])
     assert learner.neighbors == {-1: [None, 1], 1: [-1, None]}
     learner.choose_points(1, False)

pytest.ini

+[pytest]
+testpaths = adaptive