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Feature: Xor
Takes a variable number of contracts. The contract passes if one and only one
of the contracts pass.
```ruby
Contract C::Xor[Float, C::Neg] => String
```
This example will validate first argument of a method and accept either
`Float` or natural integer, but not both.
Background:
Given a file named "xor_usage.rb" with:
"""ruby
require "contracts"
C = Contracts
class Example
include Contracts::Core
Contract C::Xor[Float, C::Neg] => String
def strange_number(number)
number.to_i.to_s
end
end
"""
Scenario: Accepts float
Given a file named "accepts_float.rb" with:
"""ruby
require "./xor_usage"
puts Example.new.strange_number(3.7)
"""
When I run `ruby accepts_float.rb`
Then output should contain:
"""
3
"""
Scenario: Accepts negative integer
Given a file named "accepts_negative_integer.rb" with:
"""ruby
require "./xor_usage"
puts Example.new.strange_number(-7)
"""
When I run `ruby accepts_negative_integer.rb`
Then output should contain:
"""
-7
"""
Scenario: Rejects negative float
Given a file named "rejects_negative_float.rb" with:
"""ruby
require "./xor_usage"
puts Example.new.strange_number(-3.5)
"""
When I run `ruby rejects_negative_float.rb`
Then output should contain:
"""
: Contract violation for argument 1 of 1: (ParamContractError)
Expected: (Float xor Neg),
Actual: -3.5
Value guarded in: Example::strange_number
With Contract: Xor => String
"""
Scenario: Rejects positive integer
Given a file named "rejects_positive_integer.rb" with:
"""ruby
require "./xor_usage"
puts Example.new.strange_number(9)
"""
When I run `ruby rejects_positive_integer.rb`
Then output should contain:
"""
: Contract violation for argument 1 of 1: (ParamContractError)
Expected: (Float xor Neg),
Actual: 9
Value guarded in: Example::strange_number
With Contract: Xor => String
"""
Scenario: Rejects other values
Given a file named "rejects_other.rb" with:
"""ruby
require "./xor_usage"
puts Example.new.strange_number(:foo)
"""
When I run `ruby rejects_other.rb`
Then output should contain:
"""
: Contract violation for argument 1 of 1: (ParamContractError)
Expected: (Float xor Neg),
Actual: :foo
Value guarded in: Example::strange_number
With Contract: Xor => String
"""
|
