EclEmma/JaCoCo

EclEmma/JaCoCo
An Introduction

Prof. David Bernstein
James Madison University

Computer Science Department

bernstdh@jmu.edu

Motivation

Purpose of Testing:
- Identify faults (i.e. defects that could give rise to a failure)
An Observation:
- If a test do not cause a particular piece of code to be executed it can't possibly identify a fault in that piece of code

Motivation (cont.)

What Test Tools/Harnesses/Frameworks Provide:
- A way to write, organize, and run repeatable tests
What They Don't Provide:
- A way to identify what pieces of code are and aren't executed

Overview of EclEmma/JaCoCo

Purpose:
- Keep track of the statements and "branches" covered by a test (either using a test harness or a driver)
Output:
- A hierarchical coverage report
- A marked-up source file that indicates the coverage

A Note About Terminology

EclEmma/JaCoCo:
- The number of "branches" is the sum of the number of possible Boolean values in an expression
Common Usage:
- The number of "branches" is the number of edges in the execution graph (i.e., 2 for a Boolean expression, regardless of the number of sub-expressions, \(N\))
- The number of "conditions" is the sum of the number of Boolean values (i.e., \(2N\))
- The number of "multiple conditions" is the number of possible combinations (i.e., \(2^N\) in the worst case)

EclEmma/JaCoCo in an IDE

Launching:
- There is usually a button to run the tests using EclEmma (e.g., in Eclipse)
Coverage Report:
- The hierarchical coverage report is usually available in the IDE (e.g., in the "Coverage" tab if the Output View in Eclipse)
- It only show the instruction coverage (which is comparable to the statement coverage)

EclEmma/JaCoCo in an IDE (cont.)

Marked-Up Source:
- The source code is usually color-coded and marked-up in other ways
- You can usually hover the cursor over the marked-up source to get more information
- This information is far more valuable and important that the coverage report
Clearing the Mark-Up:
- There is usually a button that allows you to clear the mark-up from the source code (e.g., in Eclipse)

EclEmma/JaCoCo in an IDE (cont.)

Statement Mark-Up:
- The statement itself is color-coded (green is fully covered, yellow is partly covered, red is uncovered)
"Branch" Markup:
- A colored diamond is shown in the margin
Color Codes:
- Green indicates full coverage
- Yellow indicates partial coverage
- Red indicates no coverage