message: Refactor: Remove using namespace <xxx> from /dbwrapper_tests
  backports (partially) bitcoin@73f41190b91dce9c125b1828b18f7625e0200145
diff: #include <boost/assert.hpp>
  #include <boost/test/unit_test.hpp>
  -using namespace std;
  -using namespace boost::assign; // bring 'operator+=()' into scope
  -using namespace boost::filesystem;
  // Test if a string consists entirely of null characters
  -bool is_null_key(const vector<unsigned char>& key) {
  +bool is_null_key(const std::vector<unsigned char>& key) {
  bool isnull = true;
  for (unsigned int i = 0; i < key.size(); i++)
  @@ -30,7 +27,7 @@ BOOST_FIXTURE_TEST_SUITE(dbwrapper_tests, BasicTestingSetup)
  BOOST_AUTO_TEST_CASE(dbwrapper)
  {
  {
  - path ph = temp_directory_path() / unique_path();
  + boost::filesystem::path ph = boost::filesystem::temp_directory_path() / boost::filesystem::unique_path();
  CDBWrapper dbw(ph, (1 << 20), true, false);
  char key = 'k';
  uint256 in = GetRandHash();
  @@ -46,7 +43,7 @@ BOOST_AUTO_TEST_CASE(dbwrapper)
  BOOST_AUTO_TEST_CASE(dbwrapper_batch)
  {
  {
  - path ph = temp_directory_path() / unique_path();
  + boost::filesystem::path ph = boost::filesystem::temp_directory_path() / boost::filesystem::unique_path();
  CDBWrapper dbw(ph, (1 << 20), true, false);
  char key = 'i';
  @@ -81,7 +78,7 @@ BOOST_AUTO_TEST_CASE(dbwrapper_batch)
  BOOST_AUTO_TEST_CASE(dbwrapper_iterator)
  {
  {
  - path ph = temp_directory_path() / unique_path();
  + boost::filesystem::path ph = boost::filesystem::temp_directory_path() / boost::filesystem::unique_path();
  CDBWrapper dbw(ph, (1 << 20), true, false);
  // The two keys are intentionally chosen for ordering
  