Ensuring good caching for the most popular pages. Added tests.

test/controllers/weight_show_cache_test.rb

@@ -0,0 +1,107 @@
+require "test_helper"
+
+class WeightShowCacheTest < ActionController::TestCase
+  tests WeightsController
+
+  setup do
+    create_a_tournament_with_single_weight("Regular Double Elimination 1-6", 8)
+    @tournament.update!(user_id: users(:one).id)
+    @weight = @tournament.weights.first
+
+    @original_perform_caching = ActionController::Base.perform_caching
+    ActionController::Base.perform_caching = true
+    Rails.cache.clear
+  end
+
+  teardown do
+    Rails.cache.clear
+    ActionController::Base.perform_caching = @original_perform_caching
+  end
+
+  test "weight show readonly row fragments hit cache and invalidate after wrestler update" do
+    first_events = cache_events_for_weight_show do
+      get :show, params: { id: @weight.id }
+      assert_response :success
+    end
+    assert_operator cache_writes(first_events), :>, 0, "Expected initial weight show render to write readonly row fragments"
+
+    second_events = cache_events_for_weight_show do
+      get :show, params: { id: @weight.id }
+      assert_response :success
+    end
+    assert_equal 0, cache_writes(second_events), "Expected repeat weight show render to reuse readonly row fragments"
+    assert_operator cache_hits(second_events), :>, 0, "Expected repeat weight show render to hit readonly row cache"
+
+    wrestler = @weight.wrestlers.first
+    third_events = cache_events_for_weight_show do
+      wrestler.touch
+      get :show, params: { id: @weight.id }
+      assert_response :success
+    end
+    assert_operator cache_writes(third_events), :>, 0, "Expected wrestler update to invalidate weight show readonly row cache"
+  end
+
+  test "weight show does not leak manage-only controls from cache across users" do
+    sign_in users(:one)
+    get :show, params: { id: @weight.id }
+    assert_response :success
+    assert_includes response.body, "Save Seeds"
+    assert_match(/fa-trash-alt/, response.body)
+    assert_match(/name="wrestler\[\d+\]\[original_seed\]"/, response.body)
+
+    sign_out
+
+    get :show, params: { id: @weight.id }
+    assert_response :success
+    assert_not_includes response.body, "Save Seeds"
+    assert_no_match(/fa-trash-alt/, response.body)
+    assert_no_match(/name="wrestler\[\d+\]\[original_seed\]"/, response.body)
+
+    spectator_cache_events = cache_events_for_weight_show do
+      get :show, params: { id: @weight.id }
+      assert_response :success
+    end
+    assert_operator cache_hits(spectator_cache_events), :>, 0, "Expected repeat spectator request to hit readonly wrestler row cache"
+    assert_not_includes response.body, "Save Seeds"
+    assert_no_match(/fa-trash-alt/, response.body)
+    assert_no_match(/name="wrestler\[\d+\]\[original_seed\]"/, response.body)
+  end
+
+  private
+
+  def sign_out
+    @request.session[:user_id] = nil
+    @controller.instance_variable_set(:@current_user, nil)
+    @controller.instance_variable_set(:@current_ability, nil)
+  end
+
+  def cache_events_for_weight_show
+    events = []
+    subscriber = lambda do |name, _start, _finish, _id, payload|
+      key = payload[:key].to_s
+      next unless key.include?("weight_show_wrestler_row")
+
+      events << { name: name, hit: payload[:hit] }
+    end
+
+    ActiveSupport::Notifications.subscribed(
+      subscriber,
+      /cache_(read|write|fetch_hit|generate)\.active_support/
+    ) do
+      yield
+    end
+
+    events
+  end
+
+  def cache_writes(events)
+    events.count { |event| event[:name] == "cache_write.active_support" }
+  end
+
+  def cache_hits(events)
+    events.count do |event|
+      event[:name] == "cache_fetch_hit.active_support" ||
+        (event[:name] == "cache_read.active_support" && event[:hit])
+    end
+  end
+end