Make large results display quickly by loading them in pieces.

tests/paged_list_test.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python3.7
+
+# Copyright (C) 2019 Andrew Hamilton. All rights reserved.
+# Licensed under the Artistic License 2.0.
+
+
+import pickle
+import tempfile
+import unittest
+
+import eris.paged_list as paged_list
+
+
+class PagedListTestCase(unittest.TestCase):
+
+    def test_getitem(self):
+        with tempfile.TemporaryDirectory() as temp_dir:
+            list_ = paged_list.PagedList([3, 4, 5, 6], temp_dir, 4, 2)
+            self.assertEqual(list_[1], 4)            
+            self.assertEqual(list_[1:3], [4, 5])
+            self.assertEqual(list_[0:4], [3, 4, 5, 6])        
+        with tempfile.TemporaryDirectory() as temp_dir:
+            list_ = paged_list.PagedList([3, 4, 5, 6], temp_dir, 2, 2)
+            self.assertEqual(list_[1:3], [4, 5])
+        with tempfile.TemporaryDirectory() as temp_dir:
+            list_ = paged_list.PagedList([3, 4, 5, 6, 7, 8], temp_dir, 2, 2)
+            self.assertEqual(list_[1:5], [4, 5, 6, 7])
+            self.assertEqual(list_[:2], [3, 4])
+            self.assertEqual(list_[2:], [5, 6, 7, 8])
+
+    def test_pickling(self):
+        with tempfile.TemporaryDirectory() as temp_dir:
+            list_ = paged_list.PagedList([3, 4, 5], temp_dir, 2, 2)
+            list_b = pickle.loads(pickle.dumps(list_))
+            self.assertEqual(list_b[1], 4)
+
+
+if __name__ == "__main__":
+    unittest.main()