So, I have a module in my ruby code which looks something like this:
module MathStuff
class Integer
def least_factor
# implementation code
end
end
end
and I have some RSpec tests in which I would like to test that my Integer#least_factor method works as expected. we'll say that the tests are in the same file for simplicity. The tests look something like this:
describe MathStuff do
describe '#least_factor' do
it 'returns the least prime factor' do
expect(50.least_factor).to eq 2
end
end
end
Unfortunately, when I run the tests, I get an error like this:
NoMethodError:
undefined method `least_factor' for 50:Fixnum
Please let me know if you know how to include the MathStuff::Integer class for testing.
Note: just for clarification, I am actually trying to open up the Ruby Integer class here and add methods to it.
Your code should look like:
describe MathStuff::Integer do
describe '#least_factor' do
it 'returns the least prime factor' do
expect(MathStuff::Integer.new.least_factor).to eq 2
end
end
end
But you're calling 50.least_factor and 50 is a Fixnum object, not your MathStuff::Integer and it doesn't have that method defined.
Before the addition of refinements in Ruby 2.1 (and experimental support in 2.0), you couldn't limit the scope of a monkeypatch like this to a particular context (i.e. a module).
But the reason your example doesn't work is that defining an Integer class under the Mathstuff module creates a new class which has nothing to do with the Integer core class. The only way to override the core class is to open the class at the top level (not within a module).
I usually put core extensions in a lib/core_ext subdirectory, named after the class they are patching, in your case lib/core_ext/integer.rb.
Simple but not recomended way:
require "rspec"
class Integer
def plus_one
self + 1
end
end
describe 'MathStuff' do
describe '#plus_one' do
it 'should be' do
expect(50.plus_one).to eq 51
end
end
end
$ rspec test.rb
.
Finished in 0.01562 seconds
1 example, 0 failures
Related
I am trying to write a class in my code to wrap some of the RSpec calls. However, whenever I try to access rspec things, my class simply doesn't see the methods.
I have the following file defined in spec/support/helper.rb
require 'rspec/mocks/standalone'
module A
class Helper
def wrap_expect(dbl, func, args, ret)
expect(dbl).to receive(func).with(args).and_return(ret)
end
end
end
I get a NoMethodError: undefined method 'expect', despite requiring the correct module. Note that if I put calls to rspec functions before the module, everything is found correctly.
I've tried adding the following like to my spec_helper.rb:
config.requires << 'rspec/mocks/standalone'
But to no avail.
I managed to use class variables in my class and passing the functions through from the global context, but that solution seems quite extreme. Also I was able to pass in the test context itself and storing it, but I'd rather not have to do that either.
expect functions by default is associated with only rspec-core methods like it before . If you need to have expect inside a method, you can try adding the Rspec matcher class in the helper file.
include RSpec::Matchers
that error because the self which call expect is not the current rspec context RSpec::ExampleGroups, you could check by log the self
module A
class Helper
def wrap_expect(dbl, func, args, ret)
puts self
expect(dbl).to receive(func).with(args).and_return(ret)
end
end
end
# test case
A::Helper.new.wrap_expect(...) # log self: A::Helper
so obviously, A::Helper does not support expect
now you have 2 options to build a helper: (1) a module or (2) a class which init with the current context of test cases:
(1)
module WrapHelper
def wrap_expect(...)
puts self # RSpec::ExampleGroups::...
expect(...).to receive(...)...
end
end
# test case
RSpec.describe StackOverFlow, type: :model do
include WrapHelper
it "...." do
wrap_expect(...) # call directly
end
end
(2)
class WrapHelper
def initialize(spec)
#spec = spec
end
def wrap_expect(...)
puts #spec # RSpec::ExampleGroups::...
#spec.expect(...).to #spec.receive(...)...
end
end
# test case
RSpec.describe StackOverFlow, type: :model do
let!(:helper) {WrapHelper.new(self)}
it "...." do
helper.wrap_expect(...)
end
end
I am trying to unit test a Plain Old Ruby Object that has a method which calls a class method on a Rails model. The Rails app is quite large (10s of seconds to load) so I'd prefer to avoid loading all of Rails to do my unit test which should run in under 1s.
Example:
class Foo
def bar
SomeRailsModel.quxo(3)
end
end
RSpec.describe Foo do
let(:instance) { Foo.new }
it 'calls quxo on SomeRailsModel' do
expect(SomeRailsModel).to receive(:quxo)
instance.bar
end
end
The problem here is that I need to require 'rails_helper' to load up Rails in order for app/models/some_rails_model to be available. This leads to slow unit tests due to Rails dependency.
I've tried defining the constant locally and then using regular spec_helper which kind of works.
Example:
RSpec.describe Foo do
let(:instance) { Foo.new }
SomeRailsModel = Object.new unless Kernel.const_defined?(:SomeRailsModel)
it 'calls quxo on SomeRailsModel' do
expect(SomeRailsModel).to receive(:quxo)
instance.bar
end
end
This code lets me avoid loading all of Rails and executes very fast. Unfortunately, by default (and I like this) RSpec treats the constant as a partial double and complains that my SomeRailsModel constant doesn't respond to the quxo message. Verifying doubles are nice and I'd like to keep that safety harness. I can individually disable the verification by wrapping it in a special block defined by RSpec.
Finally, the question. What is the recommended way to have fast unit tests on POROs that use Rails models without requiring all of Rails while also keeping verifying doubles functionality enabled? Is there a way to create a "slim" rails_helper that can just load app/models and the minimal subset of ActiveRecord to make the verification work?
After noodling a few ideas with colleagues, here is the concensus solution:
class Foo
def bar
SomeRailsModel.quxo(3)
end
end
require 'spec_helper' # all we need!
RSpec.describe Foo do
let(:instance) { Foo.new }
let(:stubbed_model) do
unless Kernel.const_defined?("::SomeRailsModel")
Class.new { def self.quxo(*); end }
else
SomeRailsModel
end
end
before { stub_const("SomeRailsModel", stubbed_model) }
it 'calls quxo on SomeRailsModel' do
expect(stubbed_model).to receive(:quxo)
instance.bar
end
end
When run locally, we'll check to see if the model class has already been defined. If it has, use it since we've already paid the price to load that file. If it isn't, then create an anonymous class that implements the interface under test. Use stub_const to stub in either the anonymous class or the real deal.
For local tests, this will be very fast. For tests run on a CI server, we'll detect that the model was already loaded and preferentially use it. We get automatic double method verification too in all cases.
If the real Rails model interface changes but the anonymous class falls behind, a CI run will catch it (or an integration test will catch it).
UPDATE:
We will probably DRY this up a bit with a helper method in spec_helper.rb. Such as:
def model_const_stub(name, &blk)
klass = unless Kernel.const_defined?('::' + name.to_s)
Class.new(&blk)
else
Kernel.const_get(name.to_s)
end
stub_const(name.to_s, klass)
klass
end
# DRYer!
let(:model) do
model_const_stub('SomeRailsModel') do
def self.quxo(*); end
end
end
Probably not the final version but this gives a flavor of our direction.
I'm trying to do something fairly simple - add a module with helper methods to a Model test, but I keep getting the following error
uninitialized constant NeighborhoodTest::NeighboorhoodTestHelper
The module is located in test/helpers/neighborhood_test_helper.rb
module NeighborhoodTestHelper
def create_polygon
points = self.geolocate
boundary = Geokit::Polygon.new(points)
end
.
.
end
Per the recommendation in this SO answer, did the following inside test/models/neighborhood_test.rb:
require 'test_helper'
require 'helpers/neighborhood_test_helper'
class NeighborhoodTest < ActiveSupport::TestCase
include NeighboorhoodTestHelper
def setup
#crime = crimes(:arrest)
#neighborhood = neighborhoods(:one)
end
test "neighborhood should contain crime" do
neighborhood_boundary = #neighborhood.create_polygon
crime_location = #crime.geolocate
assert neighborhood_boundary.contains?(crime_location)
end
end
I also tried this SO that didn't work. Anyone know why this approach doesnt work in Models?
tests/some_helper.rb
module SomeHelper
def method1
-----------
-----------
end
def method2
-----------
-----------
end
end
tests/test_helper.rb
require some_helper.rb
You can now access method1 and method2 in any of your test cases. Hope it helps you .
I ran into this today with rspec 3.8, and with other helper tests working just fine, I was very curious to know what made this one spec so special.
In my case, it turned out the spec file name, for whatever reason, was given the same file name as the helper module itself. When trying to load the constant it was looking in the spec file, since it had taken the place of "my_helper" and in turn ignoring the actual module. Adding a _spec at the end of the spec file name allowed this error to go away, and that spec ran as intended after.
I know this is a simple issue, but if you have hundreds upon hundreds of spec files, you may not be constantly looking at the file names.
My class is structured something like this:
class Abc
ONE_CLASS_LEVEL_CONSTANT_BEING_READ_FROM_DB = GloablAttributeValue.read_from_db
def some_method_that_use_above_constant
# this function behaves differently for different values of ONE_CLASS_LEVEL_CONSTANT_BEING_READ_FROM_DB
end
end
Now i want to unit test some_method_that_use_above_constant on the basis of different values ONE_CLASS_LEVEL_CONSTANT_BEING_READ_FROM_DB .
Is this possible to stub out value of ONE_CLASS_LEVEL_CONSTANT_BEING_READ_FROM_DB, so that i can test it for different values in rspec ?
As per this doc, with the version 2.11 of Rspec this should work:
stub_const("Abc::ONE_CLASS_LEVEL_CONSTANT_BEING_READ_FROM_DB", 5)
I have a module saved in /lib as test_functions.rb that looks like this
module TestFunctions
def abc
puts 123
end
end
Going into ruby script/runner, I can see that the module is loading automatically (good ol' convention over configuration and all that...)
>> TestFunctions.instance_methods
=> ["abc"]
so the method is known, let's try calling it
>> TestFunctions.abc
NoMethodError: undefined method `abc' for TestFunctions:Module from (irb):3
Nope. How about this?
>> TestFunctions::abc
NoMethodError: undefined method `abc' for TestFunctions:Module from (irb):4
Test
Nope again.
defined?(TestFunctions::abc) #=> nil, but
TestFunctions.method_defined? :abc #=> true
Like I said at the top, I know I'm being dumb, can anyone de-dumb me?
If you want Module-level functions, define them in any of these ways:
module Foo
def self.method_one
end
def Foo.method_two
end
class << self
def method_three
end
end
end
All of these ways will make the methods available as Foo.method_one or Foo::method_one etc
As other people have mentioned, instance methods in Modules are the methods which are available in places where you've included the Module
I'm going to try to summarise the various answers myself, since each had something valuable to say, but none really got to what I now realise is probably the best response:
I was asking the wrong question because I was doing it wrong.
For reasons I can no longer explain, I wanted a set of completely stand-alone functions in a library, which represented methods I was trying to DRY out of my classes. That can be achieved, using things like
module Foo
def self.method_one
end
def Foo.method_two
end
class << self
def method_three
end
end
def method_four
end
module_function :method_four
end
I could also include my module, either within a class, in which case the methods become part of the class or outside, in which case they are defined on whatever class I'm running inside (Object? Kernel? Irb, if I'm interactive? Probably not a great idea, then)
The thing is, there was no good reason not to have a class in the first place - I'd somehow got on to a train of thought that took me down an seldom-used and frankly slightly weird branch line. Probably a flashback to the days before OO became mainstream (I'm old enough that up to today I've spent a lot more years writing procedural code).
So the functions have moved into a class, where they seem pretty happy, and the class methods thus exposed are being cheerfully used wherever necessary.
You can also use module_function like so:
module TestFunctions
def abc
puts 123
end
module_function :abc
end
TestFunctions.abc # => 123
Now you can include TestFunctions in class and call "abc" from within TestFunctions module.
I messed with this for a while and learned several things. Hopefully this will help someone else out. I am running Rails 3.2.8.
My module (utilities.rb) looks like this and is in the /lib directory of my rails app:
module Utilities
def compute_hello(input_string)
return "Hello #{input_string}"
end
end
My test (my_test.rb) looks like this and is in the /test/unit directory of my rails app:
require "test_helper"
require "utilities"
class MyTest < ActiveSupport::TestCase
include Utilities
def test_compute_hello
x = compute_hello(input_string="Miles")
print x
assert x=="Hello Miles", "Incorrect Response"
end
end
Here are a few things to note: My test extends ActiveSupport::TestCase. This is important because ActiveSupport adds /lib to the $LOAD_PATH. (seehttp://stackoverflow.com/questions/1073076/rails-lib-modules-and)
Secondly, I needed to both "require" my module file, and also "include" the module. Lastly, it is important to note that the stuff that gets included from the module essentially gets placed in the test class. So... be careful that the module that you include doesn't start with "test_". Otherwise, Rails will attempt to run your module method as a test.
You can't call a method in a Module directly. You need to include it in a class. Try this:
>> class MyTest
>> include TestFunctions
>> end
=> MyTest
>> MyTest.new.abc
123
=> nil
You need to include the module
include Testfunctions
Then 'abc' will return something.
You need to prefix your function with the module name because modules are not classes:
Your /lib/test_functions.rb:
module TestFunctions
def TestFunctions.abc
puts 123
end
end
Your code using the module method:
require 'test_functions'
TestFunctions.abc
Today you can do it using module_function notation.
module TestFunctions
def abc
puts 123
end
end
Now TestFunctions.abc prints "123"
A little more about module_function: https://apidock.com/ruby/Module/module_function
Try this code:
service = Class.new { extend TestFunctions }
service.method_four