Vanilla Rails Testing

NO FACTORYBOT. NO RSPEC. NO DATA CREATION IN TESTS.

Banned → Required

Never use	Use instead
create(:model), build(:model), FactoryBot	Fixtures: cards(:logo)
let, describe, it, context, subject	test "name", setup do
expect(...).to, .should	assert, assert_equal, assert_not
refute	assert_not
ActionController::TestCase	ActionDispatch::IntegrationTest
before_each	setup do
RSpec mocks (allow, expect)	Mocha (.stubs)

If any banned pattern appears, delete it and rewrite.

Fixtures Only

test "close card" do
  cards(:logo).close
  assert cards(:logo).closed?
end

Fixture missing? Add it to the fixtures file. Never create data in tests.

Controller Tests = Integration Tests

class Cards::ClosuresControllerTest < ActionDispatch::IntegrationTest
  setup do
    sign_in_as :kevin
  end

  test "create" do
    post card_closure_path(cards(:logo)), as: :turbo_stream
    assert_response :success
  end
end

Model Tests Require Current.session

Always set Current.session in setup, even if you think it's not needed:

class Card::CloseableTest < ActiveSupport::TestCase
  setup do
    Current.session = sessions(:david)
  end

  test "close records user" do
    cards(:logo).close(user: users(:kevin))
    assert_equal users(:kevin), cards(:logo).closed_by
  end
end

Assertion Patterns

State changes: assert_difference with lambda syntax:

assert_difference -> { Card.count }, +1 do
  post board_cards_path(boards(:writebook))
end

assert_difference({
  -> { cards(:logo).events.count } => +1,
  -> { Event.count } => +1
}) do
  cards(:logo).close(user: users(:kevin))
end

Boolean toggles: assert_changes:

assert_changes -> { cards(:logo).reload.closed? }, from: false, to: true do
  post card_closure_path(cards(:logo)), as: :turbo_stream
end

Exceptions: assert_raises:

assert_raises ActiveRecord::RecordNotFound do
  Card.find("nonexistent")
end

Test Names

Concise. File + method name provide context.

# Good
test "create"
test "close records user"

# Bad
test "should create a new card when given valid parameters"

System Tests

Same rules — fixtures, no data creation:

class SmokeTest < ApplicationSystemTestCase
  test "create a card" do
    sign_in_as(users(:david))
    visit board_url(boards(:writebook))
    click_on "Add a card"
  end
end

Stubbing

Use mocha for stubs, webmock for HTTP:

TestMailer.stubs(:goes_boom).raises(Net::SMTPSyntaxError)
stub_request(:post, webhook.url).to_return(status: 200)

Red Flags

Red flag	Action
create(:model) or FactoryBot	Delete. Use fixtures.
describe, it, context	Delete. Use test.
expect(...).to	Delete. Use assert.
Model test without Current.session	Add Current.session = sessions(:fixture)
Test names starting with "should"	Shorten.
Data creation in tests	Add fixture instead.