Previous editions of the test framework used a
.testsettings file to manage advance test settings such as deploying test data along with your tests. However, in 2012 Microsoft introduced a newer version of the test framework and mostly did away with the
.testsettings files. You can still use them, but if you do, your tests will be run under the old unit test framework (and thus execute more slowly; also, the older test framework does not allow tests from third-party frameworks).
The recommended solution is to use the default configuration of your unit tests whenever possible. If you need to use test configuration files, you can add them to your project from the Test menu (Test, Test Settings, Select Test Settings File). ...