Don't load AR integration if it is unavailable (#188)

When writing tests for a project that uses certain parts of Rails, it
should still be possible to say `require "super_diff/rails"`, and
SuperDiff should only load the integrations that correspond to the
available parts. Right now the only two integrations are ActiveSupport
and ActiveRecord. ActiveSupport should always be available, but
ActiveRecord may not be available, so this commit adds a guard around
that integration in particular. It also adds tests for Combustion so we
can test that this guard specifically works for engines where
ActiveRecord is not being loaded.

Co-authored-by: Harry Lascelles <harry@harryl.com>
Co-authored-by: sshaw <skye.shaw@gmail.com>

.gitignore

@@ -5,6 +5,7 @@ gemfiles/*.gemfile.lock
 node_modules
 pkg
 spec/examples.txt
+spec/internal
 tmp
 zeus.server.log
 zeus.server-start.log

Appraisals

@@ -3,31 +3,29 @@ rails_dependencies =
     gem "activerecord-jdbcsqlite3-adapter", platform: :jruby
     gem "jdbc-sqlite3", platform: :jruby
     gem "net-ftp"
+    gem "combustion"
   end
 
 appraisals = {
   rails_6_0:
     proc do
       instance_eval(&rails_dependencies)
 
-      gem "activerecord", "~> 6.0.0"
-      gem "railties", "~> 6.0.0"
+      gem "rails", "~> 6.0.0"
       gem "sqlite3", "~> 1.4.0", platform: %i[ruby mswin mingw]
     end,
   rails_6_1:
     proc do
       instance_eval(&rails_dependencies)
 
-      gem "activerecord", "~> 6.1.0"
-      gem "railties", "~> 6.1.0"
+      gem "rails", "~> 6.1.0"
       gem "sqlite3", "~> 1.4.0", platform: %i[ruby mswin mingw]
     end,
   rails_7_0:
     proc do
       instance_eval(&rails_dependencies)
 
-      gem "activerecord", "~> 7.0.0"
-      gem "railties", "~> 7.0.0"
+      gem "rails", "~> 7.0.0"
       gem "sqlite3", "~> 1.4.0", platform: %i[ruby mswin mingw]
     end,
   no_rails: proc {},

gemfiles/rails_6_0_rspec_gte_3_10.gemfile

@@ -17,8 +17,8 @@ gem "warnings_logger"
 gem "activerecord-jdbcsqlite3-adapter", platform: :jruby
 gem "jdbc-sqlite3", platform: :jruby
 gem "net-ftp"
-gem "activerecord", "~> 6.0.0"
-gem "railties", "~> 6.0.0"
+gem "combustion"
+gem "rails", "~> 6.0.0"
 gem "sqlite3", "~> 1.4.0", platform: [:ruby, :mswin, :mingw]
 gem "rspec", ">= 3.10", "< 4"
 gem "rspec-rails"

gemfiles/rails_6_0_rspec_lt_3_10.gemfile

@@ -17,8 +17,8 @@ gem "warnings_logger"
 gem "activerecord-jdbcsqlite3-adapter", platform: :jruby
 gem "jdbc-sqlite3", platform: :jruby
 gem "net-ftp"
-gem "activerecord", "~> 6.0.0"
-gem "railties", "~> 6.0.0"
+gem "combustion"
+gem "rails", "~> 6.0.0"
 gem "sqlite3", "~> 1.4.0", platform: [:ruby, :mswin, :mingw]
 gem "rspec", "~> 3.9.0"
 gem "rspec-rails"

gemfiles/rails_6_1_rspec_gte_3_10.gemfile

@@ -17,8 +17,8 @@ gem "warnings_logger"
 gem "activerecord-jdbcsqlite3-adapter", platform: :jruby
 gem "jdbc-sqlite3", platform: :jruby
 gem "net-ftp"
-gem "activerecord", "~> 6.1.0"
-gem "railties", "~> 6.1.0"
+gem "combustion"
+gem "rails", "~> 6.1.0"
 gem "sqlite3", "~> 1.4.0", platform: [:ruby, :mswin, :mingw]
 gem "rspec", ">= 3.10", "< 4"
 gem "rspec-rails"

gemfiles/rails_6_1_rspec_lt_3_10.gemfile

@@ -17,8 +17,8 @@ gem "warnings_logger"
 gem "activerecord-jdbcsqlite3-adapter", platform: :jruby
 gem "jdbc-sqlite3", platform: :jruby
 gem "net-ftp"
-gem "activerecord", "~> 6.1.0"
-gem "railties", "~> 6.1.0"
+gem "combustion"
+gem "rails", "~> 6.1.0"
 gem "sqlite3", "~> 1.4.0", platform: [:ruby, :mswin, :mingw]
 gem "rspec", "~> 3.9.0"
 gem "rspec-rails"

gemfiles/rails_7_0_rspec_gte_3_10.gemfile

@@ -17,8 +17,8 @@ gem "warnings_logger"
 gem "activerecord-jdbcsqlite3-adapter", platform: :jruby
 gem "jdbc-sqlite3", platform: :jruby
 gem "net-ftp"
-gem "activerecord", "~> 7.0.0"
-gem "railties", "~> 7.0.0"
+gem "combustion"
+gem "rails", "~> 7.0.0"
 gem "sqlite3", "~> 1.4.0", platform: [:ruby, :mswin, :mingw]
 gem "rspec", ">= 3.10", "< 4"
 gem "rspec-rails"

gemfiles/rails_7_0_rspec_lt_3_10.gemfile

@@ -17,8 +17,8 @@ gem "warnings_logger"
 gem "activerecord-jdbcsqlite3-adapter", platform: :jruby
 gem "jdbc-sqlite3", platform: :jruby
 gem "net-ftp"
-gem "activerecord", "~> 7.0.0"
-gem "railties", "~> 7.0.0"
+gem "combustion"
+gem "rails", "~> 7.0.0"
 gem "sqlite3", "~> 1.4.0", platform: [:ruby, :mswin, :mingw]
 gem "rspec", "~> 3.9.0"
 gem "rspec-rails"

lib/super_diff/rails.rb

@@ -1 +1,2 @@
-require "super_diff/active_record"
+require "super_diff/active_support"
+require "super_diff/active_record" if defined?(ActiveRecord)

spec/integration/rails/engines_spec.rb

@@ -0,0 +1,20 @@
+require "spec_helper"
+
+RSpec.describe "Integration with Rails engines", type: :integration do
+  context "when ActiveRecord is not loaded via Combustion" do
+    it "does not fail to load" do
+      as_both_colored_and_uncolored do |color_enabled|
+        program =
+          make_rspec_rails_engine_program(
+            "expect(true).to be(true)",
+            combustion_initialize: [:action_controller],
+            color_enabled: color_enabled
+          )
+
+        expect(program).not_to produce_output_when_run(
+          "uninitialized constant ActiveRecord"
+        ).in_color(color_enabled)
+      end
+    end
+  end
+end

spec/support/integration/helpers.rb

@@ -32,6 +32,18 @@ def make_rspec_rails_test_program(test, color_enabled:)
       TestPrograms::RSpecRails.new(test, color_enabled: color_enabled)
     end
 
+    def make_rspec_rails_engine_program(
+      test,
+      color_enabled:,
+      combustion_initialize:
+    )
+      TestPrograms::RspecRailsEngine.new(
+        test,
+        color_enabled: color_enabled,
+        combustion_initialize: combustion_initialize
+      )
+    end
+
     def build_expected_output(
       color_enabled:,
       snippet:,

spec/support/integration/matchers/produce_output_when_run_matcher.rb

@@ -55,6 +55,12 @@ def failure_message
         end
       end
 
+      def failure_message_when_negated
+        "Expected output of test not to produce output, but it did.\n\n" +
+          "Actual output:\n\n" +
+          SuperDiff::Test::OutputHelpers.bookended(actual_output)
+      end
+
       private
 
       attr_reader :expected_output, :program, :output_processor

spec/support/integration/test_programs/base.rb

@@ -112,7 +112,6 @@ def program
                 color_enabled: #{color_enabled?.inspect},
                 configuration: #{configuration.inspect}
               )
-              test_plan.boot
               #{test_plan_prelude}
               test_plan.#{test_plan_command}
 

spec/support/integration/test_programs/plain.rb

@@ -4,6 +4,12 @@ module TestPrograms
       class Plain < Base
         protected
 
+        def test_plan_prelude
+          <<~PRELUDE.strip
+            test_plan.boot
+          PRELUDE
+        end
+
         def test_plan_command
           "run_plain_test"
         end

spec/support/integration/test_programs/rspec_active_record.rb

@@ -5,7 +5,10 @@ class RSpecActiveRecord < Base
         protected
 
         def test_plan_prelude
-          "test_plan.boot_active_record"
+          <<~PRELUDE.strip
+            test_plan.boot
+            test_plan.boot_active_record
+          PRELUDE
         end
 
         def test_plan_command

spec/support/integration/test_programs/rspec_active_support.rb

@@ -5,7 +5,10 @@ class RSpecActiveSupport < Base
         protected
 
         def test_plan_prelude
-          "test_plan.boot_active_support"
+          <<~PRELUDE.strip
+            test_plan.boot
+            test_plan.boot_active_support
+          PRELUDE
         end
 
         def test_plan_command

spec/support/integration/test_programs/rspec_rails.rb

@@ -5,7 +5,10 @@ class RSpecRails < Base
         protected
 
         def test_plan_prelude
-          "test_plan.boot_active_record"
+          <<~PRELUDE.strip
+            test_plan.boot
+            test_plan.boot_active_record
+          PRELUDE
         end
 
         def test_plan_command

spec/support/integration/test_programs/rspec_rails_engine.rb

@@ -0,0 +1,30 @@
+module SuperDiff
+  module IntegrationTests
+    module TestPrograms
+      class RspecRailsEngine < Base
+        def initialize(*args, combustion_initialize:, **options)
+          super(*args, **options)
+          @combustion_initialize = combustion_initialize
+        end
+
+        protected
+
+        def test_plan_prelude
+          <<~PRELUDE.strip
+            test_plan.boot_rails_engine(
+              combustion_initialize: #{combustion_initialize.inspect}
+            )
+          PRELUDE
+        end
+
+        def test_plan_command
+          "run_rspec_rails_test"
+        end
+
+        private
+
+        attr_reader :combustion_initialize
+      end
+    end
+  end
+end

support/test_plan.rb

@@ -110,6 +110,11 @@ def boot_rails
     boot_active_record
   end
 
+  def boot_rails_engine(combustion_initialize: [])
+    require "combustion"
+    Combustion.initialize!(*combustion_initialize)
+  end
+
   def run_plain_test
     run_test_with_libraries("super_diff/rspec")
   end

zeus.json

@@ -12,6 +12,7 @@
       "boot_rails": {
         "run_rspec_rails_test": []
       }
-    }
+    },
+    "boot_rails_engine": []
   }
 }