Here is the code for my specs and class:
describe Game do
before(:each) do
#game = Factory.build(:game)
end
describe '#no_books?' do
it 'should return true if books attribute is empty' do
#game.stub(:books).and_return([])
#game.no_books?.should be_true
end
it 'should return false if books attribute is present' do
#game.no_books?.should be_false
end
end
end
class Game
attr_reader :books
def initialize
#books = parse_books
end
def no_books?
#books.empty?
end
protected
def parse_books
# return books
end
end
I then get a friendly spec failure message:
Game#no_books? should return true if books attribute is empty
Failure/Error: #game.no_books?.should be_true
expected false to be true
It's as if that method is getting called before the attribute books get initialized with a value. Can someone explain to me what's going here?
Your no_books? implementation is using the instance variable directly in its check, bypassing your stub. If you change no_books? to return books.empty?, it will call the stub instead.
If you really, really want to keep using the instance variable, you can set it in #game via instance_variable_set like this:
#game.instance_variable_set("#books", [])
Related
I am building a DSL and have this module
module EDAApiBuilder
module Client
attr_accessor :api_client, :endpoint, :url
def api_client(api_name)
#apis ||= {}
raise ArgumentError.new('API name already exists.') if #apis.has_key?(api_name)
#api_client = api_name
#apis[#api_client] = {}
yield(self) if block_given?
end
def fetch_client(api_name)
#apis[api_name]
end
def endpoint(endpoint_name)
raise ArgumentError.new("Endpoint #{endpoint_name} already exists for #{#api_client} API client.") if fetch_client(#api_client).has_key?(endpoint_name)
#endpoint = endpoint_name
#apis[#api_client][#endpoint] = {}
yield(self) if block_given?
end
def url=(endpoint_url)
fetch_client(#api_client)[#endpoint]['url'] = endpoint_url
end
end
end
so that I have tests like
context 'errors' do
it 'raises an ArgumentError when trying to create an already existent API client' do
expect {
obj = MixinTester.new
obj.api_client('google')
obj.api_client('google')
}.to raise_error(ArgumentError,'API name already exists.')
end
it 'raises an ArgumentError when trying to create a repeated endpoint for the same API client' do
expect {
obj = MixinTester.new
obj.api_client('google') do |apic|
apic.endpoint('test1')
apic.endpoint('test1')
end
}.to raise_error(ArgumentError,"Endpoint test1 already exists for google API client.")
end
end
I would rather have #api_clientwritten as an assignment block
def api_client=(api_name)
so that I could write
obj = MixinTester.new
obj.api_client = 'google' do |apic| # <=== Notice the difference here
apic.endpoint('test1')
apic.endpoint('test1')
end
because I think this notation (with assignment) is more meaningful. But then, when I run my tests this way I just get an error saying that the keyworkd_do is unexpected in this case.
It seems to me that the definition of an assignment block is syntactic sugar which won't contemplate blocks.
Is this correct? Does anyone have some information about this?
By the way: MixinTester is just a class for testing, defined in my spec/spec_helper.rb as
class MixinTester
include EDAApiBuilder::Client
end
SyntaxError
It seems to me that the definition of an assignment [method] is syntactic
sugar which won't contemplate blocks.
It seems you're right. It looks like no method with = can accept a block, even with the normal method call and no syntactic sugar :
class MixinTester
def name=(name,&block)
end
def set_name(name, &block)
end
end
obj = MixinTester.new
obj.set_name('test') do |x|
puts x
end
obj.name=('test') do |x| # <- syntax error, unexpected keyword_do, expecting end-of-input
puts x
end
Alternative
Hash parameter
An alternative could be written with a Hash :
class MixinTester
def api(params, &block)
block.call(params)
end
end
obj = MixinTester.new
obj.api client: 'google' do |apic|
puts apic
end
#=> {:client=>"google"}
You could adjust the method name and hash parameters to taste.
Parameter with block
If the block belongs to the method parameter, and not the setter method, the syntax is accepted :
def google(&block)
puts "Instantiate Google API"
block.call("custom apic object")
end
class MixinTester
attr_writer :api_client
end
obj = MixinTester.new
obj.api_client = google do |apic|
puts apic
end
# =>
# Instantiate Google API
# custom apic object
It looks weird, but it's pretty close to what you wanted to achieve.
I'm writing RSpec unit tests for a CommandLineInterface class that I've created for my Directory object. The CommandLineInterface class uses this Directory object to print out a list of people in my Directory. Directory has a #sort_by(param) method that returns an array of strings. The order of the strings depends on the param passed to the #sort_by method (e.g., sort_by("gender"). What would be the correct way to mock out this Directory behavior in my CLI specs? Would I use an instance_double? I am not sure how to do this for a method that takes parameters, like sorting by gender.
I'm only using Ruby and RSpec. No Rails, ActiveRecord, etc. being used here.
Snippets from the class and method I want to mock out:
class Directory
def initialize(params)
#
end
def sort_by(param)
case param
when "gender" then #people.sort_by(&:gender)
when "name" then #people.sort_by(&:name)
else raise ArgumentError
end
end
end
It all depends on how your objects are collaborating.
Some information is lacking in your question:
How does CommandLineInterface use Directory? Does it create an instance by itself or does it receive one as an argument?
Are you testing class methods or instance methods? (Prefer instance methods)
Here's how you could do it if you pass in the dependent object:
require 'rspec/autorun'
class A
def initialize(b)
#b = b
end
def foo(thing)
#b.bar(thing)
end
end
RSpec.describe A do
describe '#foo' do
context 'when given qux' do
let(:b) { double('an instance of B') }
let(:a) { A.new(b) }
it 'calls b.bar with qux' do
expect(b).to receive(:bar).with('qux')
a.foo('qux')
end
end
end
end
If the class initializes the dependant object and it isn't important to know which instance got the message you can do this:
require 'rspec/autorun'
B = Class.new
class A
def initialize
#b = B.new
end
def foo(thing)
#b.bar(thing)
end
end
RSpec.describe A do
describe '#foo' do
context 'when given qux' do
let(:a) { A.new }
it 'calls b.bar with qux' do
expect_any_instance_of(B).to receive(:bar).with('qux')
a.foo('qux')
end
end
end
end
If you just want to stub out the return value and not test whether the exact message was received, you can use allow:
require 'rspec/autorun'
B = Class.new
class A
def initialize
#b = B.new
end
def foo(thing)
thing + #b.bar(thing)
end
end
RSpec.describe A do
describe '#foo' do
context 'when given qux' do
let(:a) { A.new }
it 'returns qux and b.bar' do
allow_any_instance_of(B).to receive(:bar).with('qux') { 'jabber' }
expect(a.foo('qux')).to eq('quxjabber')
end
end
end
end
How can I create a dynamic property in ruby? This functionality exists in python.
class Example(object):
value = "This is property!"
class Test(object):
#property
def check(self):
return Example
test = Test()
print(test.check.value) # This is property!
How can I do the same in ruby?
class Example
def value
"This is property!"
end
end
class Test
def check
Example.new
end
end
test = Test.new
puts test.check.value # This is property!
class Test
def check
"This is property!"
end
end
test = Test.new
puts(test.check) # This is property!
Not sure what you want from your example. Properties (from what I've seen) are usually used to create setters and getters. You can have that in Ruby with attr_accessor:
class Test
attr_accessor :check
end
You can call attr_accessor anytime you want an attribute:
class Test
%w{this are possible attribute names}.each do |att|
attr_accessor att
end
end
Or
Class Test
end
test = Test.new
Test.send(:attr_accessor, :whatever)
test.whatever = "something"
test.whatever # => "something"
If you only want a getter you have attr_reader, and there's attr_writer for a writer. They all, for an attribute called attribute_name, use an instance variable called #attribute_name. They all may be built with instance_variable_set and instance_variable_get, which allow dynamically setting and getting instance variables.
You can use ruby's method_missing to achieve something similar:
class TestCheck
def method_missing(methodId)
if(methodId.id2name == "check")
puts "check called"
else
puts "method not found"
end
end
end
t = TestCheck.new
t.check #=> "check called"
t.something_else #=> "method not found"
Reference: Ruby docs
When testing class methods, I don't need an instance to be created automatically. Is an implicit subject created automatically, or only when referenced?
describe MyClass do
it 'uses implicit subject' do
subject.my_method.should be_true
end
it 'does not create a subject' do
MyClass.works?.should be_true
# subject should not have been created
end
end
subject appears to be a method which creates the object necessary and returns it. So it would only create a subject object when called.
It's easy enough to test yourself though...
class MyClass
cattr_accessor :initialized
def initialize
MyClass.initialized = true
end
def my_method
true
end
def self.works?
true
end
end
describe MyClass do
it 'uses implicit subject' do
MyClass.initialized = false
subject.my_method.should be_true
MyClass.initialized.should == true
end
it 'does not create a subject' do
MyClass.initialized = false
MyClass.works?.should be_true
MyClass.initialized.should == false
end
end
Those specs pass, proving that it's lazy.
I can take a block of code, instance_exec it, and get the proper result. I would like to take a method off a different object and call one of it's methods in my scope. When I take a method from a different object, turn it into a proc, and then instance_exec it, I don't get the expected result. Code follows.
class Test1
def ohai(arg)
"magic is #{#magic} and arg is #{arg}"
end
end
class Test2
def initialize
#magic = "MAGICAL!"
end
def scope_checking
#magic
end
def do_it
ohai = Test1.new.method(:ohai)
self.instance_exec("foobar", &ohai)
end
end
describe "Test2 and scopes" do
before do
#t2 = Test2.new
end
it "has MAGICAL! in #magic" do
#t2.scope_checking.should == "MAGICAL!"
end
# This one fails :(
it "works like I expect converting a method to a proc" do
val = #t2.do_it
val.should == "magic is MAGICAL! and arg is foobar"
end
it "should work like I expect" do
val = #t2.instance_exec do
"#{#magic}"
end
val.should == "MAGICAL!"
end
end
It seems that, in Ruby, methods defined using def some_method are bound permanently to the class they're defined in.
So, when you call .to_proc on them they keep the binding of their original implementation, and you cannot rebind them. Well, you can, but only to an object of the same type as the first one. It's possible I could do some fancyness with inheritance, but I don't think so.
The solution becomes instead of using methods, I just put actual Procs into variables and use them then, as they're not bound until execution time.
not sure how good of an idea this is, but this passes your tests:
class Test1
def ohai(arg, binding)
eval('"magic is #{#magic} "', binding).to_s + "and arg is #{arg}"
end
end
class Test2
def initialize
#magic = "MAGICAL!"
end
def scope_checking
#magic
end
def get_binding
return binding()
end
def do_it
self.instance_exec(get_binding) {|binding| Test1.new.ohai("foobar", binding) }
end
end