1 files changed, 62 insertions, 0 deletions
diff --git a/spec/rubocop/cop/performance/ar_count_each_spec.rb b/spec/rubocop/cop/performance/ar_count_each_spec.rb
new file mode 100644
index 00000000000..f934a1fde48
--- /dev/null
+++ b/spec/rubocop/cop/performance/ar_count_each_spec.rb
@@ -0,0 +1,62 @@
+# frozen_string_literal: true
+
+require 'fast_spec_helper'
+require_relative '../../../support/helpers/expect_offense'
+require_relative '../../../../rubocop/cop/performance/ar_count_each.rb'
+
+describe RuboCop::Cop::Performance::ARCountEach do
+  include CopHelper
+  include ExpectOffense
+
+  subject(:cop) { described_class.new }
+
+  context 'when it is not haml file' do
+    it 'does not flag it as an offense' do
+      expect(subject).to receive(:in_haml_file?).with(anything).at_least(:once).and_return(false)
+
+      expect_no_offenses <<~SOURCE
+        show(@users.count)
+        @users.each { |user| display(user) }
+      SOURCE
+    end
+  end
+
+  context 'when it is haml file' do
+    before do
+      expect(subject).to receive(:in_haml_file?).with(anything).at_least(:once).and_return(true)
+    end
+
+    context 'when the same object uses count and each' do
+      it 'flags it as an offense' do
+        expect_offense <<~SOURCE
+        show(@users.count)
+             ^^^^^^^^^^^^ If @users is AR relation, avoid `@users.count ...; @users.each... `, this will trigger two queries. Use `@users.load.size ...; @users.each... ` instead. If @users is an array, try to use @users.size.
+        @users.each { |user| display(user) }
+        SOURCE
+
+        expect(cop.offenses.map(&:cop_name)).to contain_exactly('Performance/ARCountEach')
+      end
+    end
+
+    context 'when different object uses count and each' do
+      it 'does not flag it as an offense' do
+        expect_no_offenses <<~SOURCE
+        show(@emails.count)
+        @users.each { |user| display(user) }
+        SOURCE
+      end
+    end
+
+    context 'when just using count without each' do
+      it 'does not flag it as an offense' do
+        expect_no_offenses '@users.count'
+      end
+    end
+
+    context 'when just using each without count' do
+      it 'does not flag it as an offense' do
+        expect_no_offenses '@users.each { |user| display(user) }'
+      end
+    end
+  end
+end