1.
Mutation Testing
ł

2.
$327.6 million

3.
really?

4.
return a + b;

5.
return a + b;

6.
public class Calculator {
public int sum(int a, int b) {
return a + b;
}
}

7.
@Test
public void
force100PercentCoverage() {
calculator.sum(0, 0);
}

8.
return a + b;

9.
return a - b;

10.
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11.
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12.
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13.
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14.
return a - b;

15.
public class Calculator {
public int sum(int a, int b) {
return a + b;
}
}
@Test
public
void force100PercentCoverage() {
calculator.sum(0, 0);
}

16.
> 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

17.
@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);
}

18.
> 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

19.
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20.
if (a >= 100) {
throw new IllegalArgumentException();
}
if (a < 100) {
fooBar();
}

21.
if (a >= 100) {
throw new IllegalArgumentException();
}
if (a < 100) {
fooBar();
}

22.
return a + b;

23.
return a + b;

24.
return a + b;
return a - b
return 0

25.
return a + b;
return a - b
return 0

26.
:)

27.
// given

28.
// given
// when

29.
// given
// when

30.
Jenkins

31.
Thank you
ł