For 2023 (and 2024 ...) - we are now fully retired from IT training. We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.
Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!
I am also active in many other area and still look after a lot of web sites - you can find an index ((here)) |
Second step Cucumber and Gherkin - beyond Hello World
Articles in this "Introduction to Cucumber" series:
[link] - Installing Cucumber for Ruby
[link] - Hello Test Cucumber World
[link] - First real tests / second example
[link] - Improved tests with RSpec
Let's look at an example where I calculate a train's capacity in a class, based on the number of seats and the Department for Transport's specification of 40% overloading for local trains which stop at least every half hour.
I'll define my feature - second/capacity.feature:
Feature: Check that a train's capacity is 1.4 x number of seats
Scenario: Calculating people that can be carried
Given I have a 3 coach train with 75 seats per carriage
When I ask what the capacity is
Then I should be told it is 315
When I run that, Gherkin / Cucumber gives me a template for the test code:
which I can paste directly into a ruby steps file:
WomanWithCat:cuc grahamellis$ mkdir second/step_definitions
WomanWithCat:cuc grahamellis$ cat > second/step_definitions/second_steps.rb
Given(/^I have a (\d+) coach train with (\d+) seats per carriage$/) do |arg1, arg2|
pending # express the regexp above with the code you wish you had
end
When(/^I ask what the capacity is$/) do
pending # express the regexp above with the code you wish you had
end
Then(/^I should be told it is (\d+)$/) do |arg1|
pending # express the regexp above with the code you wish you had
end
WomanWithCat:cuc grahamellis$
Running that, I'm told that the given clause is pending and (as a result of it being incomplete) the when and then clauses are skipped.
You'll note keywords Given, When, Then, And and But ... and it turns out they're all 'linking words' which you can replace with "* bullets if you prefer.
Note also that each scenario (if you have multiple scenarios) is going to be independent of the other scenarios - each must be built from scratch as you won't have data transferred across. Keeping the scenarios independent in this way is a big help later on - you may feel it's a bit much to setup every time (but there are ways of sharing code).
I can now implement my tests (replacing pending with what the code should be to run the tests, and then implement my class, and the result is my final scenario (in Gherkin) with the test patterns it's helped me generate and the class code that's been used to satisfy those test patterns:
The steps file has become:
Given(/^I have a (\d+) coach train with (\d+) seats per carriage$/) do |arg1, arg2|
@mytrain = Train.new(arg1.to_i,arg2.to_i)
end
When(/^I ask what the capacity is$/) do
@capacity = @mytrain.getcapacity
end
Then(/^I should be told it is (\d+)$/) do |arg1|
if @capacity == arg1.to_i
pass
else
fail
end
end
Note that the incoming variables from the regular expression match are all strings, and need to be converted to integers or floats as the case my be before they're passed into the methods / class we're testing.
And the class that we're testing:
class Train
def initialize (coaches,seats)
@coaches = coaches
@seats = seats
end
def getcapacity
return (@coaches * @seats * 1.4).to_i
end
end
For this example ... our code
1. Feature file [here]
2. Step implementation [here]
3. Code to implement the behaviour [here] (written 2015-01-03)
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles R221 - Ruby - Introduction to Cucumber [4380] Behaviour Driven Development / Ruby and Cucumber - (2015-01-02) [4381] Installing Cucumber (Ruby) - (2015-01-03) [4383] Improved test in Cucumber with RSpec - (2015-01-03) [4384] Installing Cucumber on Ubuntu - cannot load such file -- mkmf (LoadError) message - (2015-01-04) [4386] Guide exercise to help you learn Gherkin, Cucumber and Rspec - (2015-01-06) [4551] Testing your new class - first steps with cucumber - (2015-10-23) [4552] Scenario outlines - tables of values to test - in Gherkin / Cucumber - (2015-10-23)
Some other Articles
A booking that looks too good to be true? It probably is too good to be true!Second step Cucumber and Gherkin - beyond Hello WorldWell House Consultants / Well House Manor - Prices for 2015What FGW passengers want to talk about / and PHP programming to find outDesigning a base class and subclasses, and their extension, in C++
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This is a page archived from The Horse's Mouth at
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