message: Add test cases for iterator to const iterator assignment
diff: @@ -1519,48 +1519,64 @@ TEST_CASE("iterators 1")
  json j = true;
  json::const_iterator it = j.begin();
  CHECK(it == j.cbegin());
  + it = j.begin();
  + CHECK(it == j.cbegin());
  }
  SECTION("string")
  {
  json j = "hello world";
  json::const_iterator it = j.begin();
  CHECK(it == j.cbegin());
  + it = j.begin();
  + CHECK(it == j.cbegin());
  }
  SECTION("array")
  {
  json j = {1, 2, 3};
  json::const_iterator it = j.begin();
  CHECK(it == j.cbegin());
  + it = j.begin();
  + CHECK(it == j.cbegin());
  }
  SECTION("object")
  {
  json j = {{"A", 1}, {"B", 2}, {"C", 3}};
  json::const_iterator it = j.begin();
  CHECK(it == j.cbegin());
  + it = j.begin();
  + CHECK(it == j.cbegin());
  }
  SECTION("number (integer)")
  {
  json j = 23;
  json::const_iterator it = j.begin();
  CHECK(it == j.cbegin());
  + it = j.begin();
  + CHECK(it == j.cbegin());
  }
  SECTION("number (unsigned)")
  {
  json j = 23u;
  json::const_iterator it = j.begin();
  CHECK(it == j.cbegin());
  + it = j.begin();
  + CHECK(it == j.cbegin());
  }
  SECTION("number (float)")
  {
  json j = 23.42;
  json::const_iterator it = j.begin();
  CHECK(it == j.cbegin());
  + it = j.begin();
  + CHECK(it == j.cbegin());
  }
  SECTION("null")
  {
  json j = nullptr;
  json::const_iterator it = j.begin();
  CHECK(it == j.cbegin());
  + it = j.begin();
  + CHECK(it == j.cbegin());
  }
  }
  }
  