Testing Generally

I sometimes consciously split the functionality I'm testing into two parts: general: behaviour that is the same, or similar, regardless of where it appears, how it is invoked and so on; and specific: which differs according to function, context, time, data types etc.

I'll tend to do this more on larger projects when the areas are new to me, or to the product, or if they're complex, or I think the test framework will be complex, or the specific is heavily dependent for its delivery on the general, or perhaps when the specific details are certain to change but the general will be stable.

I'll be looking to implement automation that concentrates first on general functionality and self-consistency and that will serve as a backstop when I move on to the more specific material.

To speed things up, to get wider coverage easily, and to avoid dependencies, I'll try to avoid crafting new test data by looking for data already in the company that can be reused. Static dumps from live servers can be good, but dynamically changing internal landfill instances are gold dust because they'll be running the latest Dev build and generating new data all the time.

Take the example of a server which exposes an API using HTTP. The API gives clients access to resources (by URLs) and actions on those resources (e.g. searching across back-end data sources). My functionality breakdown might include the following:

general: each resource is exposed to a client as custom data structures but some properties will be shared across resources, e.g. "children" always represents sub-resources whose URL can be derived from the resource itself.

An interesting subset of general functionality is those based on standards. In this case, the HTTP standard for client-server communications is well-defined and independent of your product (although your product may only implement parts of it and there are areas in which there is leeway for client and server to choose an action).

specific: any functions on the resources that are outside of HTTP are specific. For example, the query parameters on URLs will have a specific meaning to this server.

So how might I set up general testing, using pre-existing data here?

There's a huge space of potential tests to do with conformance to HTTP RFCs. As these tests are, for the most part, independent of the data in your system you can implement them without worrying about what data you have (if you request a resource that's not there, the system should respond with a 404).

A particular general test might request the children of a collection resource (effectively a folder) and then request each of them in turn. If they all exist, it confirms a degree of consistency between the back-end data, its presentation in the API, and the client-side view of it. Conversely, requesting a resource that you know should not exist (e.g. http://myserver/collection/thiswasnotachild) can confirm error behaviour. Note that you can not confirm that all of the children that should be there are present this way, without extra knowledge of whatever backs the server.

A subclass of specific tests is close to general: system meta data. That is, a set of attributes of the product that are true regardless of the data that's in the system. In the server example, perhaps there is a finite set of resource types that the server will enumerate. You can cheaply check that the server's list agrees with a list in your test suite without knowing what data is stored for any of those types.

If there is a lot of data in your test systems, randomising access to it lets you trade run-time of a given invocation of the suite against cumulative coverage over time, because different sets of data will be visited on each run. You can implement a cache of what's been touched in recent runs and avoid it later although I have found this not worth the hassle. On a landfill server, data can change under your feet which adds another dimension to the testing. And note that it can be productive to run the suite against servers without any data in their back-end stores at all.

These kinds of suites can also be parameterised. For example, we could ask the randomisation to run tests for a certain period of time, to a certain depth or breadth, for a certain number of data items or some other limit or search strategy. In an automated GUI test suite we're building at the moment, we're playing with parameters representing user behaviours such as "fast" vs "slow", "keyboard" vs "mouse" and so on for different invocations of the suite - running the same tests in different ways.

So why might this kind of testing be interesting?

It puts you in the product (or in the technologies on which the product depends) immediately, learning about both, getting background for the specific testing and testing to a level that is practical and sensible at any given time.

You quickly flesh out the basic structure of your test harness, learn what kinds of utility functions you'll need and the like. This can be invaluable when you're ready to extend to specific tests because you've got the infrastructure in place already. I try to partition the two sets of tests so that I can run them separately.

You end up testing against all sorts of malformed data (intermediate formats; buggy data, crafted data from the dev team, antique data from previous releases...) and learn a lot about how the application copes with them.

Consistency is a testing watchword (see e.g. FEW HICCUPPS) and time spent understanding the baseline level of consistency of a feature or product is seldom wasted.General testing is a lot about consistency.

When you're ready to, and if it makes sense to, you can extend to creating data as well. If I do this, I make a point of cleaning up test suite data at close.

It's clear that this approach has limitations. In particular, although it's data-driven, it's driven by the data that is present and by a one-sided view of that data. If it passes, it will tell you that no inconsistencies were found in the data and functionality touched by a particular run, but no more.

Despite this, it can be very productive and later become a regression test that extends as the data you point it at evolves. There's usually suitable data lying in your dev and test environments that belongs to you, was otherwise redundant and that you can get the extra value from.
Image: http://flic.kr/p/55ryMX

Comments

Unknown said…

So would it be fair to say that for you, "specific" means cases which verify specific data (or a known set of data) whereas "general" means cases which don't rely on any specific data, for which any data set could be used? (Or which are good for verifying large and varied data sets.)

October 15, 2013 at 10:40 AM

James Thomas said…

@Jenny: Pretty much. I don't think I'd phrase it as "verifying data", though. I think of it more as executing sets of checks against the software may or may not have specific dependencies, although they are primarily data dependencies in this example. Other dependencies might include configuration options, user accounts, server-side plug-ins, additional licensed features etc.

October 16, 2013 at 6:59 AM

Meet Me Halfway?

The Association for Software Testing is crowd-sourcing a book, Navigating the World as a Context-Driven Tester , which aims to provide responses to common questions and statements about testing from a context-driven perspective . It's being edited by Lee Hawkins who is posing questions on Twitter , LinkedIn , Mastodon , Slack , and the AST mailing list and then collating the replies, focusing on practice over theory. I've decided to contribute by answering briefly, and without a lot of editing or crafting, by imagining that I'm speaking to someone in software development who's acting in good faith, cares about their work and mine, but doesn't have much visibility of what testing can be. Perhaps you'd like to join me? --00-- "Stop answering my questions with questions." Sure, I can do that. In return, please stop asking me questions so open to interpretation that any answ...

Can Code, Can't Code, Is Useful

The Association for Software Testing is crowd-sourcing a book, Navigating the World as a Context-Driven Tester , which aims to provide responses to common questions and statements about testing from a context-driven perspective . It's being edited by Lee Hawkins who is posing questions on Twitter , LinkedIn , Mastodon , Slack , and the AST mailing list and then collating the replies, focusing on practice over theory. I've decided to contribute by answering briefly, and without a lot of editing or crafting, by imagining that I'm speaking to someone in software development who's acting in good faith, cares about their work and mine, but doesn't have much visibility of what testing can be. Perhaps you'd like to join me? --00-- "If testers can’t code, they’re of no use to us" My first reaction is to wonder what you expect from your testers. I am immediately interested ...

The Best Programmer Dan Knows

I was pairing with my friend Vernon at work last week, on a tool I've been developing. He was smiling broadly as I talked him through what I'd done because we've been here before. The tool facilitates a task that's time-consuming, inefficient, error-prone, tiresome, and important to get right. Vern knows that those kinds of factors trigger me to change or build something, and that's why he was struggling not to laugh out loud. He held himself together and asked a bunch of sensible questions about the need, the desired outcome, and the approach I'd taken. Then he mentioned a talk by Daniel Terhorst-North, called The Best Programmer I Know, and said that much of it paralleled what he sees me doing. It was my turn to laugh then, because I am not a good programmer, and I thought he knew that already. What I do accept, though, is that I am focussed on the value that programs can give, and getting some of that value as early as possible. He sent me a link to the ta...

Beginning Sketchnoting

In September 2017 I attended Ian Johnson 's visual note-taking workshop at DDD East Anglia . For the rest of the day I made sketchnotes, including during Karo Stoltzenburg 's talk on exploratory testing for developers (sketch below), and since then I've been doing it on a regular basis. Karo recently asked whether I'd do a Team Eating (the Linguamatics brown bag lunch thing) on sketchnoting. I did, and this post captures some of what I said. Beginning sketchnoting, then. There's two sides to that: I still regard myself as a beginner at it, and today I'll give you some encouragement and some tips based on my experience, to begin sketchnoting for yourselves. I spend an enormous amount of time in situations where I find it helpful to take notes: testing, talking to colleagues about a problem, reading, 1-1 meetings, project meetings, workshops, conferences, and, and, and, and I could go on. I've long been interested in the approaches I've evol...

Not Strictly for the Birds

One of my chores takes me outside early in the morning and, if I time it right, I get to hear a charming chorus of birdsong from the trees in the gardens down our road, a relaxing layered soundscape of tuneful calls, chatter, and chirrupping. Interestingly, although I can tell from the number and variety of trills that there must be a large number of birds around, they are tricky to spot. I have found that by staring loosely at something, such as the silhouette of a tree's crown against the slowly brightening sky, I see more birds out of the corner of my eye than if I scan to look for them. The reason seems to be that my peripheral vision picks up movement against the wider background that direct inspection can miss. An optometrist I am not, but I do find myself staring at data a great deal, seeking relationships, patterns, or gaps. I idly wondered whether, if I filled my visual field with data, I might be able to exploit my peripheral vision in that quest. I have a wide monito...

ChatGPTesters

The Association for Software Testing is crowd-sourcing a book, Navigating the World as a Context-Driven Tester , which aims to provide responses to common questions and statements about testing from a context-driven perspective . It's being edited by Lee Hawkins who is posing questions on Twitter , LinkedIn , Mastodon , Slack , and the AST mailing list and then collating the replies, focusing on practice over theory. I've decided to contribute by answering briefly, and without a lot of editing or crafting, by imagining that I'm speaking to someone in software development who's acting in good faith, cares about their work and mine, but doesn't have much visibility of what testing can be. Perhaps you'd like to join me? --00-- "Why don’t we replace the testers with AI?" We have a good relationship so I feel safe telling you that my instinctive reaction, as a member of the T...

Vanilla Flavour Testing

I have been pairing with a new developer colleague recently. In our last session he asked me "is this normal testing?" saying that he'd never seen anything like it anywhere else that he'd worked. We finished the task we were on and then chatted about his question for a few minutes. This is a short summary of what I said. I would describe myself as context-driven . I don't take the same approach to testing every time, except in a meta way. I try to understand the important questions, who they are important to, and what the constraints on the work are. With that knowledge I look for productive, pragmatic, ways to explore whatever we're looking at to uncover valuable information or find a way to move on. I write test notes as I work in a format that I have found to be useful to me, colleagues, and stakeholders. For me, the notes should clearly state the mission and give a tl;dr summary of the findings and I like them to be public while I'm working not just w...

Build Quality

The Association for Software Testing is crowd-sourcing a book, Navigating the World as a Context-Driven Tester , which aims to provide responses to common questions and statements about testing from a context-driven perspective . It's being edited by Lee Hawkins who is posing questions on Twitter , LinkedIn , Mastodon , Slack , and the AST mailing list and then collating the replies, focusing on practice over theory. I've decided to contribute by answering briefly, and without a lot of editing or crafting, by imagining that I'm speaking to someone in software development who's acting in good faith, cares about their work and mine, but doesn't have much visibility of what testing can be. Perhaps you'd like to join me? --00-- "When the build is green, the product is of sufficient quality to release" An interesting take, and one I wouldn't agree with in gener...

Postman Curlections

My team has been building a new service over the last few months. Until recently all the data it needs has been ingested at startup and our focus has been on the logic that processes the data, architecture, and infrastructure. This week we introduced a couple of new endpoints that enable the creation (through an HTTP POST) and update (PUT) of the fundamental data type (we call it a definition ) that the service operates on. I picked up the task of smoke testing the first implementations. I started out by asking the system under test to show me what it can do by using Postman to submit requests and inspecting the results. It was the kinds of things you'd imagine, including: submit some definitions (of various structure, size, intent, name, identifiers, etc) resubmit the same definitions (identical, sharing keys, with variations, etc) retrieve the submitted definitions (using whatever endpoints exist to show some view of them) compare definitions I submitted fro...

Express, Listen, and Field

Last weekend I participated in the LLandegfan Exploratory Workshop on Testing (LLEWT) 2024, a peer conference in a small parish hall on Anglesey, north Wales. The topic was communication and I shared my sketchnotes and a mind map from the day a few days ago. This post summarises my experience report. Express, Listen, and Field Just about the most hands-on, practical, and valuable training I have ever done was on assertiveness with a local Cambridge coach, Laura Dain . In it she introduced Express, Listen, and Field (ELF), distilled from her experience across many years in the women’s movement, business, and academia. ELF: say your key message clearly and calmly, actively listen to the response, and then focus only on what is relevant to your needs. I blogged a little about it back in 2017 and I've been using it ever since. Assertiveness In a previous role, I was the manager of a test team and organised training for the whole ...

Hiccupps

Search This Blog