WT-2291: Add a test case to ensure that the random walk is reasonably random.

It is currently failing. The test is currently targeted at small
in-memory trees (i.e: the skiplist random code).

1 files changed, 71 insertions, 0 deletions

diff --git a/test/suite/test_cursor_random02.py b/test/suite/test_cursor_random02.py
new file mode 100644
index 00000000000..1b684b411bc
--- /dev/null
+++ b/test/suite/test_cursor_random02.py
@@ -0,0 +1,71 @@
+#!/usr/bin/env python
+#
+# Public Domain 2014-2015 MongoDB, Inc.
+# Public Domain 2008-2014 WiredTiger, Inc.
+#
+# This is free and unencumbered software released into the public domain.
+#
+# Anyone is free to copy, modify, publish, use, compile, sell, or
+# distribute this software, either in source code form or as a compiled
+# binary, for any purpose, commercial or non-commercial, and by any
+# means.
+#
+# In jurisdictions that recognize copyright laws, the author or authors
+# of this software dedicate any and all copyright interest in the
+# software to the public domain. We make this dedication for the benefit
+# of the public at large and to the detriment of our heirs and
+# successors. We intend this dedication to be an overt act of
+# relinquishment in perpetuity of all present and future rights to this
+# software under copyright law.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+# IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+# OTHER DEALINGS IN THE SOFTWARE.
+
+import wiredtiger, wttest
+from helper import complex_populate, simple_populate
+from helper import key_populate, value_populate
+from wtscenario import check_scenarios, multiply_scenarios, number_scenarios
+
+# test_cursor_random02.py
+#    Cursor next_random operations
+class test_cursor_random02(wttest.WiredTigerTestCase):
+    type = 'table:random'
+    config = [
+        ('not-sample', dict(config='next_random=true'))
+    ]
+    scenarios = number_scenarios(config)
+
+    # Check that next_random works in the presence of a larger set of values,
+    # where the values are in an insert list.
+    def test_cursor_random_reasonable_distribution(self):
+        uri = self.type
+        num_entries = 5000
+        simple_populate(self, uri, 'key_format=S', num_entries)
+        # Setup an array to track which keys are seen
+        visitedKeys = [0] * num_entries
+
+        cursor = self.session.open_cursor(uri, None, 'next_random=true')
+        for i in range(1,num_entries):
+            self.assertEqual(cursor.next(), 0)
+            current = cursor.get_key()
+            current = int(current)
+            visitedKeys[current] = visitedKeys[current] + 1
+
+            if i % 8 == 0:
+                cursor.close()
+                cursor = self.session.open_cursor(uri, None, 'next_random=true')
+
+        differentKeys = sum(x > 0 for x in visitedKeys)
+        #print visitedKeys
+        #print differentKeys
+        self.assertGreater(differentKeys, num_entries / 4,
+            'next_random random distribution not adequate')
+
+if __name__ == '__main__':
+    wttest.run()
+