class Sham

@@shams = {}

# Over-ride module's built-in name method, so we can re-use it for

# generating names. This is a bit of a no-no, but we get away with

# it in this context.

def self.name(*args, &block)

method_missing(:name, *args, &block)

end

def self.method_missing(symbol, *args, &block)

if block_given?

@@shams[symbol] = Sham.new(symbol, args.pop || {}, &block)

else

sham = @@shams[symbol]

raise "No sham defined for #{symbol}" if sham.nil?

sham.fetch_value

end

end

def self.clear

@@shams = {}

end

def self.reset(scope = :before_all)

@@shams.values.each { |sham| sham.reset(scope) }

end

def self.define(&block)

Sham.instance_eval(&block)

end

def initialize(name, options = {}, &block)

@name = name

@generator = block

@offset = 0

@unique = options.has_key?(:unique) ? options[:unique] : true

generate_values(12)

end

def reset(scope)

if scope == :before_all

@offset, @before_offset = 0, nil

elsif @before_offset

@offset = @before_offset

else

@before_offset = @offset

end

end

def fetch_value

# Generate more values if we need them.

if @offset >= @values.length

generate_values(2 * @values.length)

raise "Can't generate more unique values for Sham.#{@name}" if @offset >= @values.length

end

result = @values[@offset]

@offset += 1

result

end

private

def generate_values(count)

@values = seeded { (1..count).map(&@generator) }

@values.uniq! if @unique

end

def seeded

begin

srand(1)

yield

ensure

srand

end

end

end