When you develop a gem and you have a Gemfile in your project directory, you might be surprised that your gem dependencies aren't already required in your specs. Here is some info that should help you out:

• Bundler actually doesn't automatically require anything. You need to call Bundler.require(:default, :your_custom_group1, ...) for that. The reason why you never had to write this line is that Rails does this for you when it boots the environment.
• That also means that if you have an embedded Rails app in your spec folder (like [h...

While deploying an Ruby update to an old application these days, we encountered the following misleading error:

*** [err :: some-host.makandra.de] You are trying to install in deployment mode after changing
*** [err :: some-host.makandra.de] your Gemfile. Run `bundle install` elsewhere and add the
*** [err :: some-host.makandra.de] updated Gemfile.lock to version control.
*** [err :: some-host.makandra.de] 
*** [err :: some-host.makandra.de] You have deleted from the Gemfile:
*** [err :: some-host.makandra.de] *

We found out a newe...

So you're getting an error like this:

undefined method `activate_bin_path' for Gem:Module (NoMethodError)

Here is what happened:

• You installed a recent version of Rubygems
• You installed some gems that install a binary (like bundle, rake or rails) with code that only works with modern Rubygems versions
• You downgraded Rubygems to an older versions, which doesn't change any binaries
• When calling binaries with the old Rubygems version, it cannot process the line Gem.activate_pin_path(...) that was written out by th...

After updating your RubyGems, you will probably not be able to run Capistrano any more, but receive an error similar to this:
can't activate net-ssh (= 2.0.22) for [], already activated net-ssh-2.1.0 for [] (Gem::LoadError)

If you have Bundler installed, you can use bundle exec to avoid this problem as follows:

Create a gemfile at ~/.capistrano/Gemfile (or at some other sensible place), that only contains these 2 lines:
source 'http://rubygems.org'
gem 'capistrano'
gem 'capistrano-ext' # You need this for multistag...

Debugging your integration tests, that run a headless Chrome inside a docker image, is tricky.

In many cases you can connect your Chrome to a remote docker container like docker-selenium, which should be the preferred way when you try to inspect a page within your integration test.

Otherwise you might be able to start your docker container with --net=host and access your local chromedriver in the host address space host.docker.internal.

If both options above don't work for you here is a...

Note

Use yarn dedupe in Yarn v2+: https://yarnpkg.com/cli/dedupe

This package only works with Yarn v1. Yarn v2 supports package deduplication natively!

A duplicate package is when two dependencies are resolved to a different version, even when a single version matches the range specified in the dependencies. See the Deduplication strategies section for a few examples.

Yarn is stupid, so it can happen that there are several version of the same package in your bundle, although one would fulf...

If you use a newer SSH key generated with the ED25519 algorithm instead of RSA (see Create a new SSH key pair), the deployment with Capistrano may fail with the following message:

The deploy has failed with an error: unsupported key type `ssh-ed25519'
net-ssh requires the following gems for ed25519 support:
 * ed25519 (>= 1.2, < 2.0)
 * bcrypt_pbkdf (>= 1.0, < 2.0)
See https://github.com/net-ssh/net-ssh/issues/565 for more information
Gem::LoadError : "ed25519 i...

On the Rails console, assigning an object to a variable can lead to this strange error (without stacktrace):

irb > recipient = Recipient.find(123)
Traceback (most recent call last):
TypeError (nil can't be coerced into Integer)
irb > recipient
#<Recipient ...

The error is only in the output – the assignment is working. It only occurs when using the --nomultiline option, and thus [only with IRB 1.2.0+ and before Ruby 3](https://github.com/makandra/geordi/blob...

There is a new card about how to do this with the new AWS Command Line Interface

At first you need the IAM Cli Tools.
-------------------------------------------------------------------------------------------------------------...

In order to monitor a Rake task using God your Rake file must write a file with its process ID (PID) to a path determined by God. This way God can check whether the Rake process is still alive.

Here is how to do this: In your God config, call the Rake task with an environment variable PIDFILE. This variable should equal the PID file path desired by God:

God.watch do |w|
  w.dir = "#{rails_root}"
  w.name = "my_task"
  w.interval = 10.seconds
  w.pid_file = "#{rails_root}/tmp/pids/#{w.name}...

Geordi uses parallel_tests if available for running the test suite. To debug an application it is very unhandy to have multiple processes as your terminal I/O will not work as expected once a breakpoint is hit.

Even parallel_tests support an option to enable a single process run, it is not possible to pass this option through geordi. But you can set the number of processes via ENV variable manually:

PARALLEL_TEST_PROCESSORS=1 bundle exec geordi cucu...

Geordi 1.0 features a command line application geordi, that holds most of Geordi's previous commands.

New features

• command help and usage examples right within geordi (geordi help and geordi help <command>)

• quick command access: type just the first few letters of a command, e.g. geordi rs or geordi dev[server]

• command dependencies, e.g. geordi rspec invokes geordi bundle-install (which bundles only if needed)

• no cluttered /usr/bin, but all commands in one handy tool

• template for easily adding new...

Sometimes you want to load code on demand. For instance, when a a large library is only used on a single screen, this library should only be loaded for that screen. It should not blow up the bundle size for all screens.

You can load code on demand by using import() as a function (with parentheses) instead of using it as a keyword import (without parentheses). The import() function returns a promise with the exported variables:

let exports = await import('large-library')

console.log("A named export is ", exports.exportedName)
c...

Aruba is an extension to Cucumber that helps integration-testing command line tools.

When your tests involve a Rails test application, your tool's Bundler environment will shadow that of the test application. To fix this, just call unset_bundler_env_vars in a Cucumber Before block.

Previously suggested solution

Put the snippet below into your tool's features/support/env.rb -- now any command run through Aruba (e.g. via #run_simple) will have a clean Bundler envir...

Use bundler > 1.15 to fix Gem::LOADED_SPECS_MUTEX (NameError).

Given the following project:

ruby -v
ruby 1.8.7

bundler -v
Bundler version 1.13.7

gem -v
1.8.30

rails -v
Rails 3.2.22.1

Running specs or features resulted in:

uninitialized constant Gem::LOADED_SPECS_MUTEX (NameError)

The previous settings described in Maximum version of Rubygems and Bundler for Ruby 1.8.7 and Rails 2.3 (even the rails version was rails 3.2 and not 2.3) seems not to work here, so I used (also described in the ca...

You're better off using debugger-ruby_core_source:

gem install debugger-ruby_core_source

If you can't do this, try the following.

Here is how to fix the following error when installing the debugger gem fails:

Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension

Note: The following example is for a project using Ruby 1.9.3-p448 -- adjust accordingly for your project.

1. Fetch the source for your Ruby version, if you do not yet have it:

   rvm fetch ruby-1.9.3-p448
   

2. Install t...

1. Install Ruby from the Ubuntu repository: sudo apt-get install ruby ruby-dev \
   ruby is the meta package. If you want to explicitly install 1.8 or 1.9, install ruby1.8 or ruby1.9 instead (the same applies for ruby-dev).
2. Do not install RubyGems from the repository but install the version from the webpage instead.
3. Get Bundler: sudo gem install bundler

Rails and other gems for a project should now be installed via bundle install from the...

It sometimes happen that a database dump, that would want to insert into your development database, does not match the current schema of the database. This often happens when you have an old dump, but your current setup is up to date with the the master.

Hint: In most cases it is sufficient to delete and recreate the local database in order to import the dump. If any problems occur, proceed as follows:

1. Figure out the original migration status of the dumpfile

• Convert your dump to plaintext: `pg_restore -f some.dump > some.dump....

spring ...

The most obvious way to use spring is to call it explicitly:

spring rails console
spring rake db:migrate

Binstubs

Binstubs are wrapper scripts around executables. In Rails they live inside bin/. If you run spring binstub --all, your binstubs will be using Spring.

bin/rails console
bin/rake db:migrate

bundle exec rails ...

Bundle exec is inconsistent when it comes to spring. Some commands will use it, some won't.

bundle exec rails console # starts Spring...

If you have a fully functional CI pipeline but no CD, you might find yourself frequently waiting for CI (with "merge after pipeline succeeds") just to perform the deployment.

The following command waits for the next commit that lands on the current branch (should be main or similar) and proceeds to deploy staging afterwards:

alias await-deployment='watch -g git pull && bundle exec cap staging deploy'

Note

Use at your own risk.
You could be deploying code from someone else that was pushed to the same branch in the meantime.

Ruby's mathn library changes Fixnum division to work with exact Rationals, so

2 / 3 => 0
2 / 3 * 3  => 0

require 'mathn'
2 / 3 => Rational(2,3)
2 / 3 * 3 => 2

While this might sometimes be quite neat, it's a nightmare if this gets required by some gem that suddenly redefines integer division across your whole project. Known culprits are the otherwise excellent distribution and [GetText](https://g...

I just ran into this deployment error after switching from the asset pipeline to webpack:

01:05 deploy:assets:precompile
      01 bundle exec rake assets:precompile
      01 Compiling...
      01 Compilation failed:
      01 yarn run v1.22.5
      01 error Command "webpack" not found.
rake stderr: Nothing written

The problem is not related to the "webpack" dependency. You probably just forgot to add a binstub to run "yarn install":

Add these lines to "bin/ya...

There is no reason to leave trailing whitespace characters in your project's files, so don't add any.

A git diff --check will tell you if there are any and you should not commit when you see them. So go ahead and switch your editor/IDE to automatically remove them for you.
Below are a few instructions on how to get them removed by your favorite IDE or editor.

Note that except for RubyMine, the following changes will remove trailing white-space on all lines, not only those that you changed.
While this should not be a problem if your proje...

Note that you cannot currently use Ruby 1.9.2 with Rails 2 applications that use RSpec, so don't upgrade if that is your setup. The rspec-rails gem has a fatal bug that was only fixed for rspec-rails-2.x, which only supports Rails 3. There is no fix for the rspec-rails-1.3.x series of the gem which supports Rails 2.

Anyway, here are upgrade instructions if you only work with Rails 3 or don't use RSpec. You will lose all your gems in the process, but you can get them back easily if you h...