V is a language I’ve been playing around with very recently and I’ve been looking for a new project to get stuck into. So I thought it was time to build another SQL database to get a feel for the language, but also provide a worthy database for the V community:

https://github.com/elliotchance/vsql

Really, another SQL database… is that really necessary? Well, yes, I think so. The goals are (all of which are implemented):

1. vsql is written with in pure V with no dependencies, including V dependencies.
2. vsql can be embedded (like SQLite3) with the entire database stored in a single…

I’m a big fan of TDD. BDD has always been a bit elusive to me in the sense that I wish I could use it more often. However, I always seem to end up struggling to express the same nuances through BDD that come effortlessly through a standard test case.

Truth be told, I have’t touched BDD in a while. However, this question has been bouncing around my head lately:

Why is it often so difficult to express simple systems through BDD?

Code based tests are really good at describing how we complete a task. BDD is really good at…

Go’s error handling is very explicit. It can also be very verbose compared to other languages. I want to talk about how we can minimize the need for explicit error handling by separating what are expected and unexpected errors.

Expected Errors

An expected error is generally something you can test/check/verify ahead of time or that would not have a detrimental effect on the system. Some examples of expected errors are:

1. Validating an email address from an input.
2. Verifying that a user has access to a certain part of the system.
3. Retry on a known flaky or slow API endpoint.

Expected errors should…

Go does not have any concept of enums like some other languages. There are arguments for and against this approach which I won’t go into here. However, there are times when you want to check that switch statements contain all enum values. Especially if you intend to add new enum values in the future and want to catch existing code that now needs to be updated accordingly.

For this, I developed a tool called switch-check. It’s a zero dependency, zero configuration CLI tool for doing just that. You can try it right now with:

go get -u github.com/elliotchance/switch-check
switch-check

Or…

It’s a common scenario — for me at least — to be building a CLI tool (main package) that has CLI options (flags package) that I want to add unit tests to.

Here’s a simple example of a CLI tool that adds or multiplies some input numbers:

Let’s try it:

5 + 7 + 9 = 21 — great… But wait! 3 * 2 * 5 != 0…I’ve put a deliberate bug in the command. Something that we will catch and fix with a unit test.

Don’t Try This At Home Kids

Let’s write a unit test that uses the same CLI arguments so…

An ordered map (also called a linked hash map in Java) is a data structure that allows amortized O(1) for access and mutation just like a map, but the elements maintain their order.

For this I created the github.com/elliotchance/orderedmap package. Here is some basic usage:

m := orderedmap.NewOrderedMap()// Keys and values can be any type.
m.Set("foo", "bar")
m.Set("qux", 1.23)
m.Set(123, true)m.Delete("qux")value, exists := m.Get("qux")

The most important feature of the *OrderedMap is that the order of the keys is maintained, so that we can iterate them in their creation order:

for _, key := range m.Keys() {…

Go ships with great tools for runtime performance monitoring. However, for one of the projects I am working on I needed tailored metrics around three channels that do the primary communication between the larger components of the processing service.

I wanted to be able to print realtime stats on movement and blocking of these channels only each minute. So I created ChannelPerf :

https://gist.github.com/elliotchance/7db9eb40a935f5526b62f0bcf77b7d2c

How does it work?

For the most part it is a drop in replacement-ish with how you would normally use a channel:

// ch := make(chan interface{}, 1)
ch := NewChannelPerf(1, "Some name")// ch <- "foo"
ch.Send("foo")// next…