expect_any_instance_of with an object argument - ruby

Question

I am testing a class's initialization block as below
class A
attr_accessor :client
def initialize(options, configuration)
self.client = B.new(options)
config = C.new(
url: configuration[:url],
headers: configuration[:headers],
username: configuration[:username],
password: configuration[:password]
)
client.configure(config)
end
end
class C
def initialize(options)
# does something with options hash
end
end
class B
def initialize(options)
# does something with options hash
end
def configure(config)
# some configuration with config object
end
end
My test case is as follows:
let(:options) {
{
force_basic_auth: true
}
}
let(:configuration) {
{
url: 'https://localhost:3000',
headers: { awesome: true },
username: 'test',
password: 'pass'
}
}
let(:api_config) {
C.new(configuration)
}
it 'configures object with passed params' do
expect_any_instance_of(B).to receive(:configure)
.with(api_config)
A.new(
options,
configuration
)
end
This fails my test case because the object that is created in the initialization block has a different object_id than the object_id of api_config which I am using in the expectations.
-[#<C:0x00000002b51128 #url="https://localhost:3000", #headers={:awesome=>true}, #username="test", #password="pass">]
+[#<C:0x00000002a1b628 #url="https://localhost:3000", #headers={:awesome=>true}, #username="test", #password="pass">]
Seeing that failure I was thinking whether it's a best practice to pass such objects directly in the initialization block. I mean I can fix it by directly passing the object in the initialization block.
There are many functions which are initializing the A class with a hash option being passed because of which I am doing it in the current way.
Is there a way to expect the contents of the object passed in rspec instead of verifying the objects are same ? Is passing the object directly in the initialization a more better approach ?

Answer 1

You can define arbitrary expectation handling to check the value of the parameter checked (see here):
it 'configures object with passed params' do
expect_any_instance_of(B).to receive(:configure) do |config|
expect(config).to be_a(C)
expect(config.url).to eq(configuration[:url])
expect(config.headers).to eq(configuration[:headers])
# ...
end
A.new(
options,
configuration
)
end

Answer 2

You want the configuration hash (rather than the object) under B.configure(config), so your class has to change slightly to accommodate.
Class file
class A
attr_accessor :client
def initialize(options, configuration)
self.client = B.new(options)
config = C.new(
url: configuration[:url],
headers: configuration[:headers],
username: configuration[:username],
password: configuration[:password]
)
client.configure(config.options)
end
end
class C
attr_reader :options
def initialize(options)
#options = options
end
end
class B
def initialize(options)
# does something with options hash
end
def configure(config)
# some configuration with config object
end
end
Here's what your RSpec code would look like.
describe do
let(:options) do
{
force_basic_auth: true
}
end
let(:configuration) do
{
url: 'https://localhost:3000',
headers: { awesome: true },
username: 'test',
password: 'pass'
}
end
let(:my_a_object) { A.new(options, configuration) }
let(:my_b_object) { B.new(options) }
it 'configures object with passed params' do
allow(B).to receive(:new).with(options).and_return(my_b_object)
expect(my_b_object).to receive(:configure).with(configuration)
my_a_object
end
end