Control and Observe

This week I was testing a new piece of functionality that will sanitise query parameters on an API endpoint. The developer had implemented a first cut and I was looking at the code and the unit tests for a few minutes before we got together for a walkthrough.

After exercising the new function through the unit tests, trying other values, and checking that the tests could fail, I wanted to send some requests from an external client. I already had the service set up in IntelliJ and running under the debugger, so ...

Sending requests from Postman and inspecting sanitised values in a breakpoint was OK, but there was too much jumping back and forth between applications, clicking on fields, scrolling and so on. Each iteration was many seconds long.

Luckily, we'd already decided to log sanitised strings for monitoring and later review, so I could disable the breakpoints and just look at the service console. That was better but still too heavy for me. There were many log lines and I had to find the one I was interested in and find the right field in it.

What I was looking for was a way to, in real time, run a request, see the sanitisation (or lack of it) immediately, and then try another request. I wanted to explore the implementation with minimal friction.

I wondered if I could get the console log out of IntelliJ to a file which I could then parse for the relevant log lines. A quick bit of Googling and it turns out I could! So I did! And then used this kind of command to pull out the sanitised text as it appeared:

$ tail -f /tmp/console.log | grep <my log line> | jq '.<sanitised text>'

I already had a tool that would let me submit requests with relevant input parameters. I built it when I first joined the company and I've been incrementally adding to it as I've needed new bits of functionality for testing.

This call would send "string" to the service to be sanitised and show the server response:

$ myrequest <string>

Now I had two windows in which I could see the request and response, whether there was sanitisation and, if so, what it was. One last thing, could I see both request and log at the same time? I thought I would take a second to learn how to split one iTerm2 terminal horizontally. Bingo!

This pattern is one that I use a lot, so much so that it's become internalised. I want to do both of these things:

control: the application, the environment, and the input
observe: the output and relevant internals

These are also two important testability considerations for system design in Rob Meaney's CODS model.

On top of that, I seek to minimise the friction in each iteration. I want the time between having an idea about what I want to test next to seeing the result to be short. In this way I can do more experiments in the same time and stay in flow.

Making a temporary test rig in the console this way has other benefits too, including a built-in history and easy copy-pasting into test notes, Slack, or bug reports.

Giving myself permission to experiment with the way of approaching the testing is also important here. I thought I would want to try enough inputs that it was worth investing in finding an efficient approach. This has the bonus that I learned a couple of things that will be useful again in future.

Syntax highlighting: pinetools

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...

How do I Test AI?

Recently a few people have asked me how I test AI. I'm happy to share my experiences, but I frame the question more broadly, perhaps something like this: what kinds of things do I consider when testing systems with artificial intelligence components . I freestyled liberally the first time I answered but when the question came up again I thought I'd write a few bullets to help me remember key things. This post is the latest iteration of that list. Caveats: I'm not an expert; what you see below is a reminder of things to pick up on during conversations so it's quite minimal; it's also messy; it's absolutely not a guide or a set of best practices; each point should be applied in context; the categories are very rough; it's certainly not complete. Also note that I work with teams who really know what they're doing on the domain, tech, and medical safety fronts and some of the things listed here are things they'd typically do some or all of. Testing ...

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...

Notes on Testing Notes

Ben Dowen pinged me and others on Twitter last week , asking for "a nice concise resource to link to for a blog post - about taking good Testing notes." I didn't have one so I thought I'd write a few words on how I'm doing it at the moment for my work at Ada Health, alongside Ben. You may have read previously that I use a script to upload Markdown-based text files to Confluence . Here's the template that I start from: # Date + Title # Mission # Summary WIP! # Notes Then I fill out what I plan to do. The Mission can be as high or low level as I want it to be. Sometimes, if deeper context might be valuable I'll add a Background subsection to it. I don't fill in the Summary section until the end. It's a high-level overview of what I did, what I found, risks identified, value provided, and so on. Between the Mission and Summary I hope that a reader can see what I initially intended and what actually...

On Herding Cats

Last night I was at the Cambridge Tester meetup for a workshop on leadership. It was a two-parter with Drew Pontikis facilitating conversation about workplace scenarios followed by an AMA with a group of experienced managers. I can't come to work this week, my cat died. Drew opened by asking us what our first thoughts would be as managers on seeing that sentence. Naturally, sadness and sympathy, followed by a week ? for a cat ? and I only got a day for my gran! Then practicalities such as maybe there's company policy that covers that , and then the acknowledgement that it's contextual: perhaps this was a long-time emotional support animal . Having established that management decisions are a mixture of emotion, logic, and contingency Drew noted that most of us don't get training in management or leadership then split us into small groups and confronted us with three situations to talk through: Setting personal development goals for others. Dropping a clange...

Reasonable Doubt

In Your job is to deliver code you have proven to work Simon Willison writes: As software engineers we ... need to deliver code that works — and we need to include proof that it works as well. He is coming at this from the perspective of LLM-assisted coding, but most of what he says applies in general. I think this is a reasonable consise summary of his requirements for developers: Manual happy paths: get the system into an initial state, exercise the code, check that it has the desired effect on the state. Manual edge cases: no advice given, just a note that skill here is a sign of a senior engineer. Automated tests: should demonstrate the change like Manual happy paths but also fail if the change is reverted. He notes that, even though LLM tooling can write automated tests, it's humans who are accountable for the code and it's on us to "include evidence that it works as it should." Coincidentally, just the week before I read his post I told one of my...

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...

Open Your Mind

Jerome Groopman, in How Doctors Think , reviews ways in which doctors can make poor choices, identifies potential causes, and suggests some practices, for both doctor and patient, that can help to prevent them. I find this interesting for a couple of reasons: first, I work in the health space, although not in a therapeutic area and, second, I like to reflect on my own thought processes. I'll take three broad themes from Groopman's analysis: the business of healthcare and how that impacts a physician's ability to practice; the doctor-patient relationship and how that impacts the experience of both sides; and the cognitive failings that impact a correct and timely diagnosis for any given patient. Naturally, these overlap. The book is written from the perspective of the notoriously commercialised American medical system and is around 20 years old, so doubtless some of the details are different outside of the US and have changed since pu...

Why Test, Test What, Then How?

There was a time when testing was all about the mnemonics . Well, we had no AI back then so thinking about our human craft and how to share what we had learned using our human intelligence with other engaged humans for later recall in their human heads seemed important. But this post isn't about dumping on AI. It isn't about mnemonics either even if WTTWTH does look like something that'd fit well into that ancient world. No, this post is just a snappier version of what I said to my team this week when I was walking through some testing I'd done the day before. It was concerned with a change to a particular turn in the dialog system we're building where multiple variables are in play, some populated by an external call to an LLM service. I wanted to make the point that the bulk of the testing work was done in the research I did and the spreadsheet I made, not in the interaction with our product. That spreadsheet was the result of me looking in our service's cod...

Better Isolate Than Never

How do you test a product with distributed logic and non-deterministic components? Well, it depends on the product and when the question is asked. This post is one answer, for now. A service I work on exposes an API for internal and external clients and calls multiple other services. It orchestrates a reasonably complex journey for a user, with their inputs and the responses of the services determining each step. Our customers can configure the service to provide a variant of the standard journey for their users. This gives them choices on the available steps, the order of the steps, and, importantly, some of the logic for taking particular steps. This configuration lives in a different repository to the service, not owned by us, and it can be changed and deployed independently from the service. As you can imagine, we test our service in multiple ways at different granularities using the usual tooling, including unit tests fo...

Hiccupps

Search This Blog