Module: Whitestone::Assertion::Guards

Extended by:
Guards
Included in:
Base, Guards
Defined in:
lib/whitestone/assertion_classes.rb

Overview

Various methods to guard against invalid assertions. All of these raise AssertionSpecificationError if there is a problem.

Instance Method Summary collapse

Instance Method Details

#args_or_block_one_only(args, block) ⇒ Object

Return a lambda that can be run. If the user specified a block, it’s that. If not, it’s the first argument. If both or neither, it’s an error. If there’s more arguments than necessary, it’s an error.



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# File 'lib/whitestone/assertion_classes.rb', line 37

def args_or_block_one_only(args, block)
  if block and args.empty?
    block
  elsif !block and args.size == 1
    lambda { args.first }
  else
    raise AssertionSpecificationError, "Improper arguments to T"
  end
end

#block_required(block) ⇒ Object 



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# File 'lib/whitestone/assertion_classes.rb', line 74

def block_required(block)
  unless block
    raise AssertionSpecificationError, "The method requires a block"
  end
  block
end

#no_block_allowed ⇒ Object 



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# File 'lib/whitestone/assertion_classes.rb', line 68

def no_block_allowed
  if @block
    raise AssertionSpecificationError, "This method doesn't take a block"
  end
end

#one_argument(array) ⇒ Object 



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# File 'lib/whitestone/assertion_classes.rb', line 47

def one_argument(array)
  unless array.size == 1
    raise AssertionSpecificationError, "Exactly one argument required"
  end
  array.first
end

#two_arguments(array) ⇒ Object 



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# File 'lib/whitestone/assertion_classes.rb', line 54

def two_arguments(array)
  unless array.size == 2
    raise AssertionSpecificationError, "Exactly two arguments required"
  end
  array
end

#two_or_three_arguments(array) ⇒ Object 



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# File 'lib/whitestone/assertion_classes.rb', line 61

def two_or_three_arguments(array)
  unless array.size == 2 or array.size == 3
    raise AssertionSpecificationError, "Exactly two or three arguments required"
  end
  array
end

#type_check(args, types) ⇒ Object 



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# File 'lib/whitestone/assertion_classes.rb', line 81

def type_check(args, types)
  if Class === types
    types = args.map { types }
  end
  if types.size != args.size
    raise AssertionSpecificationError, "Incorrect number of types provided"
  end
  args.zip(types).each do |arg, type|
    unless arg.is_a? type
      msg = "Argument error: expected #{type}; "\
            "got #{arg.inspect} (#{arg.class})"
      raise AssertionSpecificationError, msg
    end
  end
end