Videos Screenshots Introduction Maintainability Software Reuse Earlier Screenshots

Research conducted at the S.U. DOPL lab supervised by Dr. James W. Fawcett.

VERDICTS Live Video Capture

VERDICTS thread view demo showing quickly zooming into method call patterns.

1:33516x434 (window)(no audio)2.6 MiB MP4 video
Alternative:OGV, 4.3 MiB
Demonstrating how VERDICTS captures and shows method calls in a test program, CircleSurround.

3:161024x736 (screen)(with audio)5.4 MiB MP4 video
Alternative: OGV, 21.25 MiB

VERDICTS Screenshots

These screenshots can give you a quick overview of some of the most useful VERDICTS visualizations. Screenshots are followed by VERDICTS description, motivation (maintainability and software reuse) and earlier screenshots.

Apache Ant, detail
(dynamic analysis)

Apache Ant
(dynamic analysis)

(dynamic analysis)

VERDICTS analysis

Statistics for I/O values,
BoxPlot, Corr. Matrix

X-Y Plot
with Circle-Surround

Method contract and user-defined probe vars

Statistics with user-
defined probe vars

VERDICTS Analysis of Apache Ant, Detail

Detail from analysis of Apache Ant, showing method interaction patterns in VERDICTS style colored box-in-box views. Each big box is a method call, each box within it is a call made from that method call (to another method of interest). This is our novel visualization for method call interactions that reveal significant repeated patterns and changes in patterns of behavior. The image below shows how this view works.

VERDICTS Analysis of Apache Ant

VERDICTS visualization showing method call interactions in Apache Ant, using box-in-box views to reveal patterns of behavior. VERDICTS allows quickly zooming in and out to reveal smaller and larger patterns in this view.

VERDICTS Analysis of JUnit

VERDICTS visualization from analysis of JUnit, showing inter-method relationships using VERDICTS' own box-in-box views.


This diagram shows patterns of behavior visible in analysis of a portion of VERDICTS code base. Box-in-box views show caller-callee relationships as before.

VERDICTS Aggregate View: Statistics of Method Arguments

This VERDICTS view shows full range and habitual range of method call in/out values using boxplots, density gradient background, and outliers marked with tick marks. User-defined probe variables can be added. Nonvariables (std dev = 0) are highlighted in red. Correlation matrix: Darker boxes have higher correlation, negative correlation would be shown with red square around box. Clicking on any box brings up that X-Y plot. Nonvariables cause degenerate X-Y plots of vertical/horizontal line or single point, as highlighted in the correlation matrix view.

Box Plot & Distribution DensityCorrelation Matrix

VERDICTS X-Y Plot with Circle-Surround Visualization

Plots between two variables (method in/out variables and user-defined probe/contract variables) can be viewed as standard plots, or can be made to quickly reveal overlapping values by using a visual slider as shown here. Our novel Circle-Surround view compactly shows repeated values in a way that can be quickly grasped as well as hovered and clicked to reveal information about the corresponding method call. Here's an example of circle-surround view with 516 overlapping points (passing contracts) from VERDICTS analysis of a portion of the Apache Commons Collection:

VERDICTS Contract, User-Defined Probe Variables

A method contract is made up of in/out arguments for the method and user-defined probe variables with Java expression definitions as seen above (added without restarting target program). All variables (in, pre, $result, post) are tracked for statistical analysis using box-plots and correlation matrix, and can also be plotted against each other using X-Y plot. To create a method contract, any boolean variable can be asserted (blue target icon) to be always true.

VERDICTS Contract Statistics

Another statistics screenshot showing arguments, user-defined pre- and post-variables, box plots, range, and correlation matrix. Here, correlation matrix also has "=" icons, where two variables are always equal in value (in all method calls for this method). Boolean constant values in red (always 1.0 = True) are as we had expected. Negative correlations are shown with red box outline.

VERDICTS Introduction

Visual Exploratory Requirements Discovery and Injection
   for Comprehension and Testing of Software

VERDICTS is a technique and prototype tool to demonstrate a new approach to combining software comprehension and testing by visualization and incremental discovery and addition of requirements to existing software.

VERDICTS gathers live program execution data and interacts with the target program to help developers analyze the aggregate behavior by viewing, statistically analyzing, and testing multiple calls to each function traced. In our quantitative comparisons, using VERDICTS significantly speeds up analysis of patterns of behavior as compared to a modern IDE (Eclipse), mainly through box-in-box views of method call interactions and patterns. My full PhD thesis is available online here (262 pages).

Maintainability: Software That Satisfies Customers, But Frustrates Developers

Even when software performs to the satisfaction of many customers, it may have been developed with bad software engineering practices that produce unmaintainable (often incomprehensible) software.

Unfortunately this happens more often than we would like to admit, because cutting corners is efficient in the beginning, by skipping large-scale analysis, design and documentation and jumping straight into writing code. As there is no big-picture view of the system, new developers cannot easily comprehend software as a whole, due to:

For such software, a software comprehension and specification/feature discovery session may have to precede any type of maintenance task.

Software Reuse

Making a part of software reusable, ideally by compiling many related reusable functions into a library, requires much effort, especially to test these functions thoroughly to make them more generally applicable, as would be required of a reusable software component.

Opportunistic Software Reuse refers to reuse of parts of software that were not designed or documented for the purpose of reuse.

If you are working on an open-source project, you can reuse parts of other open source projects available on the internet, using public code search engines such as Koders and Google Code Search. For proprietary software development, you may have access to a large company code base, which may again be accessible through enterprise versions of code search engines.

As there is no universal specification language, these code search engines do text-search in source code, which often retrieves many false positive source code files.

Similar to exploratory testing ideas, VERDICTS allows exploratory discovery of how a software component operates. A VERDICTS session allows the developer to better understand the software component while generating a reusable specification for the component. Actually, evolving the specification is how the developer tests different ideas about the operation of the component. VERDICTS can generate unit tests based on the discovered specifications and trace data collected in the VERDICTS session. The unit tests (which contain specific component input data), and the more generally applicable specifications represent both human-readable documentation of component behavior as well as executable tests to verify component correctness.

Earlier Screenshots

Note: These screenshots are from an earlier version of VERDICTS. New version has more information-rich versions of these visualizations as well as new visualizations such as those on top of this page.

Contracts, User-Defined Observables

Pre-conditions and post-conditions for methods can be created and modified while the target program is running. These define method contract, what is expected from this method.

Interactive live contract-setting allows new paradigms. The contract may represent:

In the screenshot below, blue-black target icons represent contracts. Each line represents an observable, a user-defined variable within the context of the method call.

Tracing Session, Pass/Fail

For each tracing session, the user selects the methods to be traced, starts the session (starts recording), interacts with the target program (without having to ever stop the program), and stops the session. Then, all the method calls, their arguments (as well as return type and contract-specific user-defined observables), and whether they passed or failed the expectations set by the contracts can be viewed as seen here.

Aggregate Indicators: Statistics, Plots

Aggregate behavior of methods can be observed by looking at correlations between the observables (arguments, return type and user defined variables that are of primitive type) as well as plots between pairs of observables. The patterns observed suggest new contracts that can be declared either to tighten specifications or to create hypotheses to better understand actual program behavior.

This research was conducted at the Syracuse University DOPL lab supervised by Dr. James W. Fawcett.