I'm trying to write an rspec test that would assume a method will return a specific value when it would normally return a random number between 1 and 10.
Here is the code in my lib directory:
def take_off(plane)
fail "Bad weather today. Cannot take off." if stormy_weather? > 8
plane.take_off_plane
planes.delete(plane)
end
def stormy_weather?
rand(10)
end
And here is my test in Rspec:
it 'raises an error when weather is stormy' do
plane = double(:plane)
stormy_weather = 9
allow(plane).to receive(:take_off_plane)
expect{ subject.take_off(plane) }.to raise_error("Bad weather today. Cannot take off.")
end
Thank you in advance to anyone who helps!
You can specify the returned value with and_return:
allow(subject).to receive(:stormy_weather?).and_return(9)
Related
This is my first post here. I'm fairly new to Ruby, especially RSpec and have been running into an issue. I have written a method that uses gets.chomp to receive a player input. However I have this method called in another method
def prompt_move
loop do
#move = gets.chomp.to_i
return move if valid_move?(move)
puts "Invalid input. Enter a column number between 1 and 7"
end
end
def valid_move?(move)
#move.is_a?(Integer) && #move.between?(1, 7)
end
def play_round
print_board
prompt_player
#move = prompt_move
end
Here is the code for my RSpec tests:
describe ConnectFour do
subject(:game) { described_class.new }
let(:player){ double(Player) }
describe '#prompt_move' do
context 'move is a valid input' do
before do
allow(game).to receive(:gets).and_return('3\n')
end
it 'returns move and stops the loop' do
error_message = 'Invalid input. Enter a column number between 1 and 7'
expect(game).to_not receive(:puts).with(error_message)
game.prompt_move
end
end
context 'when given one invalid input, then a valid input' do
before do
letter = 'a'
valid_input = '1'
allow(game).to receive(:gets).and_return(letter, valid_input)
end
it 'completes loop and displays error message once' do
error_message = 'Invalid input. Enter a column number between 1 and 7'
expect(game).to receive(:puts).with(error_message).once
game.prompt_move
end
end
end
If I remove the #prompt_move method from #play_round the tests pass without any issue. However when I try to call it from within #play_round it gives me
NoMethodError:
undefined method `chomp' for nil:NilClass
I have been struggling to figure out what is causing this error so any suggestions would be greatly appreciated!
You're executing code in your class file.
new_game = ConnectFour.new
new_game.play_game
This will run every time you load the file, like when you're testing it. It will prompt for input and run gets. What it's getting is the code of the test file (for some rspec reason). That's invalid, so it keeps running gets until eventually there is no more input and gets returns nil.
Remove that from your class file. Code like that should be in a separate file which requires the class.
I am doing a coding challenge and am trying to make one RSpec test pass, however I am unsure why my code is not passing. The error I am getting after running RSpec is:
1) Plane#land raises an error if already landed
Failure/Error: expect { plane.land }.to raise_error 'Plane can not land as it is already on the ground'
expected Exception with "Plane can not land as it is already on the ground" but nothing was raised
# ./spec/plane_spec.rb:22:in `block (3 levels) in '
the RSpec test code is:
describe Plane do
let(:plane) { Plane.new }
describe '#land' do
it 'raises an error if already landed' do
plane.land
expect { plane.land }.to raise_error 'Plane can not land as it is already on the ground'
end
end
end
And my main code is:
class Plane
def initialize
#in_air = true
end
def land
fail "Plane can not land as it is already on the ground" if already_landed?
#in_air = false
end
end
I have tried substituting back plane for Plane.new and tried using raise instead of fail and I have double checked, but I can not see why it is not working.
Many thanks
You haven't defined a already_landed? method. That means calling already_landed? would always raise a NoMethodError: undefined method 'already_landed?' exception, but never the expected Plane can not land... exception. And therefore your expectation does not pass.
Just add the already_landed? method to your model:
class Plane
def initialize
#in_air = true
end
def land
fail "Plane can not land as it is already on the ground" if already_landed?
#in_air = false
end
def already_landed?
!#in_air
end
end
Btw: Does it makes sense that a newly created plane will already be in_air? I would expect in_air to be false on initialization and that you need to start first. I would change that behavior:
class Plane
attr_accessor :flying
def fly
# no exception here, I assume it is save to continue flying, when already in air
self.flying = true
end
def land
fail 'Plane can not land as it is already on the ground' if landed
self.flying = false
end
def landed
!flying
end
end
plane = Plane.new
plane.land
#=> RuntimeError: Plane can not land as it is already on the ground
I am writing a small program for a train system.
I have a passenger, coach, train and station class (and thus, a spec test for each).
My test for my passenger class is as such:
let (:passenger) {Passenger.new}
it "should not be touched in to a station when initialized" do
expect(passenger.touchedin?).to be false
end
it "should be able to enter coach" do
coach = Coach.new
passenger.enter(coach)
expect{coach.to receive(:enter)}
end
it "should be able to alight coach" do
coach = Coach.new
passenger.alight(coach)
expect{coach.to receive(:alight)}
end
it "should be able to touch into station" do
station = Station.new
passenger.touchin(station)
expect{station.to receive(:touchin)}
end
it "should be able to touch out of station" do
station = Station.new
passenger.touchout(station)
expect{station.to receive(:touchout)}
end
end
And my passenger class is like this (at the moment :p):
class Passenger
def initialize
#touchedin = false
end
def enter(coach)
end
def touchedin?
#touchedin
end
def alight(coach)
end
def touchin(station)
end
def touchout(station)
end
end
I am unsure how to satisfy my tests, if my tests are even correct in the first place.
Any help is really appreciated!
You've not really said how you're modeling the relationship between coaches and passengers, but one way I could think of could be as follows. I'm just putting enough for the coach/passenger relationship (so nothing about touching in as this involves the station) - and I'm using minitest syntax, but I think you can get the idea of what's happening.
class Coach
def initialize
#passengers = []
end
...
end
class Passenger
def initialize
#touched_in = false
end
def alight(coach)
coach.passengers << self.uid # or self, if you want the whole passenger object available
end
...
end
coach = Coach.new
assert_empty coach.passengers
joe = Passenger.new
refute_includes coach.passengers, joe.uid # or joe
joe.alight(coach)
assert_includes coach.passengers, joe.uid # or joe
I am describing class on RSpec
class Pupil
def initialize(name, dateOfBirth)
#name = name
#dateOfBirth = dateOfBirth
end
def name
#name
end
def ages
#should calculate ages
end
end
describe Pupil do
context do
pupil = Pupil.new("Stanislav Majewski", "1 april 1999")
it "should returns name" do
pupil.name.should eq("Stanislav Majewski")
end
it "should calculates ages" do
#not described
end
end
end
RSpec returns:
..
Finished in 0.00203 seconds
2 examples, 0 failures
Is there an elegant way to display a failure message that the method is not described?
If you're concerned that you'll create a test and forget to put anything it in (sometimes I'll create three tests I know I'll need, and work on each of them in turn) then you can do the following:
it "should calculates ages" do
fail
end
OR
it "should calculates ages"
...and that's all (no block) will mark the test as pending automatically. In other words, don't fill out your tests until they have actual test code in them.
Also, if you don't test any assertions (i.e. if your spec doesn't contain any lines that have a call to should in them), your spec will appear to pass. This has happened to me a few times, where I write a new test, expecting it to fail, and it doesn't because I forgot to include the call to should which is what actually tests the assertion.
I'm trying to make this test fail :)
it "should display the question" do
#ui.should_receive(:puts).with("What's your name?").once
#ui.ask_question("What's your name?")
end
At the moment it passes even if I don't call puts in my function.
Basically, #ui should call .puts on an object that probably defaults to $stdout. Then in your tests, you can replace $stdout with a StringIO object that you can set expectations on. This has the added benefit of making your #ui object more flexible.
Given the code:
require 'rubygems'
require 'spec'
class UI
def ask_question(q)
end
end
describe UI do
before do
#ui = UI.new
end
it "should display the question" do
#ui.should_receive(:puts).with("Whats your name?").once
#ui.ask_question("Whats your name?")
end
end
I get the failure:
F
1) Spec::Mocks::MockExpectationError in 'UI should display the question'
#<UI:0xb738effc> expected :puts with ("Whats your name?") once, but received it 0 times /home/avdi/tmp/puts_spec.rb:15:
Finished in 0.002575 seconds
1 example, 1 failure
What version of RSpec are you using?
You can try stringio or ZenTest, the following ruby-talk thread has more info.