Golang:Testing

1. Golang Testing

This method works best when the `testCase` is a large struct, and only tiny changes are made to that struct for each case.

```go func Func(value int) {

 return value > 0

}

func TestFunc(t *testing.T) {

 type testCase struct {
   desc  string
   ok    bool
   value int
 }

 okFunc := func(changeFn func(*testCase)) testCase {
   tc := &testCase {
     ok: true,
   }
   if changeFn != nil {
     changeFn(tc)
   }
   return *tc
 }

 for _, tc := range []testCase {
   // ok values.
   okFunc(nil),
   okFunc(func(tc *testCase) {
     tc.desc = "one"
     tc.value = 1
   },
   // not-ok values.
   testCase{"not-ok"},
 }{
   if got, want := Func(tc.value), tc.ok; got != want {
     t.Errorf("%s: Func(%d) = %t", tc.desc, tc.value, got)
   }  
 }

} ```