Rspec, TDD (1)

Nice to meet you. From April, I changed my job from the medical industry to a web engineer. Ruby experience is about 2 months.

It's been a month and a half since I joined the company, and in addition to minor corrections, I've been gradually developing new functions, and I'm feeling the growth little by little (I'm telling you that).

When developing a new function, I was told "Please write a test" and when I looked at the test code, I got a state of "I don't know how to write ...", so I gave priority to studying the test. I am. I somehow know (I think) under what conditions the test should be done, but I think it is necessary to get used to the notation peculiar to Rspec.

Currently, I am studying with reference to the following books and articles. Everyday Rails-Introduction to Rails Testing with RSpec Introduction to RSpec that can be used, Part 1 "Understanding the basic syntax and useful functions of RSpec" Test Driven Development

As a memorandum, I will leave the process of studying the test as an article little by little.

In the first place, if you can't trust the test you wrote, it won't start ...

What are the benefits of writing a test in the first place?

1. Cost reduction for the entire test

――By writing automated tests steadily, you can develop new functions while confirming that existing functions are working as expected. -You can guarantee that the original function is not destroyed when refactoring.

2. Become more resistant to changes in the environment

--You can investigate the impact when changing versions such as ruby, rails, and gem updates.

3. The test itself becomes a document of use

—— Helps others understand the specification as it represents the details of the expected behavior. --It will be an opportunity to reconsider the specifications and interface

4. Helps keep code granularity

--Methods and actions that are difficult to write tests have so many roles, which gives you an opportunity to rethink your implementation.

5. Improvement of overall development efficiency

――This is all. Development is much safer and more secure than manual testing and prayer deployment

Rspec setup

--Add to Gemfile because it is not included in Rails by default → bundle install

Gemfile


group :development, :test do
  gem 'rspec-rails', '~> 3.8.0'
end

--Creating a test DB

config/database.yml


test:
  <<: *default
  database: db/test.sqlite3

Run bin / rails db: create: all

Rspec settings

Run bin / rails g rspec: install The spec storage directory, helper file, and configuration file are created.

.rspec


--format documentation

If you add it, the output information will be easier to read.

--Install binstub and spring to improve Rspec test efficiency

About binstub About Spring

gemfile


group :development do
  gem 'spring-commands-rspec'
end

Run $ bundle exec spring binstub rspec Now you can run the test with $ bin / rspec

First check the basic syntax

--describe: Test grouping declaration, nestable --it: Organize tests into units called examples --expect (A) .to eq B: A test that expects A to be B

sample_spec.rb


Rspec.describe 'Calculation' do
  it '100 +100 is 200' do
   expect(100 + 100).to eq 200
  end
  it '100 *100 is 10000' do
    expect(100 * 100).to eq 10000
  end
end

--context: Group by condition --before: Data preparation and assets before test execution, which are always called before execution of example, are often performed. --Be careful when using variables because before and it have different scopes.

--let (: A) {B}: B can be referred to as A --let is lazy evaluation and will not be used until it is called --let !: The value defined before executing the example is created, this may be better when the test is failing due to lazy evaluation

--subject: Can group objects under test --In that case, use is_expected

--shared_example, it_behaves_like: Can be reused when example is not DRY

--shared_context, include_context: context can be reused

For the time being, this is the end. I understand the basics, so I will write more and more

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