RubyMine allows bookmarking lines of code. This is super-helpful when working on a complex problem.
I've been using this feature for a few years now, and so should you! :)

Here are the default Linux/Windows keystrokes. See the documentation for other keybindings.

Add an anonymous bookmark

F11

A gray checkmark will be shown in the gutter on the left.
If you press F11 again on a bookmarked line, the bookmark will be removed.

Add a named bookmark ("mnemonic")

Ctrl ...

Looks like ActiveState is trying to market a new Ruby distribution for Enterprises:

ActiveRuby Enterprise Edition is designed for businesses with large Ruby deployments in essential, mission-critical applications that, when down, could cost your business in lost revenue and a damaged reputation. Deploy Ruby with confidence knowing you're using the most secure, enterprise-grade builds for the platforms that power your business. You'll get priority access to our Ruby experts for technical support and best prac...

The postMessage API is an alternative to JSONP, XHR with CORS headers and other methods enabling sending data between origins. It was introduced with HTML5 and like many other cross-document features it can be a source of client-side vulnerabilities.

The pages listed here contain tests and experiments about features, possibilities, browsers’ bugs concerning CSS.

That is, over 200 experiments.

Line-height and vertical-align are simple CSS properties. So simple that most of us are convinced to fully understand how they work and how to use them. But it’s not. They really are complex, maybe the hardest ones, as they have a major role in the creation of one of the less-known feature of CSS: inline formatting context.

For example, line-height can be set as a length or a unitless value 1, but the default is normal. OK, but what normal is? We often read that it is (or should be) 1, or maybe 1.2, even the CSS spec is unclear on that...

There seems to be a nasty bug in Chrome 56 when testing with Selenium and Capybara: Slashes are not written to input fields with fill_in. A workaround is to use javascript / jquery to change the contents of an input field.

Use the following code or add the attached file to your features/support/-directory to overwrite fill_in.

module ChromedriverWorkarounds

  def fill_in(locator, options = {})
    text = options[:with].to_s
    if Capybara.current_driver == :selenium && text.include?('/')
      # There is a nasty Bug in Chrome ...

If the application under test makes sound, you probably want to disable this during integration testing.

You can use the args option to pass parameters to the browser. For Chrome:

Capybara.register_driver :selenium do |app|
  Capybara::Selenium::Driver.new(app, browser: :chrome, args: ["--mute-audio"])
end

I haven't found a corresponding command line option for Firefox.

Hat tip to kratob.

We generally use multiple application servers (at least two) and you have to search on all of them if you don't know which one handled the request you are looking for.

Rails application logs usually live in /var/www/<project-environment-name>/shared/log.
Web server logs usually live in /var/www/<project-environment-name>/log.

Searching through single logs with grep / zgrep

You can use grep in this directory to only search the latest logs or zgrep to also search older (already zipped) logs. zgrep is used just like grep ...

Sometimes huge refactorings or refactoring of core concepts of your application are necessary for being able to meet new requirements or to keep your application maintainable on the long run. Here are some thoughts about how to approach such challenges.

Break it down

Try to break your refactoring down in different parts. Try to make tests green for each part of your refactoring as soon as possible and only move to the next big part if your tests are fixed. It's not a good idea to work for weeks or months and wait for all puzzle pieces ...

In general, you should not put a block element inside an inline element. So don't do this:

<span>
  <div>text</div>
</span>

The browser will think you wrote invalid HTML by accident, and will sometimes reorder elements silently.

There is one notable exception: It's OK to wrap block elements in a <a> tag in HTML5 (not 4). The spec says:

The a element may be wrapped around entire paragraphs, lists, tables, and so forth, even entire sections, so long ...

Like you know from "How to tell ActiveRecord how to preload associations (either JOINs or separate queries)", you can tell ActiveRecord explicitly if it should use a LEFT OUTER JOIN or a separate query to preload associations.

Here is some special case, where a simple includes is not possible. For the diagram below we want to sort the rides by the translated name of the departure_place and the arrival_place:

![6020905239052288.png](https://makandracards.com/makandra/43252-howto-combine-custom-sql-with-preload/a...

xargs is a powerful bash tool that can take input from $STDIN and pass it to a given command. I.e. you can do the following:

$> cat tmp/parallel_cucumber_failures.log
features/authentication.feature:33
features/backend/pages.feature:5
features/backend/pages.feature:60

$> cat tmp/parallel_cucumber_failures.log | xargs geordi cucumber
# Running features
> Only: features/authentication.feature:33 features/backend/pages.feature:5 features/backend/pages.feature:60
...

Beside the linked article you might also be interested in reading ...

If your external displays not switching on or showing a weird behavior (for e.g. all displays getting the same configuration all the time) you can fix it by switching off all external displays and re-enabling only one in the first step. Afterwards you can apply your whole configuration via xrandr. This behavior could be a bug in the kernel and may be fixed in linux 4.8.

Example display configuration

Screen 0: minimum 8 x 8, current 5760 x 1200, maximum 32767 x 32767
eDP1 connected 1920x1080+0+0 (normal left inverted right x axis...

There is no CSS selector for matching elements that contains a given string ¹. Luckily, Capybara offers the :text option to go along with your selector:

page.find('div', text: 'Expected content')

You can also pass a regular expression!

page.find('div', text: /Expected contents?/i)

Note that if your CSS selector is as generic as div, you might get a lot more results than you expect. E.g. a <div class="container"> that surrounds your entire layout will probably also contain that text (in a descendant) and ...

Yesterday I stumbled across a talk in which the guy mentioned module sub-classing. I was curious what you can do with it and found his blog post with a cool example. It allows you to inject some state into the module you are including elsewhere. Check it out!

class AttributeAccessor < Module
  def initialize(name)
    @name = name
  end

  def included(model)
    super
    define_accessors
  end

  private

  def define_accessors
    ivar = "@#{@name}"
    define_writer(ivar)
    define_reader(ivar)
  end

  def define_writer(ivar)
    ...

When working with custom transactions and use ActiveRecord::Rollback you may encounter unexpected behaviour if you try to roll back your changes.

tl;dr

When using nested transactions, ActiveRecord::Rollback might not do what you expect, since it will only roll back the inner, but not the outer transaction.

You can fix this behavior by using transaction(joinable: false) but this leads to a bunch of different problems.

When you don't need an explicit ActiveRecord::Rollback, don't worry about any of this and just use a plan `tran...

SVG is an acronym for "scalable vector graphics". SVGs should be used whenever an image can be described with vector instructions like "draw a line there" or "fill that space" (they're not suited for photographs and the like). Benefits are the MUCH smaller file size and the crisp and sharp rendering at any scale.

It's a simple, old concept brought to the web – half-heartedly. While actually all browsers pretend to support SVG, some barely complex use cases get you beyond common browser support.

In the bas...

We have released a new library Gemika to help test a gem against multiple versions of Ruby, gem dependencies and database types.

Here's what Gemika can give your test's development setup (all features are opt-in):

• Test one codebase against multiple sets of gem dependency sets (e.g. Rails 4.2, Rails 5.0).
• Test one codebase against multiple Ruby versions (e.g. Ruby 2.1.8, Ruby 2.3.1).
• Test one codebase against multiple database types (currently MySQL or PostgreSQL).
• Compute a matrix of all possib...

Same requests are recorded only once in vcr. Replaying a test fails, if you trigger the same request multiple times. The error message is somehow confusing, as your cassette contains the request:

An HTTP request has been made that VCR does not know how to handle

If you want to allow to match a request multiple times, you need to configure this explicit with allow_playback_repeats: true. Some exa...

Similar to our snippet that runs all Cucumber features matching a given string, the following will run all modified or new Cucumber features by looking at your git status:

git status --short | grep -v '^ D ' | grep '.feature' | sed 's/.. //' | tr '\n' ' ' | xargs geordi cucumber

If you want to know what each of the above commands does, see [explainshell](http://explainshell.com/explain?cmd=git+status+--short+%7C+grep+-v+%27%5E+D+%27+%7C+grep+%27.feature%27+%7C+sed+%27s%2F..+%2F%2F%27+%7C+tr+%27%5Cn%27+%27+%27+%7C...