William Liu

Ruby Rspec Tests

RSpec is a testing tool for Ruby to create behavior-driven development (BDD). RSpec is made up of multiple libraries that are designed to work together or can be used independently with other testing tools like Cucumber or Minitest. The parts are:

rspec-core - the spec runner, which provides a command line program, flexible and customizable reporting, and an API to organize your code examples.
rspec-expectations - provides a readable API to express expected outcomes of a code example
rspec-mocks - test double framework, providing multiple types of fake objects to allow you to tightly control the environment in which your specs run
rspec-rails - supports using rspec to test Ruby on Rails applications in place of Rails’ built-in test framework

Relish

RSpec is documented through executable examples on Relish: http:relishapp.com/rspec

The examples are written in an “end-to-end” style demonstrating the use of various RSpec features in the context of executable spec files. If you want detailed documentation about a particular API or feature, use the API docs instead.

Cucumber

Cucumber provides executable documentation and provides reports indicating whether the software behaves according to the specification or not.

Test Driven Development (TDD)

BDD’s parent is test-driven development (TDD), which means we work in a red-green loop for writing small tests so that the test initially fails, then passes after writing our code.

Behavior Driven Development (BDD)

BDD is a concept build on top of TDD, where we write tests as specifications of system behavior. With RSpec, we are describing the behavior of classes, modules, and their methods.

Tests are called specs (specifications)
Tests are stored in a spec directory

Run specs with bundle exec rspec

Code coverage with Simplecov

https://github.com/colszowka/simplecov

Install the simplecov gem, then add SimpleCov to the top of your spec_helper.rb file.

require 'simplecov'
SimpleCov.start

You should then get a directory called coverage with your results

One thing to note is that you want to put SimpleCov above everything else. For example, if you have some code require 'mycode' that you want covered, make sure that require 'simplecov' and SimpleCov.start is above your other require.

Describing Methods

So RSpec is a behavior-driven development process of writing human readable specifications. The basic structure is that Rspec uses the words describe and it so we can express concepts like a conversation:

`describe` and `it`

“Describe an order.”
“It sums the prices of its line items.”

`describe` and `context`

describe and context group related tests together They are the same method.

So when do you use describe and when do you use context?

Use describe for things
Use context for states

Bad: context "#matriculate" Better:describe “#matriculate”

Bad: describe "when the student is sick" Better: context "when the student is sick"

`context`

Prefer context since tests usually deal with permutations of state
context names should not match your method names
Explain why a user would call the method

Example:

Bad: describe "#assign" Better: context "assigning homework to a student"

Nested Groups with `describe` and/or `context`

RSpec has two scopes:

Example Group are groups defined by a describe or context block
Example are typically defined by an it block, which are evaluated in the context of an instance of the example group class to which the example belongs.

Example of a nested group:

RSpec.describe Order do
  context "with no items" do
    it "behaves one way" do
      # ...
    end
  end

  context "with one item" do
    it "behaves another way" do
      # ...
    end
  end
end

`before` vs `let`

before eagerly runs code before each test let lazily runs code when it is first used

Use before for actions Use let for dependencies (real or test double)

Examples:

Bad: let(:dummy) do @classroom.initialize_roster end Better: before do @classroom.initialize_roster end

Bad: before { @grade_levels = [1, 2, 3] } Better: let(:grade_levels) { [1, 2, 3] }

`before` with `context`

context is used for state
before lists the actions to get to that state

Remove weak words

Don’t use “should” in your test names
Say what will happen
Running the test will tell you if it is true or not
Prefer active verbs as in “France beat Brazil in the finals.”
Do not use passive verbs as in “Brazil was beaten by France in the finals”

Bad: it “should add the student to the class” Better: it “adds the student to the class”

Sources

http://www.betterspecs.org/ https://github.com/rubocop-hq/rspec-style-guide http://jakegoulding.com/presentations/rspec-structure/#slide-1

Ruby Rspec Tests

Relish

Cucumber

Test Driven Development (TDD)

Behavior Driven Development (BDD)

Code coverage with Simplecov

Describing Methods

describe and it

describe and context

context

Nested Groups with describe and/or context

before vs let

before with context