Test that a form field is visible with Cucumber/Capybara

Spreewald now comes with a step that tests if a form field is visible:

Then the "Due date" field should be visible
But the "Author" field should not be visible

The step works by looking up the field for the given label, then checks if that field is hidden via CSS (or Javascript).

It is not currently tested if the label is visible or hidden. For this see: [Check that an element is visible or hidden via CSS with Cucumber/Capybara](https://makandracards.com/makandra/1049-check-that-an-elem...

Consul: Querying a power that might be nil

Consul 0.6.1+ gives your Power class a number of static methods that behave neutrally in case Power.current is nil. This allows you to create authorization-aware models that still work when there is no user at the end of a web browser, e.g. on the console, during tests or during batch processes.


You will often want to access Power.current from another model, to e.g. iterate through the list of accessible users:

class UserReport

  def data
    Power.current.users.c...

Memcache: Your cache node may degenerate over time, check your settings

We recently had a problem on a Memcache cluster, where one of the servers showed a significantly worse cache hit rate and a lot more evictions.

It turned out that the only reason was that the server was running for a few months longer than the others. Some investigation showed this to be a known problem with Memcache: Once your cache gets full, it might be "hardwired" for your specific usage patterns. If those change (and you for example start to store larger values), memory is no longer allocated optimally, in extreme cases Memcache might ...

How to update a single gem conservatively

The problem

Calling bundle update GEMNAME will update a lot more gems than you think. E.g. when you do this:

bundle update cucumber-rails

... you might think this will only update cucumber-rails. But it actually updates cucumber-rails and all of its dependencies. This will explode in your face when one of these dependencies release a new version with breaking API changes. Which is all the time.

In the example above updating cucumber-rails will give you Capybara 2.0 (because capybara is a dependency of `cucumber-rail...

Running "bundle update" will update all gems without constraints

Calling bundle update (without arguments) updates all your gems at once. Given that many gems don't care about stable APIs, this might break your application in a million ways.

To stay sane, update your gems using the applicable way below:

Projects in active development

Update the entire bundle regularily (e.g. once a week). This ensures that your libraries are up-to-date while it's easy to spot major version bumps which may break the app.

Projects that have not been updated in a while

  1. [Update a single gem conservatively](htt...

Error: "sylogd: /var/log/authlog : no such file or directory" but the file exists

If you get a message like this:

Jan 21 13:42:38 foobar syslogd: /var/log/authlog : no such file or directory

But you are sure the file exists and it have the correct permissions:

# example for Solaris 9
-rw-r--r-- 1 root sys 8,0K 21. Jan 13:51 /var/log/authlog

Then you perhaps have a trailing whitespace after /var/log/authlog in the /etc/syslog.conf.

Note: Use TAB to separate log components from log file names in Solaris. Because spaces do not work.

Using Apache Benchmark (ab) on sites with authentication

Apache HTTP server benchmarking tool (ab) is a nice tool to test performance on sites delivered by HTTP. If the site you're about to test is placed behind a login, follow these steps to successfully use ab on it.

  1. Open the site to test in the browser of your choice. Do not login yet.
  2. Use developer tools to show all cookies used by the site. (Chrome: Ctrl+Shift+i, open the 'Resources' tab and click on the site below 'Cookies' on the left. Firefox: Right-click on the site, open 'We...

Compare two jQuery objects for equality

Every time you call $(...) jQuery will create a new object. Because of this, comparing two jQuery collections with == will never return true, even when they are wrapping the same native DOM elements:

$('body') == $('body') // false

In order to test if two jQuery objects refer to the same native DOM elements, use is:

var $a = $('body');
var $b = $('body');
$a.is($b); // true

Jasmine equality matcher for jQuery

See [here](/makandra/34925-jasmine-testing-complex-types-for-e...

The Shapes of CSS

Examples how to create dozens of shapes using pure CSS and a single HTML element.

Git blame: How to ignore white-space modifications

When doing a git blame, git will blame the person who added or removed white space in a line (e.g. by indenting), not the person who originally wrote the code.

Say git blame -w to ignore such white-space changes. You want this. \
Note that you can also use it when diffing: git diff -w.

Example

Consider this method, created by a user in commit d47bf443:

def hello
  'world'
end

^

$ git blame foo
d47bf443 (Arne Hartherz 2012-12-19 14:44:38 +0100 1) def hello
d47bf443 (Arne Hartherz 2012-12-19 14:44:38 +0100 2...

randym/axlsx ยท GitHub

Axlsx is an incredible gem to generate "Office Open XML" spreadsheet files (XLSX). Does not break on large spreadsheets and supports a ton of features like graphs.

API looks mature and existing code is easy to migrate when coming from the spreadsheet gem.
The documentation of some methods is a bit out of date, but you'll find your way around the gem's code.

No support for reading files, however. :( If you want to open XLSX spreadsheets (for example to confirm your output in tests), you can use [roo](h...

RSpec: Defining helper methods for an example group

You can define methods in any example group using Ruby's def keyword or define_method method:

describe "example" do
  def sum(a, b)
    a + b
  end

  it "has access to methods defined in its group" do
    expect(sum(3, 4)).to be(7)
  end
end

The helper method is also available to groups nested within that group. The helper method is not available to parent or sibling groups.

Global helpers

To define helpers for all specs (or all specs of a type), [define it in a module](https://rspec.info/features/3-12/rspec-core/help...

Understanding database cleaning strategies in tests

TLDR: In tests you need to clean out the database before each example. Use :transaction where possible. Use :deletion for Selenium features or when you have a lot of MyISAM tables.

Understanding database cleaning

You want to clean out your test database after each test, so the next test can start from a blank database. To do so you have three options:

  • Wrap each test in a transaction which is rolled back when you're done (through DatabaseCleaner.strategy = :transaction or `config.use_transactional_fi...

Git: In an (interactive) rebase, find out which commit you are currently working on (until version < 1.7.9.5)

When you are using git rebase and are currently editing a commit (due to a conflict, for example), you may want to know the current commit. [1]\
Luckily, there is lots of useful stuff in the .git directory.

Commit hash that you are currently applying

cat .git/rebase-merge/stopped-sha

Useful if you want to inspect the original commit for its changes, for example like:

git show `cat .git/rebase-merge/stopped-sha`

Current commit's message

cat .git/rebase-merge/message

In case you forgot what the changes are suppo...

jquery-timing - a jQuery plugin you should know about

jquery-timing is a very useful jquery plugin that helps to remove lots of nested anonymous functions. It's API provides you some methods that help you to write readable and understandable method chains. See yourself:

Example

// before
$('.some').show().children().doThat();
window.setTimeout(function(){
  $('some').children().doSomething().hide(function() {
    window.setTimeout(function() {
      otherStuffToDo();
    }, 1000);
  });
}, 500);

// after
$('.some').s...

How to provoke Selenium focus issues in parallel test processes

As attachments to this card you will find a Cucumber feature and supplementing step definition that you can use to provoke Selenium focus issues that only occur when two focus-sensitive Selenium scenarios run at the same time (probably with parallel_tests). This can help you to detect and fix flickering integration tests.

The attached feature works by going to your root_path and focusing a random form element every 5...

Analyse TCP/UDP traffic with netcat

Sometimes you want to see what data you get through a TCP or UDP connection.
For example, you want to know how a HTTP Request look like.

It's very easy with netcat.

Example to listen on port 80 and the output gets to stdout.

sudo nc -kl 80

It's also possible write it into a file:

sudo nc -kl 80 > output.txt

If you use Ports higher than 1000 you don't need to be root (sudo).

Custom bash autocompletion

The bash offers control over the behavior of autocompletion.

The most primitive example is this (just run it in your bash; if you want it available everywhere, put the complete ... line into your .bashrc):

> complete -W "list of all words for an automatic completion" command_to_be_completed
> command_to_be_completed a<TAB>
all an automatic

With complete you define how the specified command shall be completed. For basic needs, -W (as in "word list") should be enough, but you may also specify a function, a glob patte...

How to test if an element has scrollbars with JavaScript (Cucumber step inside)

The basic idea is pretty simple: an element's height is accessible via the offsetHeight property, its drawn height via scrollHeight -- if they are not the same, the browser shows scrollbars.

var hasScrollbars = element.scrollHeight != element.offsetHeight;

So, in order to say something like...

Then the element "#dialog_content" should not have scrollbars

... you can use this step (only for Selenium scenarios):

Then /^the element "([^\"]+)" should( not)? have scrollbars$/ do |selector, no_scrollbars|
  scroll_heig...

How to find out the currently focused DOM element with JavaScript

This works in all relevant browsers:

document.activeElement

You can use this in your Selenium steps, for example, to assert that a form field is or is not focused.

Performance analysis of MySQL's FULLTEXT indexes and LIKE queries for full text search

When searching for text in a MySQL table, you have two choices:

  • The LIKE operator
  • FULLTEXT indexes (which currently only work on MyISAM tables, but will one day work on InnoDB tables. The workaround right now is to extract your search text to a separate MyISAM table, so your main table can remain InnoDB.)

I always wondered how those two methods would scale as the number of records incr...

Custom error pages in Rails

Static 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.

Dynamic error pages

  1. Register your own app as the applicatio...

Cronjobs: "Craken" is dead, long live "Whenever"

Our old solution for cronjobs, the "craken" plugin, is no longer maintained and does not work on Rails 3.2+.

We will instead use the whenever gem.

"Whenever" works just like "craken", by putting your rake tasks into the server's cron table. Everything seems to work just like we need it.

Installation for new projects

  1. Add "whenever" to your Gemfile:

     group :deploy do
       gem 'whenever', require: false
     end
    
  2. Add it to your config/deploy.rb:
    ...