Sebastian Bergmann

For the upcoming PHPUnit 3.5, I have factored out all code that is related to code coverage and put it into a separate component: PHP_CodeCoverage.

PHP_CodeCoverage is a component that provides collection, processing, and rendering functionality for PHP code coverage information. It makes PHPUnit's mature code coverage functionality available outside of PHPUnit.

Having all code that deals with code coverage in a separate component allows for easier development and better testing. The first result of these improved development conditions is a small new feature that I recently implemented, the support for the CRAP metric.

From crap4j.org:

The CRAP (Change Risk Analysis and Predictions) software metric [has] a mildly offensive metric name [and helps] to help protect you from truly offensive code.

The CRAP metric combines cyclomatic complexity and code coverage from automated tests (e.g. [PHPUnit] tests) to help you identify code that might be particularly difficult to understand, test, or maintain — the kind of code that makes developers say: “This is crap!” or, if they are stuck maintaining it, “Oh, crap!”.

The screenshot below shows how the CRAP metric is reported in the HTML code coverage report:

The upcoming 3.2 release of PHPUnit adds a couple of software metrics to the data that is stored in PHPUnit's test database. Below is a list of the metrics that are calculated and collected:

• Project Level
  • Number of Interfaces (INTERFS)
  • Number of Abstract Classes (CLSa)
  • Number of Concrete Classes (CLSc)
  • Number of Classes (CLS)
  • Number of Root Classes (ROOTS)
  • Number of Leaf Classes (LEAFS)
  • Maximum Depth of Intheritance Tree (maxDIT)
• File Level
  • Lines of Code (LOC)
  • Comment Lines of Code (CLOC)
  • Non-Comment Lines of Code (NCLOC)
  • Lines of Executable Code (ELOC)
  • Lines of Executed Code
  • Code Coverage
• Function Level
  • Lines of Code (LOC)
  • Lines of Executable Code (ELOC)
  • Lines of Executed Code
  • Code Coverage
  • Cyclomatic Complexity
  • Change Risk Analysis and Predictions (CRAP) Index
• Class Level
  • Lines of Code (LOC)
  • Lines of Executable Code (ELOC)
  • Lines of Executed Code
  • Code Coverage
  • Attribute Inheritance Factor (AIF)
  • Attribute Hiding Factor (AHF)
  • Class Size (CSZ)
  • Class Interface Size (CIS)
  • Depth of Inheritance Tree (DIT)
  • Method Inheritance Factor (MIF)
  • Method Hiding Factor (MHF)
  • Number of Children (NOC)
  • Number of Interfaces Implemented (IMPL)
  • Number of Variables (VARS)
  • Number of Non-Private Variables (VARSnp)
  • Number of Variables (VARSi)
  • Polymorphism Factor (PF)
  • Weighted Methods per Class (WMC)
  • Weighted Non-Private Methods per Class (WMCnp)
  • Weighted Inherited Methods per Class (WMCi)
• Method Level
  • Lines of Code (LOC)
  • Lines of Executable Code (ELOC)
  • Lines of Executed Code
  • Code Coverage
  • Cyclomatic Complexity
  • Change Risk Analysis and Predictions (CRAP) Index

The example below shows how you can access, for instance, the Cyclomatic Complexity information for all methods of a project.