Incorrect code coverage when switch with enum is involved

Answered

I always use "Run SomeTest with Code Coverage" and noticed today some weird results when the source code uses a switch statement with an enum.

 

The class to test:

public class Calculator {
public int calc(int op, int i1, int i2) {
switch (op) {
case 0:
return i1 * i2;
default:
throw new UnsupportedOperationException("Unknown operation " + op);
}
}
}

And the test class:

public class CalculatorTest {

private final Calculator calculator = new Calculator();
private final int i1 = 5;
private final int i2 = 7;

@Test
public void calc0() {
assertThat(calculator.calc(0, i1, i2)).isEqualTo(35);
}

@Test
public void calc1() {
assertThatThrownBy(() -> calculator.calc(1, i1, i2))
.isInstanceOf(UnsupportedOperationException.class);
}

}

If I run this class with code coverage, I get the expected result:

 

Now let's change Calculator class using an Operation enum:

public enum Operation {
ADD, SUBTRACT, MULTIPLY, DIVIDE
}
public class Calculator {
public int calc(Operation op, int i1, int i2) {
switch (op) {
case MULTIPLY:
return i1 * i2;
default:
throw new UnsupportedOperationException("Unknown operation " + op);
}
}
}

And the updated test class:

public class CalculatorTest {

private final Calculator calculator = new Calculator();
private final int i1 = 5;
private final int i2 = 7;

@Test
public void calc0() {
assertThat(calculator.calc(Operation.MULTIPLY, i1, i2)).isEqualTo(35);
}

@Test
public void calc1() {
assertThatThrownBy(() -> calculator.calc(Operation.ADD, i1, i2))
.isInstanceOf(UnsupportedOperationException.class);
}

}

But if I now run the test class, the test coverage report shows some strange results:

 

I tried both JaCoCo as IntelliJ code coverage runners with the same result.

5 comments
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Hello,

Please tell if the same issue is reproduced for you with the latest IntelliJ IDEA version? (https://www.jetbrains.com/idea/download/#section=mac)

Please also clarify what versions of frameworks are used.

Thank you 

0
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I am already using the latest version (Version: 2020.2.1 Build: 202.6948.69), no IDE or plugin updates available.

 

I created a new simple Java project with only 2 dependencies to write the test class (AssertJ & JUnit). And the results seem to be different from what I noticed yesterday: using IntelliJ code coverage runner gives the expected 100% code coverage when using enum in switch; but with JaCoCo code coverage runner I still get the strange code coverage reports (as mentioned in my previous post).

 

In the original (spring boot) project I notice exactly the same behavior as in the simple Java project. So ok with IntelliJ code coverage runner, but nok with JaCoCo one.

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hysterio,

If possible can you please share the sample project by attaching it to the issue created at YouTrack:

https://youtrack.jetbrains.com/

 

Or you may upload it here: http://uploads.services.jetbrains.com/

Thank you 

 

0
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Upload id: 2020_09_04_L1tfV3Wm5ZobxbsX (file: calculator.zip)

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Hello,

The issue looks like Jacoco specific. Please see the related discussion:

https://github.com/jacoco/jacoco/issues/660

Please contact the https://github.com/jacoco/jacoco

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