message: Less arbitrary test
diff: @@ -98,8 +98,8 @@ BOOST_AUTO_TEST_CASE(collapse) {
  // o---o
  // 0 3
  edges.emplace_back(0, 2, 2.);
  - edges.emplace_back(1, 3, 2.);
  - trace_and_check_collapse(edges, {{1, 3, 2.}});
  + edges.emplace_back(1, 3, 2.1);
  + trace_and_check_collapse(edges, {{1, 3, 2.1}});
  // 1 2 4
  // o---o---o
  @@ -121,8 +121,8 @@ BOOST_AUTO_TEST_CASE(collapse) {
  // o---o---o
  // 0 3 5
  edges.emplace_back(2, 5, 4.);
  - edges.emplace_back(4, 3, 4.);
  - trace_and_check_collapse(edges, {{1, 3, 2.}, {4, 3, 4.}});
  + edges.emplace_back(4, 3, 4.1);
  + trace_and_check_collapse(edges, {{1, 3, 2.}, {4, 3, 4.1}});
  // 1 2 4
  // o---o---o
  @@ -132,8 +132,8 @@ BOOST_AUTO_TEST_CASE(collapse) {
  // o---o---o
  // 0 3 5
  edges.emplace_back(1, 5, 5.);
  - edges.emplace_back(0, 4, 5.);
  - trace_and_check_collapse(edges, {{1, 3, 2.}, {4, 3, 4.}, {0, 4, 5.}});
  + edges.emplace_back(0, 4, 5.1);
  + trace_and_check_collapse(edges, {{1, 3, 2.}, {4, 3, 4.}, {0, 4, 5.1}});
  }
  BOOST_AUTO_TEST_CASE(collapse_from_array) {
  @@ -150,8 +150,8 @@ BOOST_AUTO_TEST_CASE(collapse_from_array) {
  {2, 3, 1.},
  {3, 0, 1.},
  {0, 2, 2.},
  - {1, 3, 2.}}};
  - trace_and_check_collapse(f_edge_array, {{1, 3, 2.}});
  + {1, 3, 2.1}}};
  + trace_and_check_collapse(f_edge_array, {{1, 3, 2.1}});
  }
  BOOST_AUTO_TEST_CASE(collapse_from_proximity_graph) {
  