Tag Archives: modeling

Book Review Pt4: Black-box testing: techniques for functional testing of software and systems

Chapter 3: Control Flow Testing

This chapter introduces a basic graph, control flow. I found the tax documents for this exercise.

I read this in two parts. The first part, after the standard definitions section, focused on the relationships of a control-flow model, how they vary, and how to draw them. I liked the use of the truth table to show the relationships in a compound predicate.By the end of this section, I knew (remembered might be a better term) how to use the tactics of this technique. I could differentiate when the nodes would be serial instructions and when they would be selection as an if or case statement..

Dr. Beizer presented a step-by-step instruction set for building and using the control-flow model for testing. The model development seemed to be as if I were modeling a script or coded program. but showed what happened in the methods as well. The steps within the tax instructions gave that feel. The space of each instruction gave us a memory register to store the result. Each instruction did one thing… well, mostly. While I didn’t like the idea of reviewing 18 year old tax instructions, it worked well with this lesson.

The coverage, which is beginning to be developed in the previous chapter, starts to become more relevant. Where is the risk? In some places, the decisions seem somewhat arbitrary; to the whim of the author. Most of the coverage decisions are direct to the risks, and causes of the risks. Even within those, some of the reasons appear to be “old” ways of thinking.

In summary, this chapter gives the tester something they can use right now. It is the first finished feature of model-based testing. It is releasable, usable, and helpful.

Book Review Pt3: Black-box testing: techniques for functional testing of software and systems

Chapter 2: Graphs and Relations

This chapter introduces graphs as the central tool of testing.

Just running through the definitions got me pumped for testing. Every relationship Dr. Beizer described brought about examples in my head from software that I commonly test in my job. Then I saw the Question/Answer of the book. What do you do when you see a graph? Cover it! In 20 years, that has never left me or my test methodology.

I am not an expert on graphing so I did not see anything blatantly left out. I noticed in the undirected links section of definitions that the author didn’t think symmetric relations are not common in testing – I thought that modern software models include load balanced services, as well as multiple threads, which may have those relationships. I have tested those relationships many times.

Regarding the graph types used in testing, I took interest to the those. I felt that the transaction flow model he described doesn’t get enough attention. The finite-state model of menus… modern menus often change based on the current task or context – in the author’s word processing example, one may see a different menu set when editing a table.

While I enjoyed the discussion of transitive/intransitive relationships, I really liked the end. To paraphrase, If specification or programmer is confused about transitivity, then you have a fertile ground for testing.

The examples of the relationship types are helpful. Except the part about equivalence classes. I had to look at 3 web definitions and two YouTube videos before I felt comfortable. Then I reviewed a single partition example and said “oh yeah, I know that.”

The concept of the matrix of relationships between nodes was completely boring, but so much more efficient. If I were modeling with intention to automate coverage of a model, I would use the matrices in some form. But I get why Dr. Beizer says “…the format is cumbersome and error-prone for large matrices.”

The generic testing principles outlined have covered a great deal of my testing lifetime. It’s also the ToC for the rest of this chapter. Each instruction expands to a cookbook for creating a testing tool.

  1. Define the graph
  2. Define the relation
  3. Node Cover
  4. Link Cover
  5. Test All Weights
  6. Design Loop Tests

The instructions are simple, and mostly straight-forward. I didn’t particularly like calling properties as ‘weights’ because I think of weight as a particular type of property. Like the weight might show the likelihood one branch of the graph is used compared to an alternate branch. The author also describes the purpose & significance of each step.

I am not sure the ‘test all weights’ is necessary as a separate step. The properties can be tested within the node cover & link cover. They should be tested there.

In summary, I think this chapter sets up the following chapters by creating vocabulary and tools for them.

Book Review Pt1: Black-box testing: techniques for functional testing of software and systems

On the 20th anniversary of Black-box testing: techniques for functional testing of software and systems (1995) by Dr. Boris Beizer, the first book I ever read about… actually, the first thing I read about software testing, I review the book to introduce it to the generation of testers that never heard of it.

First, I have to admit that I forgot the premise of the book was to build knowledge about modeling in order to support development of software tools. I generated tests with a product in the late 90’s called TestMaster by Teradyne Software. Yes, I just linked to GeoCities. I also developed my own generator after being inspired by Harry Robinson’s Intelligent Test Automation.

The section about Missing Models explains this book in relation to software testing books from before this book’s existence, focusing mostly on Myers’ The Art of Software Testing. It describes different types of models including logic-based models and language-based models. Thanks for reminding me about how much I have not read.

Right after the preface, BAM! I see the readme.doc chapter. Now I know that I’m dealing with a softare professional, in the greatest sense of the word. Read this, it’s quick. The books is efficiently organized, so it’s to have a good map. The readme explains the structure of the chapters in relation to each other, and the structure of each chapter.

I am already excited about this.