A (Brief!) Intro to RSpec
Doug Price / @solipet
December 8, 2015
Components of RSpec
- rspec-core
describe, it, before, let, subject
- rspec-expectations
expect(book).to be_published
- rspec-mocks
- stubs, fakes, and message expectations
allow(post).to receive_messages( title: "Why RSpec?", author: doug)
- rspec-rails
Plus 283 other gems! Zomg!!!
rspec-core: ExampleGroup
- describe, context
-
Creates an ExampleGroup. Within the block passed to describe, you can declare examples using the it method.
You can also declare nested groups using the describe or context methods.
``` ruby
describe Post do
context "published" do
...
end
context "draft" do
...
end
end
```
rspec-core: Example
- it, specify, example
- Creates an Example. Within the block passed to describe, you can declare examples using the it method.
``` ruby
describe Post do
context "published" do
it "shows the date it was published" do
...
end
end
end
```
rspec-core: Hooks
- before, after, around
-
Methods to support common setup and teardown.
Available from any describe or context block, or off the configuration object to define global setup/teardown logic.
``` ruby
describe Post do
before do
@post = Post.new
end
it "starts as a draft" do
expect(@post.published).to be(false)
end
end
```
http://www.rubydoc.info/gems/rspec-core/RSpec/Core/Hooks#before-instance_method
rspec-core: MemoizedHelpers
- let
- Generates a method whose return value is memoized after the first call.
``` ruby
describe Post do
let(:post) { Post.new }
it "is awesome" do
expect(post).to be_awesome
end
end
```
rspec-core: MemoizedHelpers
- subject
- Declares a subject for an example group which can then be wrapped with expect using is_expected to make it the target of an expectation in a concise, one-line example.
``` ruby
describe Post do
subject { Post.new }
it { is_expected.to be_awesome }
end
```
Note: is_expected is defined in rspec-core, but only works if rspec-expectations is included!
rspec-expectations: Matchers
| Type | Example |
|---|---|
| Equivalance | `expect(actual).to eq(expected) # passes if actual == expected` |
| Identity | `expect(actual).to be(expected) # passes if actual.equal?(expected)` |
| Comparisons | `expect(actual).to be > expected` |
| Regular Expressions | `expect(actual).to match(/expression/)` |
| Types/classes | `expect(actual).to be_a(expected) # passes if actual.kind_of?(expected)` |
| Truthiness | `expect(actual).to be true # passes if actual == true` |
| Errors | `expect { ... }.to raise_error(ErrorClass, "message")` |
| Throws | `expect { ... }.to throw_symbol(:symbol, 'value')` |
| Yielding | `expect { |b| 5.tap(&b) }.to yield_control` |
| Predicate | `expect(actual).to be_xxx # passes if actual.xxx?` |
| Ranges | `expect(1..10).to cover(3)` |
| Collection | `expect(actual).to include(expected)` |
rspec-expectations: Should matchers
Starting in v2.11, the expect method was introduced and is now recommended. The older should syntax is still supported.
| Should | Expect |
|---|---|
| `actual.should eq(expected)` | `expect(actual).to eq(expected)` |
| `actual.should match(/expression/)` | `expect(actual).to match(/expression/)` |
rspec-rails: setup
``` bash
$ vim Gemfile
group :development, :test do
gem 'rspec-rails', '~> 3.0'
end
$ bundle install --binstubs
...
$ rails generate rspec:install
Looks like your app's ./bin/rails is a stub that was generated by Bundler.
In Rails 4, your app's bin/ directory contains executables that are versioned
like any other source code, rather than stubs that are generated on demand.
Here's how to upgrade:
bundle config --delete bin # Turn off Bundler's stub generator
rake rails:update:bin # Use the new Rails 4 executables
git add bin # Add bin/ to source control
You may need to remove bin/ from your .gitignore as well.
...
$ cat .rspec
--color
--require spec_helper
$ cat spec/spec_helper.rb
# This file was generated by the `rails generate rspec:install` command. Conventionally, all
# specs live under a `spec` directory, which RSpec adds to the `$LOAD_PATH`.
# The generated `.rspec` file contains `--require spec_helper` which will cause
# this file to always be loaded, without a need to explicitly require it in any
# files.
#
# Given that it is always loaded, you are encouraged to keep this file as
# light-weight as possible. Requiring heavyweight dependencies from this file
# will add to the boot time of your test suite on EVERY test run, even for an
# individual file that may not need all of that loaded. Instead, consider making
# a separate helper file that requires the additional dependencies and performs
# the additional setup, and require it from the spec files that actually need
# it.
#
# The `.rspec` file also contains a few flags that are not defaults but that
# users commonly want.
#
# See http://rubydoc.info/gems/rspec-core/RSpec/Core/Configuration
RSpec.configure do |config|
# rspec-expectations config goes here. You can use an alternate
# assertion/expectation library such as wrong or the stdlib/minitest
# assertions if you prefer.
config.expect_with :rspec do |expectations|
# This option will default to `true` in RSpec 4. It makes the `description`
# and `failure_message` of custom matchers include text for helper methods
# defined using `chain`, e.g.:
# be_bigger_than(2).and_smaller_than(4).description
# # => "be bigger than 2 and smaller than 4"
# ...rather than:
# # => "be bigger than 2"
expectations.include_chain_clauses_in_custom_matcher_descriptions = true
end
# rspec-mocks config goes here. You can use an alternate test double
# library (such as bogus or mocha) by changing the `mock_with` option here.
config.mock_with :rspec do |mocks|
# Prevents you from mocking or stubbing a method that does not exist on
# a real object. This is generally recommended, and will default to
# `true` in RSpec 4.
mocks.verify_partial_doubles = true
end
# The settings below are suggested to provide a good initial experience
# with RSpec, but feel free to customize to your heart's content.
=begin
# These two settings work together to allow you to limit a spec run
# to individual examples or groups you care about by tagging them with
# `:focus` metadata. When nothing is tagged with `:focus`, all examples
# get run.
config.filter_run :focus
config.run_all_when_everything_filtered = true
# Allows RSpec to persist some state between runs in order to support
# the `--only-failures` and `--next-failure` CLI options. We recommend
# you configure your source control system to ignore this file.
config.example_status_persistence_file_path = "spec/examples.txt"
# Limits the available syntax to the non-monkey patched syntax that is
# recommended. For more details, see:
# - http://rspec.info/blog/2012/06/rspecs-new-expectation-syntax/
# - http://www.teaisaweso.me/blog/2013/05/27/rspecs-new-message-expectation-syntax/
# - http://rspec.info/blog/2014/05/notable-changes-in-rspec-3/#zero-monkey-patching-mode
config.disable_monkey_patching!
# Many RSpec users commonly either run the entire suite or an individual
# file, and it's useful to allow more verbose output when running an
# individual spec file.
if config.files_to_run.one?
# Use the documentation formatter for detailed output,
# unless a formatter has already been configured
# (e.g. via a command-line flag).
config.default_formatter = 'doc'
end
# Print the 10 slowest examples and example groups at the
# end of the spec run, to help surface which specs are running
# particularly slow.
config.profile_examples = 10
# Run specs in random order to surface order dependencies. If you find an
# order dependency and want to debug it, you can fix the order by providing
# the seed, which is printed after each run.
# --seed 1234
config.order = :random
# Seed global randomization in this process using the `--seed` CLI option.
# Setting this allows you to use `--seed` to deterministically reproduce
# test failures related to randomization by passing the same `--seed` value
# as the one that triggered the failure.
Kernel.srand config.seed
=end
end
```
Running tests
``` bash
$ rake spec
$ rake spec:models
$ rake -T | grep spec
```
rspec-rails Spec Types
| Model | Used to describe behavior of models in the application. |
|---|---|
| Controller | Used to describe behavior of Rails controllers. |
| Feature | Used to test your application from the outside by simulating a browser. |
| Request | Used to specify one or more request/response cycles from end to end using a black box approach. |
| View | Used to test the rendering of your view templates. |
| Routing | Used to test the routes against controller actions. |
| Helper | Used to validate the behavior of helper methods. |