Tool Mentor: Using Rational Visual PureCoverageTM to assess code coverage and test effectiveness
Purpose
This tool guide provides an overview of how to use Visual PureCoverage to quickly and easily identify the gaps in your testing of Visual C/C++, Visual Basic, and Java programs. To learn more about Visual PureCoverage, including how to filter coverage data, merge runs, and fine-tune data collection, read Getting Ahead with Visual PureCoverage. For step-by-step information about using Visual PureCoverage, see the Visual PureCoverage online Help.
Related Rational Unified Process activity: section "Execute Unit Test" in Activity: Perform Unit Tests.
Overview
This Tool Mentor is applicable when running Windows NT 4.0.
Visual 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, procedure, or method — before you release it to your customers. To assess the effectiveness of your code coverage, and pinpoint the parts of your code that are not exercised:
To assess the effectiveness of your code coverage:
1. Run a program using Visual PureCoverage to collect
coverage data 
The first step in monitoring coverage is to collect the code-coverage data.
For Visual C++, instrument and run the program, either directly from Microsoft Developer Studio using the Visual PureCoverage integration, or from Visual PureCoverage. During instrumentation, Visual PureCoverage makes copies of the executable and its associated modules. Visual PureCoverage also inserts additional code to detect which functions and lines were executed in the program. Visual PureCoverage shows you its progress as it instruments files.
For Visual Basic, run Visual Basic projects or p-code programs (Visual Basic 6.0 only), or Visual Basic native-code programs (Visual Basic 5.0 or later), either directly from Microsoft Visual Basic using the Visual PureCoverage integration, or from Visual PureCoverage. When you monitor projects or p-code programs, Visual PureCoverage puts the Visual Basic for Applications (VBA) interpreter engine into a special mode that enables Visual PureCoverage to monitor the engine’s operation and directly collect coverage data as your code runs. For native-code programs, Visual PureCoverage instruments the program and then collects code-coverage data. During instrumentation, Visual PureCoverage makes copies of the executable and its associated object libraries. Visual PureCoverage also inserts additional code to detect which procedures and lines were
executed in the program. Visual PureCoverage shows you its progress as it instruments files.For Java, run Java applets, class files, or code launched by container programs from Visual PureCoverage (using the Run Program dialog) or from the command line. When you monitor Java code, Visual PureCoverage puts the Microsoft virtual machine (VM) for Java into a special mode that enables Visual PureCoverage to monitor the VM’s operation and directly collect code-coverage data as the applet, class file, or code runs.
When Visual PureCoverage starts monitoring, it displays the Run Summary window so you can see both numerical and graphical information reflecting the progress of your testing, and check other information about the run. As you exercise your code, Visual PureCoverage records data about it’s code coverage. You can pause and resume data recording at any time, enabling you to check specific portions of code. You can also take a snapshot of the current data, enabling you to examine code coverage in stages.
When you exit the program, Visual PureCoverage displays the coverage data it collected. Because there can be a lot of data, Visual PureCoverage automatically filters out non-critical data from system libraries and other modules before it displays the program’s coverage details. As you analyze the coverage data, you can display more or less data.
Tip: In addition to using Visual PureCoverage interactively, you can also incorporate Visual PureCoverage into your test scripts for automated testing. For more information, look up scripts in the Visual PureCoverage online Help index.
More information? Look up developer studio, visual C++, visual basic, java, run summary, snapshots, and filters in the Visual PureCoverage online Help index.
2.
Using Visual PureCoverage's windows and tools to analyze the coverage data
The second step in monitoring coverage is to analyze the code-coverage data that Visual PureCoverage collected.
When you exit the program for which Visual PureCoverage has been collecting data, Visual PureCoverage displays the Coverage Browser window, displaying information such as the number of functions, procedures, or methods (collectively referred to here as functions) hit and missed by your tests, and the number of lines hit and missed by your tests. In addition, you can see the percentage of functions and lines hit, and the number of times each function was called.
You can use Visual PureCoverage’s other windows to further examine the program’s code coverage. To review coverage data for all functions in the current run, and to sort them by various criteria, use the Function List window. If debug line information is available, and you monitored functions at line level, you can use the Annotated Source window to analyze a specific function’s coverage line by line. Line-by-line coverage data is not available when you monitor a Visual Basic 6.0 p-code program. For the most detailed coverage data, monitor your Visual Basic 6.0 project directly from within Visual Basic 6.0 using the Visual PureCoverage integration.
Visual PureCoverage provides several ways to display only the data you’re interested in. For example, you can filter out data by module name, source file name, or function name. Visual PureCoverage automatically filters out non-critical data from system libraries and other modules before it displays the program’s coverage details. As you analyze the coverage data, you can display more or less data. You can also use the Show/Hide Columns dialog to display only the information you are currently interested in.
By default, Visual PureCoverage creates an Auto Merge entry in the Navigator window, so you can easily analyze the total coverage of the program over multiple runs. You can also merge specific runs yourself, to analyze coverage.
More information? Look up coverage browser window, function list window, annotated source window, filters, merging runs, and debug data in the Visual PureCoverage online Help index.
3. Run the program again and use Visual PureCoverage's
windows and tools 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.
Use the Navigator window to keep track of all the runs you’re working with. You can save coverage data as a Visual PureCoverage data file (.cfy), to use for further analysis or to share with other Visual PureCoverage users. You can save data to a tab-delimited ASCII text file (.txt) to use outside of Visual PureCoverage, for example, in test scripts or in Microsoft Excel. You can also copy data from the Coverage Browser window to use in a text editor or from the Function List window to perform further analysis in Excel.
To track your code coverage from release to release, archive your saved .cfy files with your product releases.
Tip: If you have incorporated Visual PureCoverage into your test scripts, you can automatically save coverage data to a text file (.txt). For more information, look up scripts in the Visual PureCoverage online Help.
More information? Look up navigator window and saving data in the Visual PureCoverage online Help index.
