Allow enabling/disabling IronTrail in rspec

.github/workflows/test.yml

@@ -60,7 +60,8 @@ jobs:
         POSTGRES_HOST: localhost
         POSTGRES_PORT: 5432
     - name: Run specs
-      run: bundle exec rake install_database_yml spec
+      run:
+        bundle exec rake install_database_yml spec && bundle exec rake testing_spec
       env:
         BACKTRACE: 1
         BUNDLE_GEMFILE: gemfiles/${{ matrix.gemfile }}.gemfile

README.md

@@ -70,6 +70,32 @@ RSpec.configure do |config|
 end
 ```
 
+You'll likely also want to require [lib/iron_trail/testing/rspec.rb](lib/iron_trail/testing/rspec.rb)
+in your `rails_helper.rb`, then explicitly either disable or enable IronTrail in tests:
+
+```ruby
+require 'iron_trail/testing/rspec'
+IronTrail::Testing.enable! # to have it enabled by default in specs
+IronTrail::Testing.disable! # to have it disabled by default in specs
+```
+
+You you don't make it explicit, IronTrail will be enabled by default, which will
+likely impact your test suite performance slightly.
+
+In case you disable it by default, you can enable it per rspec context with:
+
+```ruby
+describe 'in a "describe" block', iron_trail: true do
+  it 'or also in an "it" block', iron_trail: true do
+    # ...
+  end
+end
+```
+
+Enabling/disabling IronTrail in specs works by replacing the trigger function in Postgres
+with a dummy no-op function or with the real function and it won't add or drop triggers from
+any tables.
+
 ## Rake tasks
 
 IronTrail comes with a few handy rake tasks you can use in your dev, test and

Rakefile

@@ -75,4 +75,12 @@ require 'rspec/core/rake_task'
 task(:spec).clear
 RSpec::Core::RakeTask.new(:spec)
 
-task default: %i[prepare spec]
+# Loading the testing/rspec file will affect RSpec globally. Because of that,
+# we want to test it in a separate scope. We could also always require it,
+# but that wouldn't be true in a real rails app and could make all tests
+# farther apart from reality, thus less reliable.
+RSpec::Core::RakeTask.new(:testing_spec).tap do |task|
+  task.pattern = 'spec/testing_itself.rb'
+end
+
+task default: %i[prepare spec testing_spec]

lib/iron_trail/testing/rspec.rb

@@ -1,3 +1,44 @@
 # frozen_string_literal: true
 
 require 'iron_trail'
+
+module IronTrail
+  module Testing
+    class << self
+      attr_accessor :enabled
+
+      def enable!
+        DbFunctions.new(ActiveRecord::Base.connection).install_functions
+        @enabled = true
+      end
+
+      def disable!
+        # We "disable" it by replacing the trigger function by a no-op one.
+        # This should be faster than adding/removing triggers from several
+        # tables every time.
+        sql = <<~SQL
+          CREATE OR REPLACE FUNCTION irontrail_log_row()
+          RETURNS TRIGGER AS $$
+          BEGIN
+            RETURN NULL;
+          END;
+          $$ LANGUAGE plpgsql;
+        SQL
+
+        ActiveRecord::Base.connection.execute(sql)
+        @enabled = false
+      end
+    end
+  end
+end
+
+RSpec.configure do |config|
+  config.around(:each, iron_trail: true) do |example|
+    enabled = IronTrail::Testing.enabled
+    IronTrail::Testing.enable! unless enabled
+
+    example.run
+  ensure
+    IronTrail::Testing.disable! unless enabled
+  end
+end

spec/testing_itself.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+require 'iron_trail/testing/rspec'
+
+IronTrail::Testing.disable!
+
+RSpec.describe 'lib/iron_trail/testing/rspec.rb' do
+  let(:person) { Person.create!(first_name: 'Arthur', last_name: 'Schopenhauer') }
+
+  subject(:do_some_changes!) do
+    person.update!(first_name: 'Jim')
+    person.update!(first_name: 'Jane')
+  end
+
+  context 'with IronTrail disabled' do
+    it 'does not track anything' do
+      do_some_changes!
+
+      expect(person.reload.iron_trails.length).to be(0)
+    end
+  end
+
+  context 'with IronTrail enabled through the helper', iron_trail: true do
+    it 'does not track anything' do
+      do_some_changes!
+
+      expect(person.reload.iron_trails.length).to be(3)
+    end
+  end
+end