Tool Mentor:
Evaluating Code Coverage Using Rational PureCoverage
and Rational PurifyPlus (UNIX)
Purpose
This tool mentor provides an overview of how to use Rational PureCoverage to
quickly and easily identify the gaps in your testing.
PurifyPlus is a Rational product that includes PureCoverage
functionality.
To learn more about PureCoverage and for tutorial style introduction, read Installing
and Getting Started: Rational Purify, Rational PureCoverage, Rational Quantify.
For step-by-step instructions on using PureCoverage and for reference
information, see the PureCoverage online Help.
Related Rational Unified Process information:
Overview
PureCoverage collects a detailed set of coverage data for your program and
every component it uses. With this data, you can have confidence that the
program you're testing has been exercised—every line, every function—before you release it to your customers.
Tool Steps
To assess the
effectiveness of your code coverage and pinpoint the parts of your code that
are not exercised:
- Instrument and run a program using PureCoverage to collect coverage
data
- Use PureCoverage to analyze the
coverage data
- Run the program again to find coverage changes
1. Instrument and run a program using PureCoverage to collect
coverage data 
The first step in monitoring coverage is to collect the code-coverage data.
Just add the word purecov to the
beginning of your compile/link line. PureCoverage collects coverage
data at the function level and, if you compile with the -g
debugging option, at the line level. For example:
% purecov cc -g hello_world.c
PureCoverage makes a copy of your object code and libraries, and
instruments them using Object Code Insertion (OCI) technology to insert
instructions to detect which functions and lines are executed when you run the
program. When instrumentation is complete, run the instrumented program. For
example:
% a.out
As you exercise your code, PureCoverage records data about code
coverage.
You can call PureCoverage API functions from your program to take a
snapshot of the current data, enabling you to examine code coverage in stages.
When you exit the program, you can display the coverage data in the
PureCoverage Viewer by typing:
% purecov -view a.out.pcv
The PureCoverage Viewer summarizes coverage information for all
files and functions in your program, as well as detailed information for
individual files, functions, and lines, arranged hierarchically so you can
easily focus on the critical parts of your code.
Tip: In addition to using PureCoverage interactively, you can also
incorporate it into your test scripts for automated testing.
For more
information, look up the following topics in the PureCoverage online Help index:
- basic steps
- API functions
- report scripts
2. Use PureCoverage to analyze
the coverage data
The second step in monitoring coverage is to analyze the code-coverage data
that PureCoverage collected.
The PureCoverage Viewer provides information such as the number of
functions and the number of lines hit and missed by your tests. In addition, you
can see the percentage of functions and lines that were hit and the number of
times each function was called. You can also use the Annotated Source window to
further examine the program's code coverage, and to examine a specific
function's
coverage line-by-line.
To reduce the volume of coverage data you collect and display, and to improve
run-time, you can exclude files, or entire directories, when you instrument your
program.
Actual coverage data is the basis for PureCoverage's statistics and
annotated source display. However, there are occasions when it is more useful to
adjust the data to exclude specific lines, such as code that is logically
unavailable or is extremely difficult to reach. Using PureCoverage you can mark
code as dead code, tested code, and inspected code. This keeps the code from
being counted as unused code.
By default, PureCoverage merges the results of multiple runs of a
program so you can easily analyze the total coverage of the program over
multiple runs. You can also merge specific runs yourself or keep the coverage
data from multiple runs in separate files to analyze changes in coverage.
For more information, look up the following topics in the PureCoverage
online Help index:
3. Run the program again to find coverage changes
The third and final step in monitoring coverage is to rerun your tests to
see whether changes have caused the coverage to improve or regress.
After you make changes to your code, rerun the updated program with
PureCoverage and then use the PureCoverage pc_diff
report script to compare the new results to any previous run.
PureCoverage saves coverage data as a data file (.pcv) that you can
use for
further analysis or share with other PureCoverage users. You can save data to
an ASCII text file (.txt) to use outside of PureCoverage or you can format the
data on your own by using the provided report scripts.
To track your code coverage from release to release, archive your saved .pcv
files with your product releases.
Tip: If you have incorporated PureCoverage into your test scripts, you
can automatically save coverage data to a text file (.txt).
For more
information, see look up the following topics in the PureCoverage online Help
index:
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© 1987 - 2001 Rational Software Corporation
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Evaluating Code Coverage Using Rational PureCoverage and Rational PurifyPlus (UNIX)
