Both knapsack and parallel_tests have the option to split groups by historic execution time. The required logs for this might be outdated since you manually have to update and push them into your repository.

The following card includes an option how you can keep them consistently up to date with no extra effort locally and/or remotely.

How to always split by execution logs

Parallel Tests

The parallel_tests gem has the option flag `--group...

For my computer science bachelor's thesis I programmed and evaluated a CLI Test Case Prioritization (TCP) tool for makandra. It has been written as a Ruby Gem and was tested and evaluated against one Ruby on Rails project. This card will summarize and present the research results, the evaluation and the programmed CLI tool.

The code has been published for educational purposes on GitHub. The german bachelor's thesis has also been included for download at the end.

...

It is a common misunderstanding that all [op]=-operators work the same way, but actually they don't.

||= and &&=

Those are special cases, because the assignment will only happen if the first variable passes the check (false or nil for || and true for &&).

a ||= b   # => a || (a = b)
a &&= b   # => a && (a = b)

But still, if reading a has any side effects, they will take place regardless of to what a resolves.

Other [op]=

Assignment will always take place, no matter the value of a.

Geordi's cucumber command has a --rerun option that reruns failing tests the given number of times. Usage:

geordi cucumber path/to/features --rerun=2
geordi cucumber path/to/features -r2

Background and how to rerun manually

Cucumber will save a file tmp/parallel_cucumber_failures.log containing the filenames and line number of the failed scenarios after a full test run. Normally you can say cucumber -p rerun (rerun is a profile defined by default in config/cucumber.yml) to rerun all failed scenarios.

Here are a few al...

The git doc states on the difference of these two commands:

• git-restore[1] is about restoring files in the working tree from either the index or another commit. This command does not update your branch. The command can also be used to restore files in the index from another commit.
• git-reset[1] is about updating your branch, moving the tip in order to add or remove commits from the branch. This operation changes the commit history.

git reset can also be used to restore th...

There are multiple ways to redirect URLs to a different URL in Rails, and they differ in small but important nuances.

Imagine you want to redirect the following url https://www.example.com/old_location?foo=bar to https://www.example.com/new_location?foo=bar.

Variant A

You can use ActionController::Redirecting#redirect_to in a controller action

class SomeController < ActionController::Base
  def old_location
    redirect_to(new_location_url(params.permit(:foo))) 
  end
end

This will:

• It will redirect with a 302 st...

Rails' url_for is useful for generating routes from a Hash, but can lead to an open redirect vulnerability.

Your application's generated route methods with a _url suffix are also affected because [they use url_for unter the hood](https://github.com/rails/rails...

Rails' Strong Parameters enable you to allow only specific values from request params to e.g. avoid mass assignment.

Usually, you say something like params.permit(:email, :password) and any extra parameters would be ignored, e.g. when calling to_h.
This is excellent and you should definitely use it.

What is permit! and why is it dangerous?

However, there is also params.permit! whic...

There are various ways to run external commands from within Ruby, but the most powerful ones are Open3.capture3 and Open3.popen3. Since those can do almost everything you would possibly need in a clean way, I prefer to simply always use them.

Behind the scenes, Open3 actually just uses Ruby's spawn command, but gives you a much better API.

Open3.capture3

Basic usage is

require 'open3'

stdout_str, error_str, status = Open3.capture3('/some/binary', 'with', 'some', 'args')
if status.success?...

In a nutshell: Use git rebase --onto target-branch source-commit

• target-branch means "branch you want to be based on"
• source-commit means "commit before your first feature commit"

Let's say my-feature-branch is based on master and we want it to be based on production. Consider this history:

%%{init: { 'gitGraph': {'showCommitLabel': true, 'mainBranchName': 'production'}} }%%

gitGraph
  commit id: "1"
  commit id: "2"
  branch master
  commit id: "3"
  commit id: "4"
  branch my-feature...

It might sound trivial, but there is no such thing as a "hover" or "mouseover" state on touch devices. If your application is supposed to work on iPads, smartphones, etc., don't hide information behind a tooltip, and don't make controls appear when hovering over another element.

Generally, things that happen/appear when you hover an element should do the same when you click the element.

Newest versions of Chromedriver breaks the user agent for device emulation via device name. In previous versions the user agent of the emulated device was set. In the newest versions the user agent differs from the emulated device.

• Version Chrome: 116.0.5845.110
• Version Chromedriver: 116.0.5845.96
• Bug: https://bugs.chromium.org/p/chromedriver/issues/detail?id=4550&q=userAgent&can=2
• Setting: https://chromedriver.chromium.org/capabilities

In Capybara an affected config looks like following:

Capybara.register_driver :mobi...

Capybara allows you to filter elements that are focused.

page.find(:fillable_field, focused: true) # Filtering only fillable inputs for performance reasons
page.find(:xpath, '//*', focused: true) # Filter all fields

Legacy approach

In older version, it was possible to use the :focus pseudo-class. This seems not to work in newer versions anymore.

find(':focus')

In the linked page, Manuel Matuzović offers an FAQ regarding web components, and their accessibility in particular.

At time of writing this card, the post is still work in progress and will expand over time.

I can also recommend his blog in general.

In CI test runs I noticed that string sorting order changed after switching from a debian-based PostgreSQL docker image to one that is based on Alpine Linux.

Debian image sorting: bar Bar foo Foo
Alpine image sorting: Bar Foo bar foo

Explanation

Alpine Linux is a very slim linux distribution that results in small docker image sizes (roughly 100MB instead of 150MB), so it's a popular choice. However, it does not have all comman locales installed and does not use all locales that a user installs by default.
Postgres orders string co...

An introduction to mangling

When you minify ("compress", "optimize") your JavaScript for production, the names of your functions and variables will be renamed for brevity. This process is often called mangling.

E.g. if this is your source code:

function function1() {
  function2()
}

After mangling it would look like this:

function a() {
  b()
}

Object properties are not mangled by default

Minfiers never mangle properties by default, as this can be an unsafe transformation. This leads to larger file sizes if...

While debugging a SPF record I found spf-record.de to be very helpful.

• it lists all IPs that are covered by the SPF record
• shows syntax errors
• helps you debugging errors like DNS lookup limit reached
• it also lets you test a new SPF strings before applying it. This can save you time as you don't have to loop with operations

Also the advanced check at vamsoft.com has a very good interface to test new SPF policies.

A HTTP 302 Found redirect to PATCH and DELETE requests will be followed with PATCH or DELETE. Redirect responses to GET and POST will be followed with a GET. The Rails form_for helper will use a workaround to send POST requests with a _method param to avoid this issue for PATCH/DELETE.

If you make requests yourself, watch out for the following behavior.

When you make an AJAX request PATCH /foo and the /foo action redirects to /bar, browsers will request PATCH /bar. You probably expected the second requ...

There is a common view that extracting text from a PDF document should not be too difficult. After all, the text is right there in front of our eyes and humans consume PDF content all the time with great success. Why would it be difficult to automatically extract the text data?

Turns out, much how working with human names is difficult due to numerous edge cases and incorrect assumptions, working with PDFs is difficult due to the extreme flexibility given by the PDF format.

You can tell npm to install a package globally with npm -g install @puppeteer/browsers. However, it seems that its not possible that npx can run commands from global packages without referencing the global package path.

Example

Installing @puppeteer/browsers globally:

$ npm -g install @puppeteer/browsers

The globally installed package @puppeteer/browsers can not be access via npx:

$ npx --no-install @puppeteer/browsers

npm ERR! canceled # Error message when package is not installed

But it is installed g...

Background

Rails offers several methods to manage three types of different cookies along with a session storage for cookies. These are normal, signed and encrypted cookies.

By following the happy path of testing a web application, that is only the main use-case is tested as a integration test and the rest as isolated (more unit ...

To ensure Spring is not running:

bin/spring stop
pkill -f spring

To prevent Spring from starting again:

export DISABLE_SPRING=1

Background information about session storage in Rails

Rails has a default mechanism to store the session in the CookieStore. This is a cookie which holds the entire user session hash in the browser. This cookie is serialized, encoded with base64, and signed.

How Devise handles authentication

Devise uses this CookieStore. To track a users session, a salt is stored in the session ...

The Node Version Manager allows installing multiple NodeJS versions and switching between them.
By default, it does not automatically switch versions when entering a directory that holds a .nvmrc file.

The project's readme document offers a bash function which calls nvm use after each cd. In fact, it replaces cd in your bash.

I did not want to do that, but instead use the $PROMPT_COMMAND feature. So here is my take on it.
Note that it is much shorter, it probably does a f...