Vanilla Rails Testing

Counter-intuitive patterns from 37signals. These are NOT standard Rails community practices.

Core principle: Fixtures over factories. Always. Integration tests for controllers. Minitest, not RSpec.

The Iron Law

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

If you write create(:model), FactoryBot, let, describe, it, expect, or before_each → DELETE IT.

Fixtures Only

ruby

# ✅ GOOD - Reference fixtures
test "close card" do
  cards(:logo).close
  assert cards(:logo).closed?
end

# ❌ BAD - Never create data
test "close card" do
  card = create(:card)  # DELETE THIS
  card.close
end

# ❌ BAD - Never use FactoryBot
let(:card) { create(:card) }  # DELETE THIS

# ❌ BAD - Never use RSpec
describe Card do  # DELETE THIS
  it "closes" do  # DELETE THIS

Reference fixtures by symbol: cards(:logo), users(:david), boards(:writebook), sessions(:kevin)

Why fixtures? They're real data, loaded once, fast, and force you to think about realistic scenarios.

Q: What if the fixture I need doesn't exist? A: Add it to the fixtures file. Never create data in tests.

Controller Tests Use Integration Style

ruby

# ✅ GOOD - ActionDispatch::IntegrationTest
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

# ❌ BAD - Never use ActionController::TestCase
class Cards::ClosuresControllerTest < ActionController::TestCase  # DELETE THIS
  post :create, params: { card_id: card.id }  # DELETE THIS
end

Why integration style? Tests the full request cycle including routing, middleware, and response rendering.

Model Tests Require Current.session

ruby

# ✅ GOOD - Set Current.session in setup
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

# ❌ BAD - Missing Current.session
class Card::CloseableTest < ActiveSupport::TestCase
  # Missing setup - tests may fail or behave incorrectly
  test "close records user" do
    cards(:logo).close(user: users(:kevin))
  end
end

Why Current.session? Models often rely on Current.session for user context, event recording, and authorization.

Always set it, even if you think it's not needed.

Simple Test Names

ruby

# ✅ GOOD - Concise, clear
test "create"
test "close records user"
test "reopen creates event"

# ❌ BAD - Verbose, repetitive
test "should create a new card when given valid parameters"
test "should mark the card as closed when user closes it"
it "should record the user who closed the card"  # Also wrong syntax

Why simple names? File and test method name provide enough context. No need to repeat.

Use Minitest Syntax

ruby

# ✅ GOOD - Minitest assertions
test "close" do
  assert cards(:logo).close
  assert cards(:logo).closed?
  assert_not cards(:shipping).open?
end

# ✅ GOOD - Exception testing
assert_raises ActiveRecord::RecordNotFound do
  Card.find("nonexistent")
end

# ❌ BAD - RSpec syntax
it "should close" do  # DELETE THIS
  expect(card.close).to be_truthy  # DELETE THIS
  expect(card.closed?).to be true  # DELETE THIS
end

# ❌ BAD - RSpec describe/context
describe "#close" do  # DELETE THIS
  context "when card is open" do  # DELETE THIS

Use: test, setup, assert, assert_equal, assert_not, assert_difference, assert_changes, assert_raises

NEVER use: it, describe, context, before_each, let, expect, refute (use assert_not instead)

assert_difference for State Changes

ruby

# ✅ GOOD - Single change with lambda syntax
assert_difference -> { Card.count }, +1 do
  post board_cards_path(boards(:writebook))
end

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

# ❌ BAD - RSpec expect/to change
expect {  # DELETE THIS
  card.close
}.to change { Event.count }.by(1)  # DELETE THIS

Why lambda syntax? Evaluates the expression in the block's context, capturing state changes correctly.

assert_changes for Boolean Toggles

ruby

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

# ❌ BAD - Manual before/after checks
closed_before = card.closed?  # Too verbose
card.close
assert_not_equal closed_before, card.reload.closed?

System Tests (Capybara)

System tests follow the same rules:

ruby

# ✅ GOOD - ApplicationSystemTestCase with fixtures
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

# ❌ BAD - Creating data in system tests
test "create a card" do
  user = create(:user)  # DELETE THIS
  sign_in_as(user)
end

Stubbing and Mocking

Use mocha for stubbing, webmock for HTTP requests:

ruby

# ✅ GOOD - Mocha for stubbing
TestMailer.stubs(:goes_boom).raises(Net::SMTPSyntaxError)

# ✅ GOOD - WebMock for HTTP
stub_request(:post, webhook.url).to_return(status: 200)

# ❌ BAD - RSpec mocks
allow(TestMailer).to receive(:goes_boom)  # DELETE THIS

Common Rationalizations (All Wrong)

Excuse	Reality
"FactoryBot is standard Rails practice"	Not in vanilla Rails. Fixtures only.
"RSpec is more expressive"	Minitest is simpler. Use it.
"Creating test data makes tests clearer"	Fixtures make tests realistic. No creation.
"ActionController::TestCase is for controllers"	Integration tests cover more. Use those.
"Current.session isn't needed here"	Models rely on it. Always set it.
"Verbose names document the test"	File name + method name = enough context.
"let makes setup DRY"	setup method does the same. No let.
"describe/context organizes tests"	Class and file organization is enough.
"I'll just create one record since fixture missing"	Add the fixture. Never create in tests.
"refute is more idiomatic Minitest"	Use assert_not for consistency.

Red Flags - STOP and Rewrite

Seeing any of these? DELETE THE CODE and start over:

create(:model), build(:model), or FactoryBot
let, describe, it, context, before_each, subject
expect(...).to or .should
ActionController::TestCase
Model test without Current.session = sessions(:fixture)
Test names starting with "should"
Data creation in tests (User.create, Card.new, Board.build)
refute (use assert_not)

Quick Reference

Pattern	Use	Never Use
Test framework	Minitest	RSpec
Test data	Fixtures (`cards(:logo)`)	Factories (`create(:card)`)
Controller tests	`ActionDispatch::IntegrationTest`	`ActionController::TestCase`
System tests	`ApplicationSystemTestCase`	Any other base class
Model setup	`Current.session = sessions(:david)`	Nothing (missing context)
Test blocks	`test "name"`	`it "should..."`, `describe`
Setup	`setup do`	`before_each`, `let`, `subject`
Assertions	`assert`, `assert_not`	`expect`, `should`, `refute`
Test names	`test "create"`	`it "should create..."`
Stubbing	`mocha` (`.stubs`)	RSpec mocks (`allow`, `expect`)
HTTP mocking	`webmock`	VCR, other tools

Real Example Comparison

❌ What NOT to Write (Common Mistakes)

ruby

require "rails_helper"

RSpec.describe Card, type: :model do
  let(:board) { create(:board) }
  let(:card) { create(:card, board: board) }
  let(:user) { create(:user) }

  describe "#close" do
    it "should mark card as closed when user closes it" do
      expect {
        card.close(user: user)
      }.to change { card.reload.closed? }.from(false).to(true)

      expect(card.closed_by).to eq(user)
    end

    context "when already closed" do
      let(:card) { create(:card, :closed) }

      it "should not create duplicate events" do
        expect {
          card.close(user: user)
        }.not_to change { Event.count }
      end
    end
  end
end

✅ What to Write (Vanilla Rails)

ruby

require "test_helper"

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

  test "close" do
    assert_not cards(:logo).closed?

    cards(:logo).close(user: users(:kevin))

    assert cards(:logo).closed?
    assert_equal users(:kevin), cards(:logo).closed_by
  end

  test "close creates event" do
    assert_difference -> { cards(:logo).events.count }, +1 do
      cards(:logo).close(user: users(:kevin))
    end
  end
end

The Bottom Line

Vanilla Rails is deliberately simple:

Fixtures, not factories
Integration tests, not controller unit tests
Minitest, not RSpec
Current.session for model tests
Simple names, minimal ceremony
Always use fixtures, even if you need to create new ones

If the Rails community does it differently, that's fine. We don't.

Follow these patterns exactly. No exceptions, no "better" alternatives.

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SKILL.md

Vanilla Rails Testing

The Iron Law

Fixtures Only

Controller Tests Use Integration Style

Model Tests Require Current.session

Simple Test Names

Use Minitest Syntax

assert_difference for State Changes

assert_changes for Boolean Toggles

System Tests (Capybara)

Stubbing and Mocking

Common Rationalizations (All Wrong)

Red Flags - STOP and Rewrite

Quick Reference

Real Example Comparison

❌ What NOT to Write (Common Mistakes)

✅ What to Write (Vanilla Rails)

The Bottom Line