title: Why am I getting "no tests to run" despite having a test function?
body: <p>Go newbie here, I have written a simple main_test.go file to run some test cases for main.go, when I run <code>go test</code> it says testing: warning: no tests to run
  PASS
  ok      Solution    0.878s</p>
  <p>my main.go:</p>
  <pre><code>package main
  
  func normalizePhoneNum(phoneNumber string) string {
      return &quot;&quot;
  }
  
  func main() {
  
  }
  </code></pre>
  <p>main_test.go:</p>
  <pre><code>package main
  
  import (
      &quot;testing&quot;
  )
  
  func testNormalizePhoneNum(t *testing.T) {
      testCase := []struct {
          input  string
          output string
      }{
          {&quot;1234567890&quot;, &quot;1234567890&quot;},
          {&quot;123 456 7891&quot;, &quot;123 456 7891&quot;},
          {&quot;(123) 456 7892&quot;, &quot;(123) 456 7892&quot;},
          {&quot;(123) 456-7893&quot;, &quot;(123) 456-7893&quot;},
          {&quot;123-456-7894&quot;, &quot;123-456-7894&quot;},
          {&quot;123-456-7890&quot;, &quot;123-456-7890&quot;},
          {&quot;1234567892&quot;, &quot;1234567892&quot;},
          {&quot;(123)456-7892&quot;, &quot;(123)456-7892&quot;},
      }
      for _, tc := range testCase {
          t.Run(tc.input, func(t *testing.T) {
              actual := normalizePhoneNum(tc.input)
              if actual != tc.output {
                  t.Errorf(&quot;for %s: got %s, expected %s&quot;, tc.input, actual, tc.output)
              }
          })
      }
  }
  </code></pre>
  <p>Can anyone please tell, why it's not running the test cases?</p>