Attempt to test for #4

PyTorch's boolean comparison crap isn't useful and makes
  it a pain to test exact tensor values.
* Will resume later

morph/layers/sparse_test.py

@@ -0,0 +1,15 @@
+from unittest import main as test_main, TestCase
+
+from .sparse import sparsify, torch
+
+class TestSparseFunctions(TestCase):
+
+    def test_sparsify_selected_indices_should_have_sub_threshold_values(self):
+        test_threshold = 0.1
+        test_tensor = torch.randn(3, 2)
+        expected = torch.where(test_tensor > test_threshold, test_tensor, torch.zeros(3, 2))
+        self.assertEqual(expected, sparsify(test_tensor, test_threshold))
+
+
+if __name__ == "__main__":
+    test_main()