I have to maintain a Ruby script, which requires some libs I don't have locally and which won't work in my environment. Nevertheless I want to spec some methods in this script so that I can change them easily.
Is there an option to stub some of the require statements in the script I want to test so that it can be loaded by rspec and the spec can be executed within my environment?
Example (old_script.rb):
require "incompatible_lib"
class Script
def some_other_stuff
...
end
def add(a,b)
a+b
end
end
How can I write a test to check the add function without splitting the "old_Script.rb" file and without providing the incompatible_lib I don't have?
Instead of stubbing require which is "inherited" from Kernel, you could do this:
Create a dummy incompatible_lib.rb file somewhere that is not in your $LOAD_PATH. I.e., if this is a Ruby application (not Rails), don't put it in lib/ nor spec/.
You can do this a number of ways, but I'll tell you one method: in your spec file which tests Script, modify $LOAD_PATH to include the parent directory of your dummy incompatible_lib.rb.
Ordering is very important -- next you will include script.rb (the file which defines Script).
This will get you around the issue and allow you test test the add method.
Once you've successfully tested Script, I would highly recommend refactoring it so that you don't have to do this technique, which is a hack, IMHO.
Thanks, I also thought about the option of adding the files, but finally hacked the require itself within the test case:
module Kernel
alias :old_require :require
def require(path)
old_require(path) unless LIBS_TO_SKIP.include?(path)
end
end
I know that this is an ugly hack but as this is legacy code executed on a modified ruby compiler I can't easily get these libs running and it's sufficient to let me test my modifications...
Related
Yes, I know I can just use load instead of require. But that is not a good solution for my use case:
When the app boots, it requires a config file. Each environment has its own config. The config sets constants.
When the app boots, only one environment is required. However, during testing, it loads config files multiple times to make sure there are no syntax errors.
In the testing environment, the same config file may be loaded more than once. But I don't want to change the require to load because every time the a spec runs, it reloads the config. This should be done via require, because if the config has already been loaded, it raises already initialized constant warnings.
The cleanest solution I can see is to manually reset the require flag for the config file after any config spec.
Is there a way to do that in Ruby?
Edit: adding code.
When the app boots it calls the init file:
init.rb:
require "./config/environments/#{ ENV[ 'RACK_ENV' ]}.rb"
config/environments/test.rb:
APP_SETTING = :foo
config/environments/production.rb:
APP_SETTING = :bar
spec/models/config.rb: # It's not a model spec...
describe 'Config' do
specify do
load './config/environments/test.rb'
end
specify do
load './config/environments/production.rb'
end
Yes it can be done. You must know the path to the files that you want to reload. There is a special variable $LOADED_FEATURES which stores what has been loaded, and is used by require to decide whether to load a file when it is requested again.
Here I am assuming that the files you want to re-require all have the unique path /myapp/config/ in their name. But hopefully you can see that this would work for any rule about the path name you can code.
$LOADED_FEATURES.reject! { |path| path =~ /\/myapp\/config\// }
And that's it . . .
Some caveats:
require does not store or follow any kind of dependency tree, to know what it "should" have loaded. So you need to ensure the full chain of requires starting with the require command you run in the spec to re-load the config, and including everything you need to be loaded, is covered by the removed paths.
This will not unload class definitions or constants, but simply re-load the files. In fact that is literally what require does, it just calls load internally. So all the warning messages about re-defining constants will also need to be handled by un-defining the constants you expect to see defined in the files.
There is probably a design of your config and specs that avoids the need to do this.
if you really want to do this, here's one approach that doesn't leak into your test process. Fork a process for every config file you want to test, communicate the status back to the test process via IO.pipe and fail/succeed the test based on the result.
You can go as crazy as you want with the stuff you send down the pipe...
Here's some quick and dirty example to show you what I mean.
a config
# foo.rb
FOO = "from foo"
another config
# bar.rb
FOO = "from bar"
some faulty config
# witherror.rb
asdf
and your "test"
# yourtest.rb
def load_config(writer, config_file)
fork do
begin
require_relative config_file
writer.write "success: #{FOO}\n"
rescue
writer.write "fail: #{$!.message}\n"
end
writer.close
exit # maybe this is even enough to NOT make it run your other tests...
end
end
rd, writer = IO.pipe
load_config(writer, "foo.rb")
load_config(writer, "bar.rb")
load_config(writer, "witherror.rb")
writer.close
puts rd.read
puts rd.read
puts rd.read
puts FOO
The output is:
success: from foo
success: from bar
fail: undefined local variable or method `asdf' for main:Object
yourtest.rb:24:in `<main>': uninitialized constant FOO (NameError)
as you can see, the FOO constant doesn't leak into your test process etc.
Of course you're only through half way because there's more to it like, making sure only one process runs the test etc.
Frankly, I don't think this is a good idea, no matter what approach you chose because you'll open a can of worms and imho there's no really clean way to do this.
In my Rails application I have a file sample_data.rb inside /lib/tasks as well as a bunch of test files inside my /spec directory.
All these files often share common functionality such as:
def random_address
[Faker::Address.street_address, Faker::Address.city].join("\n")
end
Where should I put those helper functions? Is there some sort of convention on this?
Thanks for any help!
You could create a static class, with static functions. That would look something like this:
class HelperFunctions
def self.random_address
[Faker::Address.street_address, Faker::Address.city].join("\n")
end
def self.otherFunction
end
end
Then, all you would need to do is:
include your helper class in the file you want to use
execute it like:
HelperFunctions::random_address(anyParametersYouMightHave)
When doing this, make sure you include any dependencies in your HelperFunctions class.
If you're sure it's rake only specific, you also can add in directly in RAILS_ROOT/Rakefile (that's probably not the case for the example you use).
I use this to simplify rake's invoke syntax :
#!/usr/bin/env rake
# Add your own tasks in files placed in lib/tasks ending in .rake,
# for example lib/tasks/capistrano.rake, and they will automatically be available to Rake.
require File.expand_path('../config/application', __FILE__)
def invoke( task_name )
Rake::Task[ task_name ].invoke
end
MyApp::Application.load_tasks
That way, I can use invoke "my_namespace:my_task" in rake tasks instead of Rake::Task[ "my_namespace:my_task" ].invoke.
You share methods in a module, and you place such a module inside the lib folder.
Something like lib/fake_data.rb containing
module FakeData
def random_address
[Faker::Address.street_address, Faker::Address.city].join("\n")
end
module_function
end
and inside your rake task just require the module, and call FakeData.random_address.
But, if it is like a seed you need to do every time you run your tests, you should consider adding this to your general before all.
E.g. my spec_helper looks like this:
# Requires supporting ruby files with custom matchers and macros, etc,
# in spec/support/ and its subdirectories.
Dir[Rails.root.join("spec/support/**/*.rb")].each { |f| require f }
RSpec.configure do |config|
config.use_transactional_fixtures = true
config.infer_base_class_for_anonymous_controllers = false
config.order = "random"
include SetupSupport
config.before(:all) do
load_db_seed
end
end
and the module SetupSupport is defined in spec/support/setup_support.rb and looks as follows:
module SetupSupport
def load_db_seed
load(File.join(Rails.root, 'db', 'seeds.rb'))
end
end
Not sure if you need to load the seeds, or are already doing this, but this is the ideal spot to also generate needed fake data.
Note that my setup support class is defined in spec/support because the code is only relevant to my specs, I have no rake task also needing the same code.
I'd like to test class and gem loading. Have a look at the following stupid test case:
require 'rubygems'
require 'shoulda'
class SimpleTest < Test::Unit::TestCase
context 'This test' do
should 'first load something' do
require 'bundler'
assert Object.const_defined? :Bundler
end
should 'second have it reset again' do
assert !Object.const_defined?(:Bundler)
end
teardown do
# This works, but is tedious and unclean
#Object.send :remove_const, :Bundler rescue nil
# Instead I want something like this ;)
magic_reset
end
end
end
How about creating a subclass of Test::Unit::TestCase which runs the test method in a forked process?
class ForkingTestCase < Test::Unit::TestCase
def run(...)
fork do
super.run(...)
# somehow communicate the result back to the parent process
# this is the hard part
end
end
end
If this can be implemented, it should then just be a matter of changing the base class of your test case.
AFAIK, you cannot unload a file that you have loaded. You need to start a separate Ruby process for every test. (Or a separate Ruby instance if you are running on a Ruby implementation which supports multiple instances in the same process.)
Try using Kernel#load with wrap set to true:
load(filename, wrap=false) → true
Loads and executes the Ruby program in the file filename. If the
filename does not resolve to an absolute path, the file is searched
for in the library directories listed in $:. If the optional wrap
parameter is true, the loaded script will be executed under an
anonymous module, protecting the calling program’s global namespace.
In no circumstance will any local variables in the loaded file be
propagated to the loading environment.
each time you want to do a test of bundler, load it into a new anonymous module, do your tests on the bundler class within that module, and then go onto your next test.
If your code refers to the Bundler constant, then you'd have to set and unset that constant, though.
I haven't tried it myself, but can't see why it wouldn't work.
Try keeping track of what constants were defined before your tests started, and what constants are defined after your test finished, and remove the constants that were defined during the test.
I guess this isn't so much telling you how to call magic_reset as how to implement magic_reset.
Is there a shorter way to require a file located in the same directory (as the script being executed)?
require File.expand_path(File.dirname(__FILE__) + '/some_other_script')
I read that require "my_script" and require "./my_script" will actually load the script twice (ruby will not recognize that it is actually the same script), and this is the reason why File.expand_path is recommended: if it is used every time the script is required, then it will only be loaded once.
It seems weird to me that a concise language like Ruby does not seem to have a shorter solution. For example, python simply has this:
import .some_other_module_in_the_same_directory
I guess I could monkey-patch require... but that's just evil! ;-)
Since ruby 1.9 you can use require_relative.
Check the latest doc for require_relative or another version of the Core API.
Just require filename.
Yes, it will import it twice if you specify it as filename and ./filename, so don't do that. You're not specifying the .rb, so don't specify the path. I usually put the bulk of my application logic into a file in lib, and then have a script in bin that looks something like this:
#!/usr/bin/env ruby
$: << File.join(File.dirname(__FILE__), "/../lib")
require 'app.rb'
App.new.run(ARGV)
Another advantage is that I find it easier to do unit testing if the loading the application logic doesn't automatically start executing it.
The above will work even when you're running the script from some other directory.
However, inside the same directory the shorter forms you refer to work as expected and at least for ruby 1.9 won't result in a double-require.
testa.rb
puts "start test A"
require 'testb'
require './testb'
puts "finish test A"
testb.rb
puts "start test B"
puts "finish test B"
running 'ruby testa.rb' will result in:
start test A
start test B
finish test B
finish test A
However, the longer form will work even from another directory (eg. ruby somedir/script.rb)
Put this in a standard library directory (somewhere that's already in your default loadpath $:):
# push-loadpath.rb
if caller.first
$: << File.expand_path(File.dirname(caller.first))
end
Then, this should work
% ls /path/to/
bin.rb lib1.rb lib2.rb #...
% cat /path/to/bin.rb
load 'push-loadpath.rb'
require 'lib1'
require 'lib2'
#...
caller gives you access to the current callstack, and tells you what file and where, so push-loadpath.rb uses that to add the file that load'd it to the loadpath.
Note that you should load the file, rather than require it, so the body can be invoked multiple times (once for each time you want to alter the loadpath).
Alternately, you could wrap the body in a method,
# push-loadpath.rb
def push_loadpath
$: << File.expand_path(File.dirname(caller.first))
end
This would allow you to require it, and use it this way:
% ls /path/to/
bin.rb lib1.rb lib2.rb #...
% cat /path/to/bin.rb
require 'push-loadpath'
push_loadpath
require 'lib1'
require 'lib2'
#...
[I'm just starting with Ruby, but "no question is ever too newbie," so I trudge onwards...]
Every tutorial and book I see goes from Ruby with the interactive shell to Ruby on Rails. I'm not doing Rails (yet), but I don't want to use the interactive shell. I have a class file (first_class.rb) and a Main (main.rb). If I run the main.rb, I of course get the uninitialized constant FirstClass. How do I tell ruby about the first_class.rb?
The easiest way is to put them both in the same file.
However you can also use require, e.g.:
require 'first_class'
You can also use autoload as follows:
autoload :FirstClass, 'first_class'
This code will automatically load first_class.rb as soon as FirstClass is used. Note, however, that the current implementations of autoload are not thread safe (see http://www.ruby-forum.com/topic/174036).
There's another point worth noting: you wouldn't typically use a main file in ruby. If you're writing a command line tool, standard practice would be to place the tool in a bin subdirectory. For normal one-off scripts the main idiom is:
if __FILE__ == $0
# main does here
# `__FILE__` contains the name of the file the statement is contained in
# `$0` contains the name of the script called by the interpreter
#
# if the file was `required`, i.e. is being used as a library
# the code isn't executed.
# if the file is being passed as an argument to the interpreter, it is.
end