Show index operator classes in annotations

lib/annotate_rb/model_annotator/index_annotation/index_component.rb

@@ -136,13 +136,23 @@ def to_markdown
 
         def columns_info
           Array(index.columns).map do |col|
-            if index.try(:orders) && index.orders[col.to_s]
-              "#{col} #{index.orders[col.to_s].upcase}"
-            else
-              col.to_s.gsub("\r", '\r').gsub("\n", '\n')
-            end
+            column = col.to_s.gsub("\r", '\r').gsub("\n", '\n')
+            opclass = column_option(:opclasses, col)
+            order = column_option(:orders, col)
+
+            [column, opclass, order&.upcase].compact.join(" ")
           end
         end
+
+        # ActiveRecord condenses per column index options (`opclasses`, `orders`)
+        # into a single value when every column shares the same one, so the
+        # option can either be a Hash keyed by column or a bare value.
+        def column_option(option, col)
+          value = index.try(option)
+          value = value[col.to_s] if value.is_a?(Hash)
+
+          value.presence&.to_s
+        end
       end
     end
   end

spec/lib/annotate_rb/model_annotator/index_annotation/annotation_builder_spec.rb

@@ -67,6 +67,103 @@
       end
     end
 
+    context "index has the same order for every column" do
+      let(:indexes) do
+        [
+          mock_index("index_rails_02e851e3b8",
+            columns: %w[firstname surname],
+            orders: :desc)
+        ]
+      end
+
+      let(:expected_result) do
+        <<~EOS.strip
+          #
+          # Indexes
+          #
+          #  index_rails_02e851e3b8  (firstname DESC,surname DESC)
+        EOS
+      end
+
+      it "matches the expected result" do
+        expect(default_format).to eq(expected_result)
+      end
+    end
+
+    context "index includes an operator class" do
+      let(:indexes) do
+        [
+          mock_index("index_rails_02e851e3b7", columns: ["id"]),
+          mock_index("index_rails_02e851e3b8",
+            columns: %w[firstname surname],
+            opclasses: {"surname" => :text_pattern_ops}),
+          mock_index("index_rails_02e851e3b9",
+            columns: %w[firstname surname],
+            opclasses: {"firstname" => :text_pattern_ops, "surname" => :text_pattern_ops},
+            orders: {"surname" => :desc})
+        ]
+      end
+
+      let(:expected_default) do
+        <<~EOS.strip
+          #
+          # Indexes
+          #
+          #  index_rails_02e851e3b7  (id)
+          #  index_rails_02e851e3b8  (firstname,surname text_pattern_ops)
+          #  index_rails_02e851e3b9  (firstname text_pattern_ops,surname text_pattern_ops DESC)
+        EOS
+      end
+
+      let(:expected_markdown) do
+        <<~EOS.strip
+          #
+          # ### Indexes
+          #
+          # * `index_rails_02e851e3b7`:
+          #     * **`id`**
+          # * `index_rails_02e851e3b8`:
+          #     * **`firstname`**
+          #     * **`surname text_pattern_ops`**
+          # * `index_rails_02e851e3b9`:
+          #     * **`firstname text_pattern_ops`**
+          #     * **`surname text_pattern_ops DESC`**
+        EOS
+      end
+
+      it "includes the operator class in default format" do
+        expect(default_format).to eq(expected_default)
+      end
+
+      it "includes the operator class in markdown format" do
+        expect(markdown_format).to eq(expected_markdown)
+      end
+    end
+
+    context "index has the same operator class for every column" do
+      let(:indexes) do
+        [
+          mock_index("index_rails_02e851e3b8",
+            columns: %w[name],
+            opclasses: :gist_trgm_ops,
+            using: "gist")
+        ]
+      end
+
+      let(:expected_result) do
+        <<~EOS.strip
+          #
+          # Indexes
+          #
+          #  index_rails_02e851e3b8  (name gist_trgm_ops) USING gist
+        EOS
+      end
+
+      it "matches the expected result" do
+        expect(default_format).to eq(expected_result)
+      end
+    end
+
     context "index includes a where clause" do
       let(:indexes) do
         [

spec/support/annotate_test_helpers.rb

@@ -23,6 +23,7 @@ def mock_index(name, params = {})
       unique: params[:unique] || false,
       nulls_not_distinct: params[:nulls_not_distinct] || false,
       orders: params[:orders] || {},
+      opclasses: params[:opclasses] || {},
       where: params[:where],
       using: params[:using],
       comment: params[:comment])