1 files changed, 40 insertions, 0 deletions
diff --git a/spec/lib/gitlab/usage/metrics/names_suggestions/relation_parsers/joins_spec.rb b/spec/lib/gitlab/usage/metrics/names_suggestions/relation_parsers/joins_spec.rb
new file mode 100644
index 00000000000..fb3bd564e34
--- /dev/null
+++ b/spec/lib/gitlab/usage/metrics/names_suggestions/relation_parsers/joins_spec.rb
@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Usage::Metrics::NamesSuggestions::RelationParsers::Joins do
+  describe '#accept' do
+    let(:collector) { Arel::Collectors::SubstituteBinds.new(ActiveRecord::Base.connection, Arel::Collectors::SQLString.new) }
+
+    context 'with join added via string' do
+      it 'collects join parts' do
+        arel = Issue.joins('LEFT JOIN projects ON projects.id = issue.project_id')
+
+        arel = arel.arel
+        result = described_class.new(ApplicationRecord.connection).accept(arel)
+
+        expect(result).to match_array [{ source: "projects", constraints: "projects.id = issue.project_id" }]
+      end
+    end
+
+    context 'with join added via arel node' do
+      it 'collects join parts' do
+        source_table = Arel::Table.new('records')
+        joined_table = Arel::Table.new('joins')
+        second_level_joined_table = Arel::Table.new('second_level_joins')
+
+        arel = source_table
+                 .from
+                 .project(source_table['id'].count)
+                 .join(joined_table, Arel::Nodes::OuterJoin)
+                 .on(source_table[:id].eq(joined_table[:records_id]))
+                 .join(second_level_joined_table, Arel::Nodes::OuterJoin)
+                 .on(joined_table[:id].eq(second_level_joined_table[:joins_id]))
+
+        result = described_class.new(ApplicationRecord.connection).accept(arel)
+
+        expect(result).to match_array [{ source: "joins", constraints: "records.id = joins.records_id" }, { source: "second_level_joins", constraints: "joins.id = second_level_joins.joins_id" }]
+      end
+    end
+  end
+end