Class: Contracts::Invariants::Invariant

Inherits:
Object
  • Object
show all
Defined in:
lib/contracts/invariants.rb

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(klass, name, &condition) ⇒ Invariant

Returns a new instance of Invariant.



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# File 'lib/contracts/invariants.rb', line 38

def initialize(klass, name, &condition)
  @klass     = klass
  @name      = name
  @condition = condition
end

Class Method Details

.failure_callback(data) ⇒ Object

Raises:



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# File 'lib/contracts/invariants.rb', line 59

def self.failure_callback(data)
  raise InvariantError, failure_msg(data)
end

.failure_msg(data) ⇒ Object 



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# File 'lib/contracts/invariants.rb', line 63

def self.failure_msg(data)
  %{Invariant violation:
      Expected: #{data[:expected]}
      Actual: #{data[:actual]}
      Value guarded in: #{data[:target].class}::#{Support.method_name(data[:method])}
      At: #{Support.method_position(data[:method])}}
end

Instance Method Details

#check_on(target, method) ⇒ Object 



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# File 'lib/contracts/invariants.rb', line 48

def check_on(target, method)
  return if target.instance_eval(&@condition)

  self.class.failure_callback(
    :expected => expected,
    :actual   => false,
    :target   => target,
    :method   => method
  )
end

#expected ⇒ Object 



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# File 'lib/contracts/invariants.rb', line 44

def expected
  "#{@name} condition to be true"
end