title: How to `go test` all tests in my project?
body: <p>The <code>go test</code> command covers <code>*_test.go</code> files in only one dir.</p>
  <p>I want to <code>go test</code> the whole project, which means the test should cover all <code>*_test.go</code> files in the dir <code>./</code> and every children tree dir under the dir <code>./</code>.</p>
  <p>What's the command to do this?</p>