Monthly Archives: September 2015

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 Pt2: Black-box testing: techniques for functional testing of software and systems

Chapter 1: Introduction

This chapter introduces testing purposes, roles, and methods.

The first thing that hits me are the definitions. Is this book like 20 years old or something? The Performance Bug and Security Bug definitions have grey hair. I like how Dr. Beizer dances around the unit, component, and integration tests. I can now understand it as well as I’ve ever understood it – but I won’t try explaining this to a child because they’ll tear me apart. People don’t try to break software anymore. They find where it’s already broken, it’s weaknesses, and it’s limitations. Otherwise, I generally agree with the definitions.

I agree with the numbered reasons for testing software. Most of these reasons can be incorporated into a cucumber scenario. The “penultimate objective” implies that using some kind of find-rate will help make a decision about readiness – I disagree because it could be a problem with the pesticide paradox.

In the Test Strategies section, test strategy is so much more than test techniques. I’m surprised to see them treated an synonyms. But there… BAM! Behavioral testing IS black box testing. I also like that the author doesn’t assume that unit tests are white box tests – one could test units and methods without knowing the code within them, only the promise of the interfaces.

I noticed that when the author talks about the progressive cost of testing units, to components, to integration, to system testing, he leaves out that the biggest cost of those bugs found late are because the time passed since the bug’s introduction is greater AND the number of people involved in repeating past work is higher (building, deploying, and possibly releasing).

In the testing isn’t everything section, I am wondering what happened to Formal Inspections. I’m fully trained in them, though I haven’t participated in one since probably 1997. I like how he says don’t try to justify automated tools as if that ever worked. I hate to do it but I have to do it.

The process section seems pretty old school as well. Old fashion we must have group discipline vs. current day we must have personal discipline. Or maybe I’m just remembering the command & control days poorly, and the short-cuts of today as not poorly enough.

I did not love this chapter. It’s basic and out of date. If I were to teach this chapter to younger testers/developers, I would focus on what has expired, and what replaced it. Then I would ask for reflections of what the students wish we had retained from the days this book was written.

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.