emplyee pay per month

employee_spec.rb

#encoding: utf-8
class Employee
	WORK_DAY_OF_MONTH = 20
	DOUBLE = 2
	attr_reader :name, :pay_per_day
	def initialize name, pay_per_day
		@name = name
		@pay_per_day = pay_per_day
		@pay_off = @over_time = 0
	end

	def pay_per_month
		@pay_per_day * (WORK_DAY_OF_MONTH - @pay_off + @over_time)
	end

	def payoff=(day)
		@pay_off = (day >= WORK_DAY_OF_MONTH)? WORK_DAY_OF_MONTH : day
	end

	def overtime=(day)
		# 加班的话工资double
		@over_time = day * DOUBLE
	end

end

describe Employee do
	it 'should initialize Employee with name fred' do
		e = Employee.new 'fred', 1
		e.name.should eql('fred')
	end

	it 'should initialize Employee with name tom' do
		e = Employee.new 'tom', 2
		e.name.should eql('tom')
	end

	it 'should initialize Employee with pay per day' do
		e = Employee.new 'tom', 100
		e.name.should eql('tom')
		e.pay_per_day.should eql(100)

		e = Employee.new 'fred', 200
		e.pay_per_day.should eql(200)
	end

	it 'should calculate pay per month successfuly' do
		e = Employee.new 'fred', 200
		e.pay_per_month.should eql(4000)

		e = Employee.new 'tom', 100
		e.pay_per_month.should eql(2000)
	end

	it 'should calculate pay per month when payoff' do
		e = Employee.new 'fred', 200
		e.payoff = 1
		e.pay_per_month.should == 3800

		e = Employee.new 'tom', 100
		e.payoff = 0
		e.pay_per_month.should == 2000
	end

	it 'at most 20 days pay off a month' do
		e = Employee.new 'fred', 200
		e.payoff = 100
		e.pay_per_month.should == 0

		e = Employee.new 'tom', 100
		e.payoff = 20
		e.pay_per_month.should == 0
	end

	it 'should be double when ot' do
		e = Employee.new 'fred', 200
		e.overtime = 1
		e.pay_per_month.should == 4400

		e = Employee.new 'tom', 100
		e.overtime = 1
		e.payoff = 1
		e.pay_per_month.should == 2100
	end

end