Add a cop for `FinderMethods`bvl-finder-methods-cop

This notifies developers when calling `find(_by!)` chained on
`execute`. And suggests using the methods from `FinderMethods`. These
will perform the correct authorization checks on the resource when it
is found.

1 files changed, 56 insertions, 0 deletions

diff --git a/spec/rubocop/cop/gitlab/finder_with_find_by_spec.rb b/spec/rubocop/cop/gitlab/finder_with_find_by_spec.rb
new file mode 100644
index 00000000000..7f689b196c5
--- /dev/null
+++ b/spec/rubocop/cop/gitlab/finder_with_find_by_spec.rb
@@ -0,0 +1,56 @@
+require 'spec_helper'
+
+require 'rubocop'
+require 'rubocop/rspec/support'
+
+require_relative '../../../../rubocop/cop/gitlab/finder_with_find_by'
+
+describe RuboCop::Cop::Gitlab::FinderWithFindBy do
+  include CopHelper
+
+  subject(:cop) { described_class.new }
+
+  context 'when calling execute.find' do
+    let(:source) do
+      <<~SRC
+      DummyFinder.new(some_args)
+        .execute
+        .find_by!(1)
+      SRC
+    end
+    let(:corrected_source) do
+      <<~SRC
+      DummyFinder.new(some_args)
+        .find_by!(1)
+      SRC
+    end
+
+    it 'registers an offence' do
+      inspect_source(source)
+
+      expect(cop.offenses.size).to eq(1)
+    end
+
+    it 'can autocorrect the source' do
+      expect(autocorrect_source(source)).to eq(corrected_source)
+    end
+
+    context 'when called within the `FinderMethods` module' do
+      let(:source) do
+        <<~SRC
+          module FinderMethods
+            def find_by!(*args)
+              execute.find_by!(args)
+            end
+          end
+        SRC
+      end
+
+      it 'does not register an offence' do
+        inspect_source(source)
+
+        expect(cop.offenses).to be_empty
+      end
+    end
+  end
+end