Talk I gave at the Voxxed Days Bucharest 2017 conference.

1. Mutation Testing
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13. $327.6 million

25. really?

33. return a + b;

34. return a + b;

36. public class Calculator {
public int sum(int a, int b) {
return a + b;
}
}

37. @Test
public void
force100PercentCoverage() {
calculator.sum(0, 0);
}

44. return a + b;

45. return a - b;

48. ●

49. ●
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50. ●
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51. ●
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52. return a - b;

70. public class Calculator {
public int sum(int a, int b) {
return a + b;
}
}
@Test
public
void force100PercentCoverage() {
calculator.sum(0, 0);
}

71. > MathMutator
>> Generated 1 Killed 0 (0%)
> KILLED 0 SURVIVED 1
> TIMED_OUT 0 NON_VIABLE 0
> MEMORY_ERROR 0 NOT_STARTED 0
> STARTED 0 RUN_ERROR 0
> NO_COVERAGE 0

72. @Test public void
Should_ReturnSum_When_SummingTwoValues() {
// given
int a = 1;
int b = 2;
// when
int result = calculator.sum(a, b);
// then
assertThat(result).isEqualTo(3);
}

73. > MathMutator
>> Generated 1 Killed 1 (100%)
> KILLED 1 SURVIVED 0
> TIMED_OUT 0 NON_VIABLE 0
> MEMORY_ERROR 0 NOT_STARTED 0
> STARTED 0 RUN_ERROR 0
> NO_COVERAGE 0

76. ●
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82. if (a >= 100) {
throw new IllegalArgumentException();
}
if (a < 100) {
fooBar();
}

83. if (a >= 100) {
throw new IllegalArgumentException();
}
if (a < 100) {
fooBar();
}

87. return a + b;

88. return a + b;

89. return a + b;
return a - b
return 0

90. return a + b;
return a - b
return 0

91. :)

100. // given

101. // given
// when

102. // given
// when

106. Jenkins

116. Thank you
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