Add Rails/PersistenceCalledOutsideExample cop.

CHANGELOG.md

@@ -8,6 +8,7 @@
 * Add `IgnoredMetadata` configuration option to `RSpec/DescribeClass`. ([@Rafix02][])
 * Fix false positives in `RSpec/EmptyExampleGroup`. ([@pirj][])
 * Fix a false positive for `RSpec/EmptyExampleGroup` when example is defined in an `if` branch. ([@koic][])
+* Add RSpec/Rails/PersistenceCalledOutsideExample cop.([@thijsnado][])
 
 ## 1.43.2 (2020-08-25)
 
@@ -565,3 +566,4 @@ Compatibility release so users can upgrade RuboCop to 0.51.0. No new features.
 [@biinari]: https://github.com/biinari
 [@koic]: https://github.com/koic
 [@Rafix02]: https://github.com/Rafix02
+[@thijsnado]: https://github.com/thijsnado

config/default.yml

@@ -671,3 +671,25 @@ Rails/HttpStatus:
   - symbolic
   VersionAdded: '1.23'
   StyleGuide: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/Rails/HttpStatus
+
+Rails/PersistenceCalledOutsideExample:
+  Description: Checks for persistence calls outside example blocks.
+  Enabled: true
+  VersionAdded: '1.43'
+  AllowedMethods: []
+  ForbiddenMethods:
+  - create
+  - create!
+  - build
+  - create_list
+  - build_list
+  - save
+  - save!
+  - create_or_find_by
+  - create_or_find_by!
+  - find_or_create_by
+  - find_or_create_by!
+  - first_or_create
+  - first_or_create!
+  - Fabricate
+  StyleGuide: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/Rails/PersistenceCalledOutsideExample

docs/modules/ROOT/pages/cops.adoc

@@ -98,5 +98,6 @@
 === Department xref:cops_rails.adoc[Rails]
 
 * xref:cops_rails.adoc#railshttpstatus[Rails/HttpStatus]
+* xref:cops_rails.adoc#railspersistencecalledoutsideexample[Rails/PersistenceCalledOutsideExample]
 
 // END_COP_LIST

docs/modules/ROOT/pages/cops_rails.adoc

@@ -59,3 +59,64 @@ it { is_expected.to have_http_status :error }
 === References
 
 * https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/Rails/HttpStatus
+
+== Rails/PersistenceCalledOutsideExample
+
+|===
+| Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged
+
+| Enabled
+| Yes
+| No
+| 1.43
+| -
+|===
+
+Checks for persistence calls outside example blocks.
+
+Prevents persistence calls outside examples which usually run
+with some sort of cleanup hook. Saving outside of example causes
+records to leak into other tests.
+
+@ example
+  # bad - records created outside example group
+  describe User do
+    User.create!
+  end
+
+  describe User do
+    user = User.new
+    user.save!
+  end
+
+  # good - records created inside an example group
+  describe User do
+    it do
+      User.create!
+    end
+  end
+
+  describe User do
+    it do
+      user = User.new
+      user.save!
+    end
+  end
+
+=== Configurable attributes
+
+|===
+| Name | Default value | Configurable values
+
+| AllowedMethods
+| `[]`
+| Array
+
+| ForbiddenMethods
+| `create`, `create!`, `build`, `create_list`, `build_list`, `save`, `save!`, `create_or_find_by`, `create_or_find_by!`, `find_or_create_by`, `find_or_create_by!`, `first_or_create`, `first_or_create!`, `Fabricate`
+| Array
+|===
+
+=== References
+
+* https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/Rails/PersistenceCalledOutsideExample

lib/rubocop/cop/rspec/rails/persistence_called_outside_example.rb

@@ -0,0 +1,97 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module RSpec
+      module Rails
+        # Checks for persistence calls outside example blocks.
+        #
+        # Prevents persistence calls outside examples which usually run
+        # with some sort of cleanup hook. Saving outside of example causes
+        # records to leak into other tests.
+        #
+        # @ example
+        #   # bad - records created outside example group
+        #   describe User do
+        #     User.create!
+        #   end
+        #
+        #   describe User do
+        #     user = User.new
+        #     user.save!
+        #   end
+        #
+        #   # good - records created inside an example group
+        #   describe User do
+        #     it do
+        #       User.create!
+        #     end
+        #   end
+        #
+        #   describe User do
+        #     it do
+        #       user = User.new
+        #       user.save!
+        #     end
+        #   end
+        class PersistenceCalledOutsideExample < Base
+          MSG = 'Persistence called outside of example.'
+
+          def on_send(node)
+            return if inside_example_scope?(node) ||
+              inside_method_definition?(node) ||
+              inside_proc_or_lambda?(node) ||
+              allowed_method?(node)
+            return unless inside_describe_block?(node)
+            return unless persistent_call?(node)
+
+            add_offense(node)
+          end
+
+          private
+
+          def inside_example_scope?(node)
+            node.each_ancestor(:block).any?(&method(:example_scope?))
+          end
+
+          def example_scope?(node)
+            example?(node) ||
+              let?(node) ||
+              hook?(node) ||
+              subject?(node)
+          end
+
+          def inside_method_definition?(node)
+            node.each_ancestor(:def).any?
+          end
+
+          def inside_proc_or_lambda?(node)
+            node.each_ancestor(:block).any?(&:lambda_or_proc?)
+          end
+
+          def allowed_method?(node)
+            allowed_methods.include?(node.method_name.to_s)
+          end
+
+          def allowed_methods
+            cop_config['AllowedMethods'] || []
+          end
+
+          def inside_describe_block?(node)
+            node.each_ancestor(:block).any?(&method(:spec_group?))
+          end
+
+          def persistent_call?(node)
+            method_name = node.method_name.to_s
+
+            forbidden_methods.include?(method_name)
+          end
+
+          def forbidden_methods
+            cop_config['ForbiddenMethods'] || []
+          end
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/rspec_cops.rb

@@ -13,6 +13,7 @@
 rescue LoadError
   # Rails/HttpStatus cannot be loaded if rack/utils is unavailable.
 end
+require_relative 'rspec/rails/persistence_called_outside_example'
 
 require_relative 'rspec/align_left_let_brace'
 require_relative 'rspec/align_right_let_brace'