Question

我遇到的问题是，当随机数低于20时，这些测试才会通过，我如何在测试中考虑到这一点？

我的测试：

it 'a plane cannot take off when there is a storm brewing' do
    airport = Airport.new [plane]
    expect(lambda { airport.plane_take_off(plane) }).to raise_error(RuntimeError) 
end

it 'a plane cannot land in the middle of a storm' do
    airport = Airport.new []
    expect(lambda { airport.plane_land(plane) }).to raise_error(RuntimeError) 
end

我的代码摘录：

def weather_rand
  rand(100)
end

def plane_land plane
  raise "Too Stormy!" if weather_ran <= 20
  permission_to_land plane
end

def permission_to_land plane
  raise "Airport is full" if full?
  @planes << plane
  plane.land!
end

def plane_take_off plane
  raise "Too Stormy!" if weather_ran <= 20
  permission_to_take_off plane
end

def permission_to_take_off plane
  plane_taking_off = @planes.delete_if {|taking_off| taking_off == plane }
  plane.take_off!
end

Answer 1

您需要存根weather_rand方法以返回已知值以匹配您要测试的内容。

https://www.relishapp.com/rspec/rspec-mocks/v/2-14/docs/method-stubs

例如：

it 'a plane cannot take off when there is a storm brewing' do
    airport = Airport.new [plane]
    airport.stub(:weather_rand).and_return(5)
    expect(lambda { airport.plane_take_off(plane) }).to raise_error(RuntimeError) 
end

Answer 2

使用rand生成一系列数字，以涵盖特定情况，以便覆盖角落案例。我会使用let来做这样的天气范围的懒惰实例化：

let(:weather_above_20) { rand(20..100) }
let(:weather_below_20) { rand(0..20) }

然后我会在我的测试中使用weather_above_20和weather_below_20变量。最好隔离测试条件。

关于懒惰实例化的更多信息： https://www.relishapp.com/rspec/rspec-core/docs/helper-methods/let-and-let

Answer 3

allow_any_instance_of(Object).to receive(:rand).and_return(5)

如何在我的rspec测试中考虑随机数？

3 个答案: