Fundamentals of TDD - upcase

https://thoughtbot.com/upcase/fundamentals-of-tdd

Good reading: thoughtbot guidelines for testing with RSpec

Fundamentals of TDD - Overview

Red-Green-Refactor by Example

Telling a Story with Your Tests

https://thoughtbot.com/upcase/videos/telling-a-story-with-your-tests

Four Phases of Testing

Setup: get the conditions correct for the test
Exercise: perform the thing that you're testing
Verification: verify that the exercise did what you expected
Teardown: undo any conditions that shouldn't persist post-test

In this lesson it was mentioned that the test code should "tell a story", so it can work as documentation. Therefore, trying to DRY in test code can be a bad-practice.

Important

DRY is a good principle to follow in code, but it's a means to an end, not the end itself. Often in tests, overly-aggressive de-duplication can lower the quality of test code, as it loses its explanatory capability.

According to this article from thoughtbot, it's better to favor Ruby methods over RSpec's DSL constructs. Example:

describe "#promote_to_admin" do
  it "makes a regular membership an admin membership" do
    # setup
    membership_to_promote = build_non_admin_membership

    # exercise
    membership_to_promote.promote_to_admin

    # verify
    expect(membership_to_promote).to be_admin
  end

  it "doesn't change other memberships" do
    membership_to_promote = build_non_admin_membership
    membership_to_not_promote = build_non_admin_membership

    membership_to_promote.promote_to_admin

    expect(membership_to_not_promote).not_to be_admin
  end

  def build_non_admin_membership
    user = User.new
    group = Group.new("A group")

    Membership.new(user: user, group: group, admin: false)
  end
end