Upgrade Rails from 3.2 to 4.0

This article is part of our Upgrade Rails series. To see more of them, click here.

A previous post covered some general tips to take into account for this migration. This article will try to go a bit more in depth. We will first go from 3.2 to 4.0, then to 4.1 and finally to 4.2. Depending on the complexity of your app, a Rails upgrade can take anywhere from one week for a single developer, to a few months for two developers.

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AWS S3 Policies for Carrierwave

When you create IAM credentials and policies for your app, you should make sure that they have access to the resources that they need and not more than that!.

This way, if anyone gets access to those credentials, the impact of this leak is reduced to the resources associated with them (and not all the buckets in your S3 account)

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'Flaky' tests: a short story

One of the hardest failing tests to debug are those which fail randomly, also known as "flaky" tests. You write your test cases, you run the tests in your environment (in random order), and see them all pass. Afterwards, you push your code, your CI server runs them and one test fails.

This is not an uncommon scenario, and one too common when using integration tests which use JS, with Capybara-Webkit or Selenium. But if your failing test doesn't communicate with an external API, doesn't use JS, and passes locally, it can be a bit nerve-wracking.

After you have identified the failing test, and it still passes after running it locally, one way to figure out why it's failing is running its context multiple times.

To automate this process a bit, I like to use the following command:

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How to run multiple dependent builds on Circle CI

We all know the importance of having a CI tool integrated in your project. It allows you to run your entire test suite every time you want to merge a set of changes. If you have a core project and many projects that depend on it, you want to run the tests for the core project and the dependent projects at the same time. This article explains how you can do it with Circle CI.

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How to test a React app using capybara-webkit

I have been using the capybara-webkit gem for a while now since I first tried it out after making the switch from Capybara + Selenium.

Using capybara-webkit speeds up my Selenium tests due to its headless nature, and it's very straightforward. However, I had some trouble testing a Rails based React app.

In this post, I will explain how I worked around the issues that came up when trying to use capybara-webkit with React.

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Announcing AfipBill

If you live in Argentina and you ever use AFIP, you should already know that their platform is not the best in terms of user friendliness. We wanted to integrate OmbuShop with AFIP (using their API) in order to generate and print the bills for each seller. Unfortunately, there is no way to do this because the API doesn't generate a printable version (PDF) of the bill.

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How to use any gem in the Rails production console

How many times did you come across a great gem you wanted to try out in a production console, like benchmark-ips or awesome-print?

Be it for performance or for readability, sometimes it's nice to be able to try out something new quickly without going through a pull request + deployment process. This is possible by modifying the $LOAD_PATH Ruby global variable and requiring the gem manually.

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Present? vs Any? vs Exists?

When working on a Rails project, you may have seen present? calls on ActiveRecord relationships. This might feel natural, mostly because present? exists on all objects via ActiveSupport, so you expect the relationship to respond to it, but it's actually not a very good idea. If all we want to do is check if the scope returns any results from the database, there are better ways than using present?.

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Brief look at RSpec's formatting options

A few weeks ago, I noticed weird output in the RSpec test suite (~4000 tests) for a Rails application:

.............................................................................................unknown OID 353414: failed to recognize type of '<field>'. It will be treated as String  ...........................................................................................................................................

This Rails app uses a PostgreSQL database. After some Googling, it turns out that this is a warning from PostgreSQL. When the database doesn't recognize the type to use for a column, it casts to string by default.

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