[英]How do I take into account the random number in my rspec tests?
I am having a problem that these tests only pass when the random number is below 20, how do I account for this in my tests? 我有一个问题,这些测试仅在随机数小于20时通过,我如何在测试中说明这一点?
My tests: 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
My code excerpt: 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
You would need to stub the weather_rand
method to return a known value to match what you are trying to test. 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 https://www.relishapp.com/rspec/rspec-mocks/v/2-14/docs/method-stubs
For example: 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
Use rand
to generate a range of numbers that will cover a specific case so you cover the corner cases. 使用
rand
生成一系列覆盖特定情况的数字,以便覆盖角落情况。 I would use let
to do the lazy instantiation of the weather ranges like this: 我会用
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) }
Then I would use the weather_above_20
and weather_below_20
variables in my tests. 然后我会在我的测试中使用
weather_above_20
和weather_below_20
变量。 It is always best to isolate test conditions. 最好隔离测试条件。
Little more about the lazy instantiation: https://www.relishapp.com/rspec/rspec-core/docs/helper-methods/let-and-let 关于延迟实例的更多信息: https : //www.relishapp.com/rspec/rspec-core/docs/helper-methods/let-and-let
allow_any_instance_of(Object).to receive(:rand).and_return(5)
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