Write commit messages with the future in mind
Want to write more helpful commit messages? Write with the future in mind, and you'll also write better messages for the present.
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Avoid test setup pollution (and 4 problems it creates)
One problem with shared setup in Elixir is that it can pollute our tests: creating unused data, introducing mystery guests, requiring extra database operations, and obscuring critical information.
How LiveView got rid of dangling processes in tests – and how we can do the same
Back in LiveView 0.12, testing a LiveView connected to the database would sometimes result in our test passing but us seeing the Dreaded Wall of Red Text. Then, in LiveView 0.13.0 those errors were gone. How?
Is the test LiveView immutable or not?
Someone from my Testing LiveView course recently asked me about the immutability of the `view` we get from `live/2` in LiveView tests.
It's not the first time someone's asked me that question, so I wanted to try to clarify things a bit.
Minimize context loss when opening a Pull Request
You're working in a codebase. You stumble upon something you'd like to change. The code change will only take 2 minutes.
Do you make the change and open a Pull Request?
The answer likely depends on how costly it is to open that Pull Request. And that cost is commensurate with the loss of context of our current work.
Reduce the friction of executing a test
To practice test-driven development (TDD), I recommend developers reduce the friction involved in running an individual test.
Since TDD uses test failures as guidance for implementation, it is most helpful when we have a tight feedback loop. But if running tests takes a long time, we don't run them as frequently, and we miss out on the tests' feedback.
Ecto's uniqueness constraint vs Rails' uniqueness validation
I really like how closely Ecto integrates with our database. That was a surprising difference when I first came from Rails.
Ecto’s constraints are a great example of that. Like Rails, Ecto has validations. But unlike Rails, Ecto also has constraints. Validating uniqueness is the example that most easily comes to my mind.
Using ExUnit's `start_supervised/2` for better cleanup
In a previous post, I wrote about how we can test a named singleton process in our system. There's one more improvement we can make for better cleanup.
TDD changes code design from invention to discovery
I was reading the paper Mock Roles, not Objects, and there's a description of TDD that captures an important concept I haven't been able to put into words before: TDD changes code design from invention to discovery.
Mocking External Dependencies in Elixir
A reader recently asked me about mocking external dependencies in Elixir. So, I wanted to discuss two popular mocking libraries and how to mock without a library (and which option I like best).
Dependency Inversion with Elixir Protocols
I've always liked the Dependency Inversion Principle (DIP). Once understood, it helps us decouple code in surprising ways. Let's take a look at how Elixir protocols decouple code through DIP.
Using mix aliases to improve your workflow
When developers onboard new projects, we are uniquely positioned to help improve the onboarding experience for future developers. So, when I join a new project, I relish the opportunity to clarify and simplify setup instructions.
elixir lunch is now elixir social
elixir lunch is now elixir social. I renamed it because very few people brought lunch 😅. It seems most weren't interested in that part. But they were interested in hanging out with other Elixirists. So, I figured I'd roll with the punches.
Testing Singleton Processes with Dependency Injection
Named singleton processes are wonderful for Elixir applications, but they often make it hard to test their behavior. Since singletons are started as part of the supervision tree, they become a globally shared resource for our tests. And that can lead to intermittently failing tests due to race conditions.
Starting elixir lunch
I've been thinking of starting something called "elixir lunch" for some time – a low-key lunch gathering of Elixirists. Now, let's make it happen.
Taking LiveView's JS commands for a spin
I'm excited about LiveView's JS commands (introduced in 0.17.0) because they allow us to express JavaScript within our LiveView code. And that makes it easier to create certain types of interactions.
BDD and just-in-time development
Behavior-driven development (BDD) has a powerful by-product – building just what we need to support our customers. Nothing more.
New to Elixir? Beware of Date and DateTime Comparisons!
People new to Elixir, especially those coming from Ruby, might be surprised at how Elixir dates and datetimes are compared. It's easy to introduce a subtle yet dangerous bug.
Lateral Joins Instead of Window Functions
If you need to use window functions, try a lateral join first! It's Postgres's equivalent of a `for_each` function.
What is Elixir? For my Ruby friends.
Many Ruby friends think of Elixir as just a functional Ruby. So they see it, maybe try it, and walk away. But that's just the surface. Beneath the surface, Elixir brings a runtime system that we can design and control to build applications that heal themselves.
7 GUIs: Implementing a CRUD App in LiveView
I want to see how to handle 7 GUI tasks in LiveView. Here are the highlights from implementing the fifth task: a CRUD application.
Project-wide find and replace in Vim
A recipe to find and replace across a project in Vim.
CSS Selectors for Tests
Testing web pages often requires targeting elements with CSS selectors. But which CSS selectors should we use? Are some better than others? I think so.
7 GUIs: Implementing an Interactive Timer in LiveView
I want to see how to handle 7 GUI tasks in LiveView. Here are the highlights from implementing the fourth task: an interactive timer.
7 GUIs: Implementing a Flight Booker in LiveView
I want to see how to handle 7 GUI tasks in LiveView. Here are the highlights from implementing the third task: a flight booker.
I'm going on a consulting adventure!
After years of working with thoughtbot, I've decided to go on a solo consulting adventure.
7 GUIs: Implementing a Temperature Converter in LiveView
I want to see how to handle 7 GUI tasks in LiveView. Here are the highlights from implementing the second task: a temperature converter.
7 GUIs: Implementing a Counter in LiveView
I want to see how to handle the 7 GUI tasks in LiveView. So here are the highlights from implementing the first task: a counter.
Deadlines vs Appetite
One of the concepts I found most interesting about Shape Up is the concept of appetite. Like a deadline, appetite talks about the amount of time we're going to spend on a feature or project. But the process is wonderfully reversed.
Keeping the same path helpers when turning a view into a LiveView
Want to change a regular view to a LiveView, but you don't want to change all those path helpers? I got you covered.
Culture is a 50-day moving average
In a recent interview, Jason Fried said that culture is a 50-day moving average of our actions. That is incredibly freeing and compelling.
Using has_element?/3 for better LiveViewTest assertions
It's tempting to write `LiveViewTest` assertions that specify too much of our HTML. But that couples our tests to the implementation specifics. There's a better way: the `has_element?/3` helper can help us be specific without adding coupling.
A minimalist LiveView testing guide
Let's apply Sandi Metz's minimalist unit testing guide to LiveView. There are so many parallels and our tests benefit from Sandi's wisdom.
TDD Phoenix Update (Nov 2020)
An update on progress and changes to TDD Phoenix since August.
Testing LiveView talk and course
This year I presented a Testing LiveView talk at ElixirConf 2020. The video and my slides are now online.
Break apart your features into full-stack slices
Our communication practices can be very disrupting. Remote work has taught me to be more considerate of how I communicate with others. We should treat other people's time as we like ours to be treated.
Pay the cost up front. Don't distribute it to others.
Our communication practices can be very disrupting. Remote work has taught me to be more considerate of how I communicate with others. We should treat other people's time as we like ours to be treated.
Beyond basic modal editing. Using vim's command-line mode.
Most people learn vim's `normal`, `insert`, and `visual` modes. But they're only casually acquainted with vim's powerful Ex commands. Let's take a look at some.
TDD Phoenix — update on a work in progress
I've been writing a TDD Phoenix book. It's still a work in progress, but it's freely available online. This is a short update on progress and plans.
On Quitting Vim
Vim has a reputation for being hard to quit. But it turns out there are so many ways to get out of it — it's like vim wants you to quit. Let's look at a few.
Remote Tools and Tips in These Remote Times
Some tools and tips for remote collaboration from my experience being remote over the last two years.
Breaking Out of Ecto Schemas
With Ecto, 🎶 you _can_ always get what you want. And if you try sometimes, well, you might find, you can _select_ want you need 🎶.
Splitting a Commit
My workflow usually involves squashing many commits into a single one. But sometimes, the workflow calls for the opposite action -- splitting a single commit into many. This is how I do it.
5 Tips for More Helpful Code Reviews
Having your code reviewed can be daunting. But it can also be very helpful. As reviewers, we can make the difference. Here are five tips to make your code reviews more helpful to the author.
Faking External Services in Tests with Adapters
When faking external services in tests, start with something simple. I like having a public interface to adapters and having an in-memory adapter for tests. Let me show you an example.
Supercharge Your Elixir and Phoenix Navigation with vim-projectionist
Toggle between alternate files, edit files by type, and create files with templates — all with `vim-projectionist`. If you've never used it, you're in for a treat.
Finding the Time to Refactor
Many people ask, "How do I find time to refactor?" I think the question itself betrays a misunderstanding of refactoring. Let me tell you when I refactor.
Dumpster Diving through Dotfiles: Remote Git Branches
Don't let your git repo become a graveyard of stale branches. But how do you even know what branches are there? Let me introduce you to `git branches`.
Let's Not Misuse Refactoring
Refactoring has a specific meaning. When we misuse the word, we lose the ability to communicate an important concept. Let's revisit what refactoring is and what it is not.
Better domain modeling in Elixir with sum types
Sum types are a powerful domain modeling technique. Let’s look at how to use them to remove invalid states.
Dumpster Diving through Dotfiles: Better Git Logging
There are pearls to be found. Check out these git logs.
Back to basics: psql
The right tool for the right job, right? Well let me introduce you to psql.
Say no to more process, say yes to trust
Adding policies is easy. Removing them is difficult. Say no to more process. Trust your team instead.
A couple of Elixir videos on Upcase
Recently, thoughtbot decided to make Upcase free. It has a lot of great learning materials, especially when it comes to Rails, vim, test-driven development, and tmux.
Do you break your Elixir eggs on the big end or the little end?
From big-endian to little-endian through unsigned integers. A tale of two ends, and Elixir shines again.
Don't forget the silent step when you squash and merge
GitHub’s squash and merge button is great. But make sure to write a good commit message before you confirm those changes.
Is Elixir a scripting language?
Elixir is known for being a language made for building distributed applications that scale, are massively concurrent, and have self-healing properties. But is Elixir good enough for the mundane scripts of this world?
Write good commit messages by blaming others
To write good commit messages, you must read commit messages. And to read commit messages, you must use `git blame` effectively.
Long-lived processes in Elixir
Long-lived processes are everywhere in Elixir. Let’s look at why they’re needed and how to create them!
Build your own web framework in Elixir (video)
How to organize your functional code
When coming from object-oriented languages, I often hear people ask the question, “How do I organize my code? Modules are just bags of functions!”. That is a question I asked myself as well, but after using Elixir and Elm for a while, I have noticed that there is a principle of organization that I keep using and that I see in the wild. I like to think of it as the principle of attraction.
An introduction to concurrency in Elixir
Concurrency is a first-class citizen in the Elixir platform. The concurrency model is that of isolated, independent processes that share no memory and communicate via asynchronous message passing. In other words, a process can run concurrently without concern of others, and processes communicate with each other only via send-and-forget messages.
Tests as Counselors of Design
One of the benefits of tests is that they are the first piece of code that will interact with our application. As such, they can offer valuable insights into the application's complexity.
Elixir simple_one_for_one Supervisors
Supervision trees are awesome. For a while I was a bit confused as to how to use the simple_one_for_one
supervision strategy. Let’s look at it step by step by creating a simple
bank account from which we can deposit and withdraw money.
Tests as Tools for Understanding
When working on a feature, I often find pieces of code that I have not seen before. In order to better understand the class or method, I like to use tests as documentation and as a way to explore the code's functionality.