Added RuboCop cops to enforce code reuse rules

These Cops enforces the code reuse rules as defined in merge request
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/21254.

1 files changed, 77 insertions, 0 deletions

diff --git a/spec/rubocop/cop/code_reuse/finder_spec.rb b/spec/rubocop/cop/code_reuse/finder_spec.rb
new file mode 100644
index 00000000000..b04e053a4c3
--- /dev/null
+++ b/spec/rubocop/cop/code_reuse/finder_spec.rb
@@ -0,0 +1,77 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+require 'rubocop'
+require 'rubocop/rspec/support'
+require_relative '../../../../rubocop/cop/code_reuse/finder'
+
+describe RuboCop::Cop::CodeReuse::Finder do
+  include CopHelper
+
+  subject(:cop) { described_class.new }
+
+  it 'flags the use of a Finder inside another Finder' do
+    allow(cop)
+      .to receive(:in_finder?)
+      .and_return(true)
+
+    expect_offense(<<~SOURCE)
+      class FooFinder
+        def execute
+          BarFinder.new.execute
+          ^^^^^^^^^^^^^ Finders can not be used inside a Finder.
+        end
+      end
+    SOURCE
+
+    expect(cop.offenses.size).to eq(1)
+  end
+
+  it 'flags the use of a Finder inside a model class method' do
+    allow(cop)
+      .to receive(:in_model?)
+      .and_return(true)
+
+    expect_offense(<<~SOURCE)
+      class User
+        class << self
+          def second_method
+            BarFinder.new
+            ^^^^^^^^^^^^^ Finders can not be used inside model class methods.
+          end
+        end
+
+        def self.second_method
+          FooFinder.new
+          ^^^^^^^^^^^^^ Finders can not be used inside model class methods.
+        end
+      end
+    SOURCE
+  end
+
+  it 'does not flag the use of a Finder in a non Finder file' do
+    expect_no_offenses(<<~SOURCE)
+      class FooFinder
+        def execute
+          BarFinder.new.execute
+        end
+      end
+    SOURCE
+  end
+
+  it 'does not flag the use of a Finder in a regular class method' do
+    expect_no_offenses(<<~SOURCE)
+      class User
+        class << self
+          def second_method
+            BarFinder.new
+          end
+        end
+
+        def self.second_method
+          FooFinder.new
+        end
+      end
+    SOURCE
+  end
+end