Debugging AJAX requests with better_errors
better_errors
is an awesome gem for enhanced error pages in development, featuring a live-REPL for some light debugging.
To debug the exception you got on an AJAX-Request, visit /__better_errors
on your app's root path (e.g. http://localhost:3000/__better_errors
). It shows the error page for the last exception that occurred, even when it has been triggered by an AJAX request.
CSS: How to force background images to scale to the container, ignoring aspect ratio
You can scale background images in CSS to the container size using background-size
(Demo).
Commonly, we use contain
or cover
because we want to preserve the image's aspect ratio.
If you do not want to do that, simply provide scaling values for X and Y:
background-size: 100% 100%
(a simple 100%
would mean 100% auto
and respect the image's aspect ratio)
SVGs with a viewBox will force their aspect ratio
The above may not work for you when ...
Ruby: What extend and include do
All Rubyists should be familiar with the common definitions for include and extend. You include a module to add instance methods to a class and extend to add class methods. Unfortunately, this common definition isn’t entirely accurate. It fails to explain why we use instance.extend(Module) to add methods to an instance. Shouldn’t it be instance.include(Module)? To figure this out we’re going to start by discussing where methods are stored.
- include: Adds methods from the provided Module to the object
- extend: Calls include on the single...
Setting SASS variables as value for CSS custom properties
When using custom properties in your stylesheets, you may want to set a specific property value to an existing variable in your SASS environment. A pratical example would be a list of color variables that you've defined in colors.sass
and that you would like to refer to in your stylesheets. However, simply assigning a variable will not work:
$my-great-blue: blue
:root
--my-color: $my-great-blue
.sky
background-color: var(--my-color)
The property value will not be valid and if you open the browser's inspection window, yo...
Headless Chrome: Changing the Accept-Language header is not possible
It seems like changing the HTTP_ACCEPT_LANGUAGE
is not possible for a headless chrome.
- On Ubuntu the headless Chrome derives the Accept-Language from the operation system
- Adding the option
options.add_argument('--lang=de')
to theCapybara::Selenium::Driver
has no effect - Adding the preference
options.add_preference('intl.accept_languages', 'de')
to theCapybara::Selenium::Driver
has only effects if the--headless
option is skipped (see bug ticket #775911) - Cha...
Selenium: Network throttling via Chromedriver
You can throttle the network in your headless chrome via Selenium. This might be useful for debugging issues with flaky integration tests or slow page simulations.
page.driver.browser.network_conditions = {offline: false, latency: 5, download_throughput: 2 * 1024, upload_throughput: 2 * 1024}
The settings will match to the following UI component in Chrome:
Were the values for the default profiles might match the values from this post:
**S...
List of Chromium Command Line Switches « Peter Beverloo
An extensive list of command line options when booting Chrome.
This is useful for building a Capybara driver with custom Chrome options.
Yarn: if integrity check won't let you start rails console
I ran into a situation in which I received the yarn integrity check warning when starting the rails console even though everything was up to date and correct versions in use.
TLDR: run spring stop
I tried starting the rails console without switching to the correct node version first and received the yarn integrity warning.
warning Integrity check: System parameters don't match
error Integrity check failed ...
Ruby: required keyword arguments in the pre-2.1 era
Starting with Ruby 2.0 you can define methods with keyword arguments.
In 2.1+ required keyword arguments can be defined by using a colon without default value:
def match(value, ignore:)
# ...
end
To accomplish something similar in ruby 1.8, use:
def match(value, options = {})
ignore = options.fetch(:ignore)
# ...
end
How to avoid raising RestClient exceptions for 4xx or 5xx results
When using RestClient to make an HTTP request, it will raise an exception when receiving a non-successful response.
HTTP status codes like 422 or 403 might be totally expected when talking to APIs, so plastering your code with rescue RestClient::Exception
or similar can feel annoying.
It may not be intuitive, but the readme says you can also pass a block to methods like RestClient.get
or RestClient::Request.execute
. In that case, RestClient will not raise ...
Die Grenzen von SEO: was Suchmaschinenoptimierung nicht ist
Der verlinkte Artikel grenzt präzise ab, welche Aufgaben zur Suchmaschinenoptimierung (SEO) gehören und welche nicht.
Suchmaschinenoptimierung ist eine Querschnittsfunktion: die Arbeit vieler unterschiedlicher Abteilungen hat Einfluss auf den SEO-Erfolg der Firma. In diesem Beitrag versuchen wir deswegen, den Kern von SEO zu definieren.
Don't use migrations to seed default data
Don't insert table rows in a Rails database migration. This will break tests that expect that database to be empty and cause you all sorts of pain.
If you need a place for default application data, use db/seed.rb or put a script into lib/scripts
. It won't run automatically, so add a chore story to Pivotal Tracker as a reminder.
GitHub Actions: Manually running a workflow
To start a workflow manually it must have a trigger called workflow_dispatch
:
---
name: Tests
on:
push:
branches:
- master
pull_request:
branches:
- master
workflow_dispatch:
branches:
- master
In the Actions tab of your repo you can now select a workflow and press "Run Workflow".
GitHub Actions: Retrying a failing step
If you have a flaky command you can use the nick-invision/retry to re-try a failing command, optionally with a timeout:
---
...
jobs:
test:
...
steps:
- name: Run tests
uses: nick-invision/retry@v2
with:
timeout_seconds: 30
max_attempts: 3
command: bundle exec rake spec
Custom error pages in Rails
Basic error pages
To add a few basic styles to the default error pages in Rails, just edit the default templates in public
, e.g. public/404.html
.
A limitation to these default templates is that they're just static files. You cannot use Haml, Rails helpers or your application layout here. If you need Rails to render your error pages, you need the approach below.
Advanced error pages
- Register your own app as the applicatio...
Find an ActiveRecord by any column (useful for Cucumber steps)
The attached patch lets you find a record by a string or number in any column:
User.find_by_anything('carla')
User.find_by_anything('email@domain.de')
User.find_by_anything(10023)
There's also a bang variant that raises ActiveRecord::NotFound
if no record matches the given value:
User.find_by_anything!('carla')
Boolean and binary columns are excluded from the search because that would be crazy.
I recommend copying the attachment to features/support/find_by_anything.rb
, since it is most useful in Cucumber step def...
How to checkout submodules in Gitlab CI
Accessing other repositories in Gitlab CI is not straight forward, since the access rights of the current pipeline might not be sufficient enough.
One approach is to use project access tokens and clone the repositories via HTTPS.
-
Create a project access token for all submodules you want to have access to with the setting
read_repository
- Add the secrets as environment variable to the main project you want to have access to submodules:
- Protected
false
...
- Protected
Git: Show commits that have touched specific text in a file
If you want to find the commits that touched a specific text in a file, use
git log -S 'text in the code' -- path/to/file
If you use tig you may run a similar command to get a navigatable list of affected files:
tig -S'text in the code'
Example
Here is an example, where the move of the convert_number_column_value(value)
method in active record is traced (simplified output):
git log -n 1 --pretty=oneline -S 'convert_number_column_value(value)' -- activerecord/lib/active_record/base.rb
ceb33f84933639d3b6...
Undefined method log for Selenium::WebDriver::Remote::W3C::Bridge
In case your integration tests crash with a message like below, try to upgrade Capybara to a newer version (3.35.3 was good enough). You might encounter this issue when you enabled the w3c option in Selenium.
undefined method `log' for #<Selenium::WebDriver::Remote::W3C::Bridge:0x000055995647ded0>
Your affected code might look similar to this call below and will work after the upgrade again.
Upgrading Capybara with deprecated Integer selectors
Capybara added a deprecation warning in version 3.35.3 (version from 2019) that shows up if your selector is not of type String or Symbol.
Example:
click_link(10) # bad
click_link("10") # good
You might encounter this error e.g. in a pagination step or similar where you want to click on numbers. To figure out where this deprecation warning comes from try to run the tests with a step output.
bundle exec parallel_cucumber --test-options "--format=pretty" feature
The deprecation message looks like following:
Locator In...
Geordi 6.0.0 released
6.0.0 2021-06-02
Compatible changes
-
geordi commit
will continue even if one of the given projects is inaccessible. It will only fail if no stories could be found at all.
Breaking changes
- Removed VNC test browser support for integration tests – Headless Chrome has
matured and is almost a drop-in replacement. Also, key binding issues have
increased with VNC and recent Linux.- Please use a headless Chrome setup https://makandracards.com/makandra/492109-capybara-running-tests-with-headless-chrome.
- You might also ...
PSA: Chrome and Firefox do not always clear session cookies on exit
Cookies without an expiration timestamp are called "session cookies". [1] They should only be kept until the end of the browsing session.
However, when Chrome or Firefox are configured to reopen tabs from last time upon start, they will keep session cookies when closing the browser. This even applies to tabs that were closed before shutting down the browser.
This is by design in Chrome and [Firefox](https://bugzilla.mozilla.org/buglist.cgi?bug_id=337551,345830,358042,362212,36...
Chromedriver: Disabling the w3c option might break your integration tests with Chrome 91
We recently noticed issues with Chrome 75+ when having the w3c
option enabled within the Selenium webdriver. It looks like recent Selenium versions don't have any issues with the w3c interface anymore. And starting with Chrome 91 this fix might cause unexpected issues, so you should try to enabled this option again or just remove the following line from you configuration:
options.add_option('w3c', false)
Background: Setting the w3c
option t...
RubyMine / IntelliJ: How to increase UI and fonts for presentations
When giving a presentation where you do some coding, the font size you usually use is probably a bit too small and makes code hard to read for users on smaller screens or low-bandwidth connections when the image quality is lower.
Here are two solutions.
Presentation Mode
RubyMine offers a "Presentation Mode" which you can use. Simply navigate to View → Appearance → Enter Presentation Mode to enable it.
This will increase your code editor's font size as well as your UI and works nicely when sharing a single file.
However, some control...