Code quality

IT1901 Fall 2021 - 10th Lecture

Code quality

Code quality

  • automated tests

  • coding standards and consistent formatting

  • check for higher level types of errors (bug patterns)

Automated tests

  • decrease the effort for running and re-running tests

  • there are several types metrics that can be used to measure test coverage

JaCoCo

  • Java Code Coverage (JaCoCo)

  • popular tool for measuring code coverage in Java projects

  • measures several metrics

JaCoCo metrics

  • Instructions

  • Branches (exception handling is excluded)

  • Cyclomatic Complexity - "According to McCabe1996 cyclomatic complexity is the minimum number of paths that can, in (linear) combination, generate all possible paths through a method."

  • Lines

  • Methods

  • Classes

https://www.jacoco.org/jacoco/trunk/doc/counters.html

Tools for automatic code checking

Checkstyle

  • static analysis

  • finds errors like

    • references to variables with undefined value

    • variables that are never used

    • syntax and coding standards violations

    • dead code blocks

Checkstyle (2)

  • naming conventions

  • line length

  • whitespace

  • Javadoc comments

  • annotations

Checkstyle (3)

  • can be configured to use a certain set of checks

  • extendable - one can write own checks

  • plugins for IDEs

Checkstyle examples

Spotbugs

  • checks bytecode and not the source

  • looks for "bug patterns"

  • example:

An apparent infinite loop (IL_INFINITE_LOOP)
This loop doesn't seem to have a way to terminate (other than by perhaps throwing an exception).

Spotbugs (2)

  • extendable

  • plugins for Maven Gradle Ant

  • Eclipse IDE integration

Spotbugs examples

Norwegian University of Science and Technology