Testing
Everything having to do with testing: Unit testing, Integration Testing, Test Coverage
Test Coverage
It’s helpful to be able to measure how much of our code is covered by tests. This metric is known as “test coverage”
Line Versus Branch Coverage
Two common metrics are
- line coverage (how many lines of our code are covered by tests)
- branch coverage (how many branches, i.e. directions we can go, are covered by tests.)
It might be immediately obvious why those are not the same.
The answer is that not every if statement has an else.
color="blue";
if (x<10) {
color="red";
}
foo(color);
Suppose we have a test that covers the case where x<10 evaluates to true. Then for those code, we have 100% line coverage, but we
do not necessarily have 100% branch coverage unless we ALSO have a test that covers the case when x<10 evaluates to false. That means
that there is a branch into calling foo(color) when color still has the value “blue”, and that branch is untested.
Tools for measuring test coverage
One such tool is Jacoco (http://www.jacoco.org/jacoco/index.html)
The documentation for Jacoco can be difficult to follow.
Here is some help:
- https://www.codeproject.com/Articles/832744/Getting-Started-with-Code-Coverage-by-Jacoco
- http://www.baeldung.com/jacoco
- https://github.com/powermock/powermock/wiki/Code-coverage-with-JaCoCo
Related topics:
- Testing: Integration Testing with Maven—When you want to run the integration tests
- Testing: Jacoco Reports—How to interpret the reports (red, yellow, green)
- Testing: Jacoco via Maven—Setting up Jacoco test coverage, using Maven
- Testing: Spring Boot HTMLUnit—Testing Spring Boot Webapps