package main

import (
	"testing"
	"unicode/utf8"
)

// unit test
/*
func TestReverse(t *testing.T) {
  testcases := []struct {
    in, want string
  }{
    {"Hello, World", "dlroW ,olleH"},
    {" ", " "},
    {"!12345", "54321!"},// Go insists on the , !
  }
  for _, tc := range testcases {
    rev := Reverse(tc.in)
    if rev != tc.want {
      t.Errorf("Reverse: %q, want %q", rev,tc.want)
    }
  
  }
}
*/


// fuzzing allows me to generate more test cases with less work.
// function prototype begins FuzzXxxx and takes *testing.F instead of *testing.T
func FuzzReverse(f *testing.F) {
  testcases := []string{"Hello, world", " ", "!12345"}
  for _, tc := range testcases {
    f.Add(tc)
  }
  f.Fuzz(func(t *testing.T, orig string) {
    rev, err1 := Reverse(orig)
    if err1 != nil {
      return
    }
    doubleRev, err2 := Reverse(rev)
    if err2 != nil {
      return
    }
    t.Logf("Number of runes: orig=%d, rev=%d, doubleRev=%d",utf8.RuneCountInString(orig), utf8.RuneCountInString(rev), utf8.RuneCountInString(doubleRev))
    if orig != doubleRev {
      t.Errorf("Before: %q, after: %q", orig, doubleRev)
    }
    if utf8.ValidString(orig) && !utf8.ValidString(rev) {
      t.Errorf("Reverse produced invalid UTF-8 string %q", rev)
    }
  })
//  f.Fuzz(func(t *testing.T, orig string) {
//    rev := Reverse(orig)
//    doubleRev := Reverse(rev)
//    if orig != doubleRev {
//      t.Errorf("Before: %q, after: %q", orig, doubleRev)
//    }
//    if utf8.ValidString(orig) && !utf8.ValidString(rev) {
//      t.Errorf("Reverse produced invalid UTF-8 string %q", rev)
//    }
//})
}