Fuzz Testing in Dart

What is fuzz test.

Fuzz testing is a way detect unexcepted inputs for functions.
Create a folder for fuzz testing.
And put your files under this folder.

import ‘package:fuzz_dart/fuzz_dart.dart’ as fuzz_dart;

void main(List<String> arguments) {

}

Example.

This is greeter function.
We have a control here.
But we don’t have any constraint for substring. If name variable length less than 10 this function will throw error.
So fuzz testing finds bug like this. And generate html file.
Run this file dart run {FILENAME}

 void main(List<String> arguments) {
  greeter(String name, String lastname) {
    if (name.length > 13) {
      throw Exception('name is so long');
    }
    name.substring(10)
    return "hello $name $lastname";
  }

  fuzz_dart.Fuzzer greeterFunctionFuzzer = fuzz_dart.Fuzzer(
      type: [fuzz_dart.AcceptedTypes.string],
      iterateCount: 12,
      fileName: 'greeter-fuzzer');
  greeterFunctionFuzzer.iterate(greeter, 'greeting!',
      description: 'Returns name and lastname');
}

Output

    Exception: name is so long - Arguments: [ovfpdf|qelzyavu`, m}oqc~wgo]
RangeError (start): Invalid value: Not in inclusive range 0..2: 20 - Arguments: [g, du~klr]
Exception: name is so long - Arguments: [w{kpa}tdy}r~slrnvstp, s|_qr|rtsjzrz~vid}|dlvyvyi_~d~tbooj_|lvmq]
Exception: name is so long - Arguments: [ik|ca|k_gdilltbyyl|osooyzdirjza{{y, zuoo~u}woxsx|kqznyucvadwnpnmp_kp]
RangeError (start): Invalid value: Only valid value is 0: 20 - Arguments: [, fypr|cjnk|irec|vepfpypgs~rdjeltr_y{}io|{ucre`~d]
Exception: name is so long - Arguments: [vhedjuscuoervjauram`y}i{q{mxigw, sxypbkwjrqszjlszoy}siiswclhqdrpylwiprk]
Exception: name is so long - Arguments: [~ol{`butmq~how, jkfykl{i`spvoqz~qjkqcm`]
Exception: name is so long - Arguments: [~nmgrmmoujpqyssvgz{hjtm~_w, zqx{|tkhdpg]
Exception: name is so long - Arguments: [ylne}rmrwrear_fv~g`z{{dz_ecsefk|rot_bvfqa, ejwu]

Example 2

Make sure your parameter order is correct in type property.

 import 'package:fuzz_dart/fuzz_dart.dart' as fuzz_dart;

 String calculate(int num1, int num2) {
    if (num1 > 2000) {
      throw Exception('num1 should lower than 2000');
    }
    return "result of two number is ${num1 + num2}";
  }
  String calculate2(int num1, int num2, int num3) {
    return "result of three number is ${num1 + num2 + num3}";
  }

  fuzz_dart.Fuzzer greeterFunctionFuzzer = fuzz_dart.Fuzzer(
      type: [fuzz_dart.AcceptedTypes.string],
      iterateCount: 12,
      fileName: 'greeter-fuzzer');

  fuzz_dart.Fuzzer intFuzzer = fuzz_dart.Fuzzer(
      type: [fuzz_dart.AcceptedTypes.integer],
      iterateCount: 3,
      fileName: 'fuzzer 1');

  fuzz_dart.Fuzzer intFuzzer2 = fuzz_dart.Fuzzer(
      type: [fuzz_dart.AcceptedTypes.integer],
      iterateCount: 2,
      fileName: 'fuzzer-2');

 intFuzzer2.iterate(calculate, 'calculator 1');
  intFuzzer.iterate(calculate2, 'calculator 2');
  greeterFunctionFuzzer.iterate(greeter, 'greeting!',
      description: 'Returns name and lastname');
  listFuzzer.iterate(arrs, 'list fuzzer fun');
  cityFuzzer.iterate(city, 'city', description: 'Returns current index');