Credential.connectionString

auto cred = Credential().host("localhost");
assert(cred.connectionString == "host=localhost");

cred = Credential().host("127.0.0.1").port(3306);
assert(cred.connectionString == "host=127.0.0.1;port=3306");

cred = Credential().host("localhost").user("testuser").db("SchemaXY");
assert(cred.connectionString == "host=localhost;user=testuser;db=SchemaXY");
assert(cred.host == "localhost");