jacoco&mutation

jacoco: if the quantity of the unit test is enough.

mutation: if the quality of the unit test is good.

1. Jacoco

jacoco: cover those branches, all of the possible way to get to each line.

there are 8 branches for try with resource block. actually, there is only 6. hardly to cover them.

2. Mutation

https://www.baeldung.com/java-mutation-testing-with-pitest

mutation: if the boundary or condition has changed, the unit test should fail, killed. Or survived which means the unit test is not good.