Set a default message for a custom error class - ruby

Question

I have created a custom error class called MyError and a separate class called MyClass that raises this error in its class method self.raiser. I have also created to rspec expectations to test that MyError is raised and that MyError prints the message my error:
class MyError < StandardError
def self.message
'my error'
end
end
class MyClass
def self.raiser
raise MyError
end
end
describe MyClass do
specify{ expect{ MyClass.raiser }.to raise_exception 'my error' }
specify{ expect{ MyClass.raiser }.to raise_exception MyError }
end
Here's what happens when I run rspec:
$ rspec spec/raise_error.rb --format documentation
MyClass
should raise Exception with "my error" (FAILED - 1)
should raise MyError
Failures:
1) MyClass should raise Exception with "my error"
Failure/Error: specify{ expect{ MyClass.raiser }.to raise_exception 'my error' }
expected Exception with "my error", got #<MyError: MyError> with backtrace:
# ./spec/raise_error.rb:9:in `raiser'
# ./spec/raise_error.rb:14:in `block (3 levels) in <top (required)>'
# ./spec/raise_error.rb:14:in `block (2 levels) in <top (required)>'
# ./spec/raise_error.rb:14:in `block (2 levels) in <top (required)>'
Finished in 0.01662 seconds (files took 0.08321 seconds to load)
2 examples, 1 failure
Failed examples:
rspec ./spec/raise_error.rb:14 # MyClass should raise Exception with "my error"
Both of these expectations should pass. got #<MyError: MyError> is bizarre and makes no sense at all. It should be got #<MyError: "my error">
Also, I do not think this is an rspec error:
2.2.1 :007 > require 'rspec'
=> true
2.2.1 :008 > require_relative 'spec/raise_error.rb'
=> true
2.2.1 :009 > MyClass.raiser
MyError: MyError

Answer 1

You have to defined the method message as an instance method, not the class method as you tried.
I rewrote the custom error class :
class MyError < StandardError
def message
'my error'
end
end
class MyClass
def self.raiser
raise MyError
end
end
Here is my spec file :
require_relative "../a.rb"
describe MyClass do
it 'expects the Error class message' do
expect { MyClass.raiser }.to raise_exception 'my error'
end
it 'expects the Error class name' do
expect { MyClass.raiser }.to raise_exception MyError
end
end
Lets run the spec:
[arup#Ruby]$ rspec -fd spec/a_spec.rb
MyClass
expects the Error class message
expects the Error class name
Finished in 0.00232 seconds (files took 0.16898 seconds to load)
2 examples, 0 failures