GO语言（十八）模糊测试入门（下）

　　修复错误
　　Reverse为了解决这个问题，如果输入不是有效的 UTF-8 ，让我们返回一个错误。
　　1、编写代码
　　a.在您的文本编辑器中，将现有Reverse函数替换为以下内容。 func Reverse(s string) (string, error) {     if !utf8.ValidString(s) {         return s, errors.New(＂input is not valid UTF-8＂)     }     r := []rune(s)     for i, j := 0, len(r)-1; i < len(r)/2; i, j = i+1, j-1 {         r[i], r[j] = r[j], r[i]     }     return string(r), nil }
　　如果输入字符串包含无效的 UTF-8 字符，此更改将返回错误。
　　b.由于 Reverse 函数现在返回错误，因此修改main函数以丢弃额外的错误值。将现有main功能替换为以下内容。 func main() {     input := ＂The quick brown fox jumped over the lazy dog＂     rev, revErr := Reverse(input)     doubleRev, doubleRevErr := Reverse(rev)     fmt.Printf(＂original: %q ＂, input)     fmt.Printf(＂reversed: %q, err: %v ＂, rev, revErr)     fmt.Printf(＂reversed again: %q, err: %v ＂, doubleRev, doubleRevErr) }
　　这些调用Reverse应该返回一个 nil 错误，因为输入字符串是有效的 UTF-8。
　　c.您将需要导入错误和 unicode/utf8 包。main.go 中的 import 语句应如下所示。 import (     ＂errors＂     ＂fmt＂     ＂unicode/utf8＂ )
　　d.修改reverse_test.go文件检查是否有错误，如果返回产生错误则跳过测试。 func FuzzReverse(f *testing.F) {     testcases := []string {＂Hello, world＂, ＂ ＂, ＂!12345＂}     for _, tc := range testcases {         f.Add(tc)  // Use f.Add to provide a seed corpus     }     f.Fuzz(func(t *testing.T, orig string) {         rev, err1 := Reverse(orig)         if err1 != nil {             return         }         doubleRev, err2 := Reverse(rev)         if err2 != nil {              return         }         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)         }     }) }
　　除了返回之外，您还可以调用t.Skip()以停止执行该模糊输入。
　　2、运行代码
　　a.使用 go test 运行测试 $ go test PASS ok      example/fuzz  0.019s
　　b.使用go test -fuzz=Fuzz进行模糊测试，几秒钟后，停止用ctrl-C模糊测试。 $ go test -fuzz=Fuzz fuzz: elapsed: 0s, gathering baseline coverage: 0/38 completed fuzz: elapsed: 0s, gathering baseline coverage: 38/38 completed, now fuzzing with 4 workers fuzz: elapsed: 3s, execs: 86342 (28778/sec), new interesting: 2 (total: 35) fuzz: elapsed: 6s, execs: 193490 (35714/sec), new interesting: 4 (total: 37) fuzz: elapsed: 9s, execs: 304390 (36961/sec), new interesting: 4 (total: 37) ... fuzz: elapsed: 3m45s, execs: 7246222 (32357/sec), new interesting: 8 (total: 41) ^Cfuzz: elapsed: 3m48s, execs: 7335316 (31648/sec), new interesting: 8 (total: 41) PASS ok      example/fuzz  228.000s
　　除非您通过-fuzztime标志进行限制，否则模糊测试将一直运行，直到遇到失败的输入。如果没有发生故障，默认是永远运行，并且可以使用 中断该过程ctrl-C。
　　c.使用go test -fuzz=Fuzz -fuzztime 30s。如果没有30 秒发现失败，它会在退出模糊测试。 $ go test -fuzz=Fuzz -fuzztime 30s fuzz: elapsed: 0s, gathering baseline coverage: 0/5 completed fuzz: elapsed: 0s, gathering baseline coverage: 5/5 completed, now fuzzing with 4 workers fuzz: elapsed: 3s, execs: 80290 (26763/sec), new interesting: 12 (total: 12) fuzz: elapsed: 6s, execs: 210803 (43501/sec), new interesting: 14 (total: 14) fuzz: elapsed: 9s, execs: 292882 (27360/sec), new interesting: 14 (total: 14) fuzz: elapsed: 12s, execs: 371872 (26329/sec), new interesting: 14 (total: 14) fuzz: elapsed: 15s, execs: 517169 (48433/sec), new interesting: 15 (total: 15) fuzz: elapsed: 18s, execs: 663276 (48699/sec), new interesting: 15 (total: 15) fuzz: elapsed: 21s, execs: 771698 (36143/sec), new interesting: 15 (total: 15) fuzz: elapsed: 24s, execs: 924768 (50990/sec), new interesting: 16 (total: 16) fuzz: elapsed: 27s, execs: 1082025 (52427/sec), new interesting: 17 (total: 17) fuzz: elapsed: 30s, execs: 1172817 (30281/sec), new interesting: 17 (total: 17) fuzz: elapsed: 31s, execs: 1172817 (0/sec), new interesting: 17 (total: 17) PASS ok      example/fuzz  31.025s
　　模糊测试通过了！
　　结论
　　做得很好！您刚刚学习了在 Go 中进行模糊测试。
　　完成的代码
　　— main.go — package main  import (     ＂errors＂     ＂fmt＂     ＂unicode/utf8＂ )  func main() {     input := ＂The quick brown fox jumped over the lazy dog＂     rev, revErr := Reverse(input)     doubleRev, doubleRevErr := Reverse(rev)     fmt.Printf(＂original: %q ＂, input)     fmt.Printf(＂reversed: %q, err: %v ＂, rev, revErr)     fmt.Printf(＂reversed again: %q, err: %v ＂, doubleRev, doubleRevErr) }  func Reverse(s string) (string, error) {     if !utf8.ValidString(s) {         return s, errors.New(＂input is not valid UTF-8＂)     }     r := []rune(s)     for i, j := 0, len(r)-1; i < len(r)/2; i, j = i+1, j-1 {         r[i], r[j] = r[j], r[i]     }     return string(r), nil }
　　— reverse_test.go — package main  import (     ＂testing＂     ＂unicode/utf8＂ )  func FuzzReverse(f *testing.F) {     testcases := []string{＂Hello, world＂, ＂ ＂, ＂!12345＂}     for _, tc := range testcases {         f.Add(tc) // Use f.Add to provide a seed corpus     }     f.Fuzz(func(t *testing.T, orig string) {         rev, err1 := Reverse(orig)         if err1 != nil {             return         }         doubleRev, err2 := Reverse(rev)         if err2 != nil {             return         }         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)         }     }) }