Add unit tests to check that sharing map modifications do not invalidate views

This adds unit tests to check that the references into the sharing map in the
views and delta views remain valid after operations erase(), insert(), and
replace(). The references should remain valid to those elements that are not
changed by the respective operations.

Author: danpoe

unit/util/sharing_map.cpp

@@ -439,6 +439,98 @@ TEST_CASE("Sharing map views and iteration", "[core][util]")
   }
 }
 
+TEST_CASE("Sharing map view validity", "[core][util]")
+{
+  SECTION("View validity")
+  {
+    sharing_map_standardt sm;
+    sharing_map_standardt::viewt view;
+
+    fill(sm);
+    fill2(sm);
+
+    sharing_map_standardt sm2(sm);
+    sm2.replace("l", "8");
+
+    sm.get_view(view);
+
+    std::size_t i_idx = 0;
+    std::size_t k_idx = 0;
+
+    for(std::size_t i = 0; i < view.size(); i++)
+    {
+      if(view[i].first == "i")
+        i_idx = i;
+
+      if(view[i].first == "k")
+        k_idx = i;
+    }
+
+    sm.erase("i");
+    sm.replace("k", "7");
+    sm.insert("o", "6");
+
+    for(std::size_t i = 0; i < view.size(); i++)
+    {
+      if(i == i_idx || i == k_idx)
+        continue;
+
+      auto &p = view[i];
+
+      REQUIRE(&p.second == &sm.find(p.first)->get());
+    }
+  }
+
+  SECTION("Delta view validity")
+  {
+    sharing_map_standardt sm;
+
+    sharing_map_standardt::delta_viewt delta_view;
+
+    fill(sm);
+    fill2(sm);
+
+    sharing_map_standardt sm2(sm);
+
+    sm2.erase("i");
+    sm2.erase("j");
+    sm2.erase("k");
+
+    sm2.erase("m");
+    sm2.erase("n");
+
+    sm.get_delta_view(sm2, delta_view, false);
+
+    REQUIRE(delta_view.size() == 5);
+
+    std::size_t i_idx = 0;
+    std::size_t k_idx = 0;
+
+    for(std::size_t i = 0; i < delta_view.size(); i++)
+    {
+      if(delta_view[i].k == "i")
+        i_idx = i;
+
+      if(delta_view[i].k == "k")
+        k_idx = i;
+    }
+
+    sm.erase("i");
+    sm.replace("k", "7");
+    sm.insert("o", "6");
+
+    for(std::size_t i = 0; i < delta_view.size(); i++)
+    {
+      if(i == i_idx || i == k_idx)
+        continue;
+
+      auto &delta_item = delta_view[i];
+
+      REQUIRE(&delta_item.m == &sm.find(delta_item.k)->get());
+    }
+  }
+}
+
 TEST_CASE("Sharing map sharing stats", "[core][util]")
 {
 #if !defined(_MSC_VER)