The document discusses different approaches to testing the FizzBuzz problem using properties and traits. It describes testing FizzBuzz translations using NUnit tests, SpecFlow scenarios, and property-based testing with FsCheck. Examples are provided of generating test data to validate that numbers divisible by 3 return "Fizz", numbers divisible by 5 return "Buzz", and numbers divisible by 15 return "FizzBuzz". The document suggests creating a model to further demonstrate the robustness of the FizzBuzz solution.

1. T E S T I N G
T H E N E X T G E N E R AT I O N
M I K E H A R R I S

3. fscheck
specflow

4. is testing of
traits
specflow

5. is testing of
properties
fscheck

7. B E I N G

12. B E I N G

13. B E I N G
T H I N G S

14. B E I N G
T H I N G S
A S M A R T I N H E I D E G G E R
S P E A K S O F T H E M I N
“ T H E O R I G I N O F T H E
W O R K O F A R T "

15. I N T E R P R E TAT I O N S O F T H I N G S
• substances with properties or as bearers of traits
• sense perceptions
• formed stuff

16. S U B S TA N C E S W I T H P R O P E R T I E S
O R A S B E A R E R S O F T R A I T S

18. fscheck
specflow

19. is testing of
traits
specflow

20. is testing of
properties
fscheck

21. S U B S TA N C E S W I T H P R O P E R T I E S
O R A S B E A R E R S O F T R A I T S

23. Testing of Traits

24. is testing of
traits
specflow

26. I N E E D A
F I Z Z B U Z Z T R A N S L AT O R

27. C H E C K P O I N T
1 ) N O B M I ' D I V I S I B L E P O N G 3 F I Z Z J I C H E G H ' O H .
N O B M I ' D I V I S I B L E P O N G 5 B U Z Z J I C H E G H ' O H .
L AT L H S O ' M E H J I C H E G H ‘ O H .
!
2 ) ⎕ I O ← 0
( L , ' F I Z Z ' ' B U Z Z ' ' F I Z Z B U Z Z ' ) [ ¯ 1 +
( L × W = 0 ) + W ← ( 1 0 0 × ~ 0 = W ) + W ← ⊃ + / 1 2 × 0 = 3 5 |
⊂ L ← 1 + ⍳ 1 0 0 ]

28. S A M E PA G E !

29. C H E C K P O I N T
2 - > 2
3 - > F I Z Z
4 - > 4
5 - > B U Z Z
6 - > F I Z Z

30. M A K E I T S O .

32. F I Z Z B U Z Z

33. FizzBuzz(1 ) => “1”
FizzBuzz(2 ) => “2”
FizzBuzz(3 ) => “Fizz”
FizzBuzz(4 ) => “4”
FizzBuzz(5 ) => “Buzz”
FizzBuzz(6 ) => “Fizz”
…
FizzBuzz(15) => “FizzBuzz”

34. namespace FizzBuzz
{
public class FizzBuzzer
{
public string Translate(int value)
{
var result = string.Empty;
if (value % 3 == 0) result += "Fizz";
if (value % 5 == 0) result += "Buzz";
return string.IsNullOrEmpty(result) ? value.ToString() : result;
}
}
}

35. T E S T I N G T R A I T S

36. T H E N U N I T WAY

37. [TestCase( 2, Result = "2")]
[TestCase( 3, Result = "Fizz")]
[TestCase( 4, Result = "4")]
[TestCase( 5, Result = "Buzz")]
[TestCase( 6, Result = "Fizz")]
[TestCase(10, Result = "Buzz")]
[TestCase(15, Result = "FizzBuzz")]
[TestCase(45, Result = "FizzBuzz")]
public string FizzBuzz_Tests(int value)
{
return fizzbuzzer.Translate(value);
}

38. S P E C F L O W WAY

39. Feature: FizzBuzzerSpec
In order to be able to communicate with the
FizzBuzzons
As a Starfleet Captain
I want to be able to translate numbers to their
FizzBuzz value

40. Scenario: 2 must translate to the string 2
Given a FizzBuzzer
And the value of '2'
When translate is invoked
Then the result should be '2'

41. Scenario: 3 must translate to the string Fizz
Given a FizzBuzzer
And the value of '3'
When translate is invoked
Then the result should be 'Fizz'

42. Scenario: 5 must translate to the string Buzz
Given a FizzBuzzer
And the value of '5'
When translate is invoked
Then the result should be 'Buzz'

43. Scenario: 15 must translate to the string FizzBuzz
Given a FizzBuzzer
And the value of '15'
When translate is invoked
Then the result should be 'FizzBuzz'

44. Feature: FizzBuzzerSpec
In order to be able to communicate with the FizzBuzzons
As a Starfleet Captain
I want to be able to translate numbers to their FizzBuzz value
Scenario: 2 must translate to the string 2
Given a FizzBuzzer
And the value of '2'
When translate is invoked
Then the result should be '2'
Scenario: 3 must translate to the string Fizz
Given a FizzBuzzer
And the value of '3'
When translate is invoked
Then the result should be 'Fizz'
Scenario: 5 must translate to the string Buzz
Given a FizzBuzzer
And the value of '5'
When translate is invoked
Then the result should be 'Buzz'
Scenario: 15 must translate to the string FizzBuzz
Given a FizzBuzzer
And the value of '15'
When translate is invoked
Then the result should be 'FizzBuzz'

46. Feature: FizzBuzzerSpec
In order to be able to communicate with the
FizzBuzzons
As a Starfleet Captain
I want to be able to translate numbers to their
FizzBuzz value

47. Scenario: 2 must translate to the string 2
Given a FizzBuzzer
And the value of '2'
When translate is invoked
Then the result should be '2'

48. using FizzBuzz;
using TechTalk.SpecFlow;
using NUnit.Framework;
namespace FizzBuzzSpec
{
[Binding]
public class FizzBuzzerSpecSteps
{
[Given(@"a FizzBuzzer")]
public void GivenAFizzBuzzer()
{
ScenarioContext.Current.Add("FizzBuzzer", new FizzBuzzer());
}
[Given(@"the value of '(.*)'")]
public void GivenTheValueOf(int value)
{
ScenarioContext.Current.Add("value", value);
}
[When(@"translate is invoked")]
public void WhenTranslateIsInvoked()
{
var fizzbuzzer = ScenarioContext.Current.Get<FizzBuzzer>("FizzBuzzer");
var value = ScenarioContext.Current.Get<int>("value");
ScenarioContext.Current.Add("actual", fizzbuzzer.Translate(value));
}
[Then(@"the result should be '(.*)'")]
public void ThenTheResultShouldBe(string expected)
{
var actual = ScenarioContext.Current.Get<string>("actual");
Assert.That(expected, Is.EqualTo(actual));
}
}
}

49. Given a FizzBuzzer
!
[Given(@"a FizzBuzzer")]
public void GivenAFizzBuzzer()
{
ScenarioContext.Current.Add(
"FizzBuzzer", new FizzBuzzer());
}

50. And the value of '2'
!
[Given(@"the value of '(.*)'")]
public void GivenTheValueOf(int value)
{
ScenarioContext.Current.Add("value", value);
}

51. When translate is invoked
[When(@"translate is invoked")]
public void WhenTranslateIsInvoked()
{
var fizzbuzzer = ScenarioContext
.Current.Get<FizzBuzzer>("FizzBuzzer");
var value = ScenarioContext
.Current.Get<int>("value");
ScenarioContext
.Current.Add(
"actual", fizzbuzzer.Translate(value));
}

52. Then the result should be '2'
[Then(@"the result should be '(.*)'")]
public void ThenTheResultShouldBe(
string expected)
{
var actual = ScenarioContext
.Current.Get<string>("actual");
Assert.That(expected, Is.EqualTo(actual));
}

53. Scenario: 2 must translate to the string 2
Given a FizzBuzzer
And the value of '2'
When translate is invoked
Then the result should be '2'

54. Scenario: 5 must translate to the string Buzz
Given a FizzBuzzer
And the value of '5'
When translate is invoked
Then the result should be 'Buzz'

55. Given a FizzBuzzer
!
[Given(@"a FizzBuzzer")]
public void GivenAFizzBuzzer()
{
ScenarioContext.Current.Add(
"FizzBuzzer", new FizzBuzzer());
}

56. And the value of '5'
!
[Given(@"the value of '(.*)'")]
public void GivenTheValueOf(int value)
{
ScenarioContext.Current.Add("value", value);
}

57. When translate is invoked
[When(@"translate is invoked")]
public void WhenTranslateIsInvoked()
{
var fizzbuzzer = ScenarioContext
.Current.Get<FizzBuzzer>("FizzBuzzer");
var value = ScenarioContext
.Current.Get<int>("value");
ScenarioContext
.Current.Add(
"actual", fizzbuzzer.Translate(value));
}

58. Then the result should be 'Buzz'
[Then(@"the result should be '(.*)'")]
public void ThenTheResultShouldBe(
string expected)
{
var actual = ScenarioContext
.Current.Get<string>("actual");
Assert.That(expected, Is.EqualTo(actual));
}

62. Scenario: 2 must translate to the string 2
Given a FizzBuzzer
And the value of '2'
When translate is invoked
Then the result should be '2'

63. [NUnit.Framework.TestAttribute()]
[NUnit.Framework.DescriptionAttribute("2 must translate to the string 2")]
public virtual void _2MustTranslateToTheString2()
{
TechTalk.SpecFlow.ScenarioInfo scenarioInfo = new TechTalk.SpecFlow.ScenarioInfo(
"2 must translate to the string 2", ((string[])(null)));
#line 6
this.ScenarioSetup(scenarioInfo);
#line 7
testRunner.Given("a FizzBuzzer", ((string)(null)), ((TechTalk.SpecFlow.Table)(null)), "Given ");
#line 8
testRunner.And("the value of '2'", ((string)(null)), ((TechTalk.SpecFlow.Table)(null)), "And ");
#line 9
testRunner.When("translate is invoked", ((string)(null)), ((TechTalk.SpecFlow.Table)(null)), "When ");
#line 10
testRunner.Then("the result should be '2'", ((string)(null)), ((TechTalk.SpecFlow.Table)(null)), "Then ");
#line hidden
this.ScenarioCleanup();
}

64. G O O D , B U T N O T G R E AT.

66. Examples:
| value | expected value |
| 2 | 2 |
| 4 | 4 |
| 3 | Fizz |
| 9 | Fizz |
| 5 | Buzz |
| 25 | Buzz |
| 15 | FizzBuzz |
| 30 | FizzBuzz |

67. Scenario Outline: FizzBuzz translation
Given a FizzBuzzer
And the value of '<value>'
When translate is invoked
Then the result should be '<expected value>'
Examples:
| value | expected value |
| 2 | 2 |
| 4 | 4 |
| 3 | Fizz |
| 9 | Fizz |
| 5 | Buzz |
| 25 | Buzz |
| 15 | FizzBuzz |
| 30 | FizzBuzz |

68. [Given(@"a FizzBuzzer")]
public void GivenAFizzBuzzer()
{
ScenarioContext.Current.Add(
"FizzBuzzer", new FizzBuzzer());
}

69. [Given(@"the value of '(.*)'")]
public void GivenTheValueOf(int value)
{
ScenarioContext.Current.Add("value", value);
}

70. [When(@"translate is invoked")]
public void WhenTranslateIsInvoked()
{
var fizzbuzzer = ScenarioContext
.Current.Get<FizzBuzzer>("FizzBuzzer");
var value = ScenarioContext
.Current.Get<int>("value");
ScenarioContext
.Current.Add(
"actual", fizzbuzzer.Translate(value));
}

71. [Then(@"the result should be '(.*)'")]
public void ThenTheResultShouldBe(
string expected)
{
var actual = ScenarioContext
.Current.Get<string>("actual");
Assert.That(expected, Is.EqualTo(actual));
}

72. Examples:
| value | expected value |
| 2 | 2 |
| 4 | 4 |
| 3 | Fizz |
| 9 | Fizz |
| 5 | Buzz |
| 25 | Buzz |
| 15 | FizzBuzz |
| 30 | FizzBuzz |

73. [TestCase( 2, Result = "2")]
[TestCase( 3, Result = "Fizz")]
[TestCase( 4, Result = "4")]
[TestCase( 5, Result = "Buzz")]
[TestCase( 6, Result = "Fizz")]
[TestCase(10, Result = "Buzz")]
[TestCase(15, Result = "FizzBuzz")]
[TestCase(45, Result = "FizzBuzz")]
public string FizzBuzz_Tests(int value)
{
return fizzbuzzer.Translate(value);
}

74. Examples:
| value | expected value |
| 2 | 2 |
| 4 | 4 |
| 3 | Fizz |
| 9 | Fizz |
| 5 | Buzz |
| 25 | Buzz |
| 15 | FizzBuzz |
| 30 | FizzBuzz |

75. G R E AT.

82. "FizzBuzzSpecFizzBuzzSpecFizzBuzzerSpecFeature
_15MustTranslateToTheStringFizzBuzz","Passed","00:00:00.183","(loc
al)"
Given a FizzBuzzer
-> done: FizzBuzzerSpecSteps.GivenAFizzBuzzer() (0.0s)
And the value of '15'
-> done: FizzBuzzerSpecSteps.GivenTheValueOf(15) (0.0s)
When translate is invoked
-> done: FizzBuzzerSpecSteps.WhenTranslateIsInvoked() (0.0s)
Then the result should be 'FizzBuzz'
-> done: FizzBuzzerSpecSteps.ThenTheResultShouldBe("FizzBuzz")
(0.0s)

88. D O E S T H I S R E A L LY W O R K ? ! ?

89. W E C O U L D H AV E T H E
S Y S T E M G E N E R AT E D ATA F O R U S
T O I L L U S T R AT E T H E A D H E R E N C E O F P R O P E R T I E S

90. M A K E I T S O .

92. Testing of Properties

93. is testing of
properties
fscheck

94. T E S T I N G P R O P E R T I E S

95. T H E N U N I T WAY

96. [Test]
public void Divisible_By_3_Is_Fizz(
[Range(3, 300, 3)] int value)
{
var removeBuzz = (value % 5 == 0) ? 3 : value;
Assert.That(FizzBuzz(removeBuzz), Is.EqualTo("Fizz"));
}

97. [Test]
public void Divisible_By_5_Is_Buzz(
[Random(1, 10000, 100)] int value)
{
var removeFizz = (value % 3 == 0) ? 5 : value * 5;
Assert.That(FizzBuzz(removeFizz), Is.EqualTo("Buzz"));
}

98. F S C H E C K WAY

99. [TestCase]
public void Number_Divisible_By_3_Will_Return_Fizz()
{
Spec.ForAny<int>(value =>
_fizzBuzzer.Translate(value).Equals("Fizz"))
.When(value => value % 3 == 0 && value % 5 != 0)
.QuickCheckThrowOnFailure();
}

100. Ok, passed 100 tests.

101. [TestCase]
public void Number_Divisible_By_5_Will_Return_Buzz()
{
Spec.ForAny<int>(value =>
_fizzBuzzer.Translate(value).Equals("Buzz"))
.When(value => value % 3 != 0 && value % 5 == 0)
.QuickCheckThrowOnFailure();
}

102. Ok, passed 100 tests.

103. [TestCase]
public void Number_Divisible_By_15_Returns_FizzBuzz()
{
Spec.ForAny<int>(value =>
_fizzBuzzer.Translate(value).Equals("FizzBuzz"))
.Or(value => value % 15 != 0)
.QuickCheckThrowOnFailure();
}

104. Ok, passed 100 tests.

105. H M M M M

106. W E C O U L D C R E AT E A
M O D E L T O D E M O N S T R AT E T H E
R O B U S T N E S S O F T H E S O L U T I O N

107. M A K E I T S O .

108. T E S T I N G A G A I N S T
A M O D E L

109. F S C H E C K WAY

110. class FizzBuzzModel
{
public static string Translate(int value)
{
if (value % 15 == 0) return "FizzBuzz";
if (value % 3 == 0) return "Fizz";
if (value % 5 == 0) return "Buzz";
return value.ToString(CultureInfo.InvariantCulture);
}
}
[TestCase]
public void Will_Match_Model()
{
Spec.ForAny<int>(value =>
FizzBuzzModel.Translate(value).Equals(_fizzBuzzer.Translate(value)))
.QuickCheckThrowOnFailure();
}

111. class FizzBuzzModel
{
public static string Translate(int value)
{
if (value % 15 == 0) return "FizzBuzz";
if (value % 3 == 0) return "Fizz";
if (value % 5 == 0) return "Buzz";
return value.ToString(CultureInfo.InvariantCulture);
}
}

112. [TestCase]
public void Will_Match_Model()
{
Spec.ForAny<int>(value =>
FizzBuzzModel.Translate(value)
.Equals(_fizzBuzzer.Translate(value)))
.QuickCheckThrowOnFailure();
}

113. Ok, passed 100 tests.

114. H M M M M

115. W E C O U L D U S E A
S Y S T E M T O G E N E R AT E
D E G E N E R AT I V E T E S T D ATA
T O D I S P L AY C O R R E C T N E S S

116. M A K E I T S O .

117. T E S T I N G N E G AT I O N

118. F S C H E C K WAY

119. [TestCase]
public void Numbers_Not_Divisible_By_3_Do_Not_Fizz()
{
var noThrees =
from number in Any.OfType<int>()
where number%3 != 0
select number;
Spec.For(noThrees, x => _fizzBuzzer.Translate(x)
.Contains("Fizz") == false)
.QuickCheckThrowOnFailure();
}

120. Ok, passed 100 tests.

121. [TestCase]
public void Numbers_Not_Divisible_By_5_Do_Not_Buzz()
{
var noFives =
from number in Any.OfType<int>()
where number%5 != 0
select number;
Spec.For(noFives, x => _fizzBuzzer.Translate(x)
.Contains("Buzz") == false)
.QuickCheckThrowOnFailure();
}

122. Ok, passed 100 tests.

123. H M M M M

124. [TestCase]
public void Numbers_Divisible_By_15_Must_FizzBuzz()
{
var onlyFifteens =
from number in Any.OfType<int>()
where number%15 == 0
select number;
Spec.For(onlyFifteens, x => _fizzBuzzer.Translate(x)
.Equals("FizzBuzz"))
.QuickCheckThrowOnFailure();
}

125. Ok, passed 100 tests.

126. H M M M M

127. [TestCase]
public void Classify_Values()
{
Spec.ForAny<int>(x => true)
.Classify(
x => _fizzBuzzer.Translate(x).Equals("Fizz"), "Fizz")
.Classify(
x => _fizzBuzzer.Translate(x).Equals("Buzz"), "Buzz")
.Classify(x =>
_fizzBuzzer.Translate(x).Equals("FizzBuzz"), "FizzBuzz")
.Classify(x =>
_fizzBuzzer.Translate(x) != string.Empty, "Other")
.QuickCheckThrowOnFailure();
}

128. Ok, passed 100 tests.
55% Other.
22% Fizz, Other.
13% FizzBuzz, Other.
9% Buzz, Other.

129. H M M M M

130. [TestCase]
public void Collect_Values_For_Negatives()
{
Spec.ForAny<int>(x => true)
.When(x => x < 0)
.Collect(x => _fizzBuzzer.Translate(x))
.QuickCheckThrowOnFailure();
}

131. Ok, passed 100 tests.

132. G R E AT !

139. http://www.specflow.org/
specflow

140. https://github.com/fsharp/FsCheck
fscheck

142. T H A N K Y O U

143. M I K E H A R R I S
@ M I K E M K H
H T T P : / / C O M P - P H I L . B L O G S P O T. C O M /