tests: add tests for wallet output selection

tests/unit_tests/CMakeLists.txt

@@ -52,7 +52,8 @@ set(unit_tests_sources
   hardfork.cpp
   unbound.cpp
   varint.cpp
-  ringct.cpp)
+  ringct.cpp
+  output_selection.cpp)
 
 set(unit_tests_headers
   unit_tests_utils.h)

tests/unit_tests/output_selection.cpp

@@ -0,0 +1,98 @@
+// Copyright (c) 2014-2016, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// FIXME: move this into a full wallet2 unit test suite, if possible
+
+#include "gtest/gtest.h"
+
+#include "wallet/wallet2.h"
+#include <string>
+
+static tools::wallet2::transfer_container make_transfers_container(size_t N)
+{
+  tools::wallet2::transfer_container transfers;
+  for (size_t n = 0; n < N; ++n)
+  {
+    transfers.push_back(AUTO_VAL_INIT(tools::wallet2::transfer_details()));
+    tools::wallet2::transfer_details &td = transfers.back();
+    td.m_block_height = 1000;
+    td.m_spent = false;
+  }
+  return transfers;
+}
+
+#define SELECT(idx) \
+  do { \
+    auto i = std::find(unused_indices.begin(), unused_indices.end(), idx); \
+    ASSERT_TRUE(i != unused_indices.end()); \
+    unused_indices.erase(i); \
+    selected.push_back(transfers.begin() + idx); \
+  } while(0)
+
+#define PICK(expected) \
+  do { \
+    size_t idx = w.pop_best_value_from(transfers, unused_indices, selected); \
+    ASSERT_EQ(expected, idx); \
+    selected.push_back(transfers.begin() + idx); \
+  } while(0)
+
+TEST(select_outputs, one_out_of_N)
+{
+  tools::wallet2 w;
+
+  // check that if there are N-1 outputs of the same height, one of them
+  // already selected, the next one selected is the one that's from a
+  // different height
+  tools::wallet2::transfer_container transfers = make_transfers_container(10);
+  transfers[6].m_block_height = 700;
+  std::vector<size_t> unused_indices({0, 1, 2, 3, 4, 5, 6, 7, 8, 9});
+  std::list<tools::wallet2::transfer_container::iterator> selected;
+  SELECT(2);
+  PICK(6);
+}
+
+TEST(select_outputs, order)
+{
+  tools::wallet2 w;
+
+  // check that most unrelated heights are picked in order
+  tools::wallet2::transfer_container transfers = make_transfers_container(5);
+  transfers[0].m_block_height = 700;
+  transfers[1].m_block_height = 700;
+  transfers[2].m_block_height = 704;
+  transfers[3].m_block_height = 716;
+  transfers[4].m_block_height = 701;
+  std::vector<size_t> unused_indices({0, 1, 2, 3, 4});
+  std::list<tools::wallet2::transfer_container::iterator> selected;
+  SELECT(0);
+  PICK(3); // first the one that's far away
+  PICK(2); // then the one that's close
+  PICK(4); // then the one that's adjacent
+  PICK(1); // then the one that's on the same height
+}
+