rails-testing

Rails Testing Skill

Testing strategy for Rails applications using Minitest and fixtures. Not RSpec, not FactoryBot.

Sub-files:

• FIXTURES.md — Fixture patterns and test data management
• SYSTEM-TESTS.md — System and integration test conventions

---

Philosophy

• Test at the model level first — Business logic lives in models; that's where tests provide the most value
• Fixtures over factories — YAML fixtures are deterministic, fast, and require no setup code
• Always set Current.session — Lambda defaults and multi-tenancy depend on it; forgetting it is the #1 test failure
• Test behavior, not implementation — Assert on outcomes, not internal method calls
• Use assert_difference for state changes — Catches false positives that boolean checks alone miss

---

File Organization

test/
  models/
    card/
      archivable_test.rb    # Concern tests get their own file
    card_test.rb
  controllers/
    cards/
      closures_controller_test.rb
  jobs/
    notify_recipients_job_test.rb
  fixtures/
    cards.yml
    sessions.yml

---

Standard Test Structure

require "test_helper"

class Card::CloseableTest < ActiveSupport::TestCase
  setup do
    Current.session = sessions(:david)  # Always — sets user + account context
  end

  test "close creates closure record and marks card closed" do
    card = cards(:logo)

    assert_difference -> { Closure.count }, +1 do
      card.close
    end

    assert card.closed?
  end
end

---

Model Testing

State Changes

Nest assert_difference blocks when multiple record types change together:

assert_difference -> { Closure.count }, +1 do
  assert_difference -> { Event.count }, +1 do
    card.close
  end
end

assert card.closed?
assert_equal "card_closed", Event.last.action

Event Attributes

Count alone is insufficient — always verify attributes:

event = Event.last
assert_equal "card_archived", event.action
assert_equal card, event.eventable
assert_equal Current.user, event.creator
# For events with particulars:
assert_equal old_board.name, event.particulars["old_board"]