The Computer Is Always Right

The other day I had trouble getting a Cucumber scenario to work. Here’s what happened, partly to have a post I can come back to, when (!) my future self runs into a similar problem.

I am using Cucumber and a very stripped down version of the project looked like this:

% tree
.
└── features
    ├── example.feature
    ├── step_definitions
    │   └── step_def.rb
    └── support
        └── env.rb

All code is entirely contrived and tailored to demonstrate the issue I bumped into. The example file features/example.feature first:

Feature: What is happening?

Scenario Outline: Matching step definitions -- or not

Given a step that mentions '<a_string>'
And another step that uses <a_number> like this
Then all is good

Examples:
|  a_string |  a_number |
|      word |        42 |
| two words | 3.1415927 |

There are very plain step definitions too (in file step_definitions/step_def.rb):

Given("a step that mentions {string}") do |string|
  pending # Write code here …
end

Given(/another step that uses1 like this/) do |number|
  pending # Write code here …
end

Then("all is good") do
  pending # Write code here …
end

Running this gives the expected result: Cucumber kindly informs that there are pending steps:

% bundle exec cucumber
Feature: What is happening?

  Scenario Outline: Matching step definitions -- or not # features/example.feature:3
    Given a step that mentions '<a_string>'             # features/example.feature:5
    And another step that uses <a_number> like this     # features/example.feature:6
    Then all is good                                    # features/example.feature:7

    Examples:
      | a_string   | a_number  |
      | word       | 42        |
      | two words  | 3.1415927 |

2 scenarios (2 pending)
6 steps (4 skipped, 2 pending)
0m0.012s

However at some point, I started getting another result (comments added by cucumber removed):

% bundle exec cucumber
Feature: What is happening?

  Scenario Outline: Matching step definitions -- or not
    Given a step that mentions '<a_string>'
    And another step that uses <a_number> like this
    Then all is good

    Examples:
      | a_string   | a_number  |
      | word       | 42        |
      | two words  | 3.1415927 |

2 scenarios (2 undefined)
6 steps (4 skipped, 2 undefined)
0m0.009s

You can implement step definitions for undefined steps with these snippets:

Given("a step that mentions {string}") do |string|
  pending # Write code here that turns the phrase above into concrete actions
end

Wait. What?!? I stared at the existing step definition for a while, comparing it with the one printed in the message above:

Given("a step that mentions {string}") do |string|
  pending # Write code here …
end

Confusion and disbelief kicked in.

One of the principles I use is this:

The computer is always right.

— Not sure where I picked this up. If you know the (or a) source, tell me please.

This is true even if the behaviour is wrong. In this case: If cucumber cannot find a step definition … it CANNOT find a step definition. But why would that be? Why did it happen in this particular case?

I even called in colleagues (remotely) and we stared at the code collectively. Still nothing.

Luckily a trace of a previous successful run was still available in the console output. So I copy-and-pasted the scenarios, and compared them piece by piece in a Pry session:

% pry
[1] pry(main)> works = File.read 'features/works.feature'
=> "Feature: …"
[2] pry(main)> broken = File.read 'features/broken.feature'
=> "Feature: …"
[3] pry(main)> works == broken
=> false

So there is in fact a difference. But what? Where?
Using the same pry session we found out:

[4] pry(main)> works.each_codepoint.zip(broken.each_codepoint).select{|el| el[0] != el[1] }
=> [
    [0] [
        [0] 32,
        [1] 160
    ]
]

What this does: The codepoints of both strings are combined in pairs, and then the pairs that are different are selected. Here’s what the Ruby Documentation says about each_codepoint:

Passes the Integer ordinal of each character in str, also known as a codepoint when applied to Unicode strings to the given block. For encodings other than UTF-8/UTF-16(BE|LE)/UTF-32(BE|LE), values are directly derived from the binary representation of each character. If no block is given, an enumerator is returned instead.

“hello\u0639”.each_codepoint {|c| print c, ‘ ‘ }

produces:

104 101 108 108 111 1593

https://ruby-doc.org/core-2.7.1/String.html#method-i-each_codepoint

The small piece that changed the behaviour was a space, just not a ‘normal’ space, but a NO-BREAK SPACE (see, for example, https://en.wikipedia.org/wiki/Non-breaking_space for more about this topic).

Lessons I learned (again):

  1. Some problems are hard to see, and in this case it was even invisible.
  2. The message was correct: The step was not defined, it only looked (to the human eye) as if it was.
  3. Using <spacebar> gives a different result than <option>-<sapacebar>.

  1. \d+)|(\d+\.\d+ []

Writing a Ruby Related book(let) on LeanPub

I wrote “Fast Feedback Using Ruby” using LeanPub. The original version was published back in 2015. Since I’m updating it to cover the most recent (at the time of this writing) Ruby 2.7 and RubyGem versions. I figured, it’s a good idea to leave a trace of my workflow and setup. 🙂

My workflow look like this:

  1. Edit Text (or image) file
  2. Save file to local disk
  3. Commit to local Git repository
  4. Push to GitHub
  5. Generate preview PDF on LeanPub using a (post push) web hook
  6. Have Leanpub automatically push files to Dropbox
  7. Have Dropbox synchronise PDF file to local folder
  8. Restart at 1
Writing workflow using LeanPub, GitHub and Dropbox

Whenever I push changes to GitHub, a new preview of the book is generated and sent to my computer. This means I get frequent and fast feedback about how the newly written text looks.

This nicely fits my working preferences and it also matches the topic of this particular book.

Looking For A New Project

It’s time to find a new project!

What I’m looking for is a role as an agile software tester in a team that really strives to improve on agile techniques in both, testing and programming. I’m interested in learning more about DevOps, continuous delivery and automation, including but not limited to test automation.

Travelling in Northern Germany or Denmark is fine and a possibility to work (partially) remote would be lovely.

Technically, a project using Ruby and/or Rails would be fantastic. In case the team is working on steps to also use Elixir, that would be a bonus.

More about my previous work is available over at ‘work with me‘ as well as on my Xing profile.

Looking for a New Project

Exciting times: It’s time to find a new project!

What I’m looking for is a role as a software tester in a team that really strives to improve on agile techniques in both, testing and programming. I’m interested in learning more about DevOps, continuous delivery and automation, including but not limited to test automation.

What I’d prefer is a project, that allows — or expects — remote work. Travelling in Northern Germany or Denmark every other week is fine.

Technically, a project using Ruby and/or Rails would be fantastic. In case the team is working on steps to also use Elixir, that would be a bonus.

A caveat: My availability in November is limited, due to a keynote I’ll give at the Agile Testing Days.

More about my previous work is available over at ‘work with me‘ as well as on my Xing profile.

Announcement: Workshop & ebook: “Fast Feedback Using Ruby”

At the “London Tester Gathering Workshops 2015” (also see #LTGWorkshops on Twitter) I offer a workshop “Fast Feedback Loops & Fun with Ruby”. For this, I wanted to give attendees a handout, to make applying the stuff covered easier and it was planned to be a list of brief recipes.
Suffice to say that the handout grew (and it’s entirely possible that this is ‘feature creep’ in action). In fact, it grew to the point that I decided to turn it into an ebook. The book is not done yet, there’s some copy editing to do.

Fast Feedback Using Ruby

In any case: There will be an ebook, and it will be available on LeanPub at https://leanpub.com/fastfeedbackusingruby/. If you’re interested, please leave a note on the book’s pages.

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