Add support for PostgreSQL operator classes to add_index

Add support for specifying non-default operator classes in PostgreSQL
indexes. An example CREATE INDEX query that becomes possible is:

    CREATE INDEX users_name ON users USING gist (name gist_trgm_ops);

Previously it was possible to specify the `gist` index but not the
custom operator class. The `add_index` call for the above query is:

    add_index :users, :name, using: :gist, opclasses: {name: :gist_trgm_ops}

3 files changed, 40 insertions, 5 deletions

diff --git a/activerecord/test/cases/adapters/postgresql/active_schema_test.rb b/activerecord/test/cases/adapters/postgresql/active_schema_test.rb
index 9929237546..99c53dadeb 100644
--- a/activerecord/test/cases/adapters/postgresql/active_schema_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/active_schema_test.rb
@@ -59,6 +59,9 @@ class PostgresqlActiveSchemaTest < ActiveRecord::PostgreSQLTestCase
       assert_equal expected, add_index(:people, "lower(last_name)", using: type, unique: true)
     end
 
+    expected = %(CREATE  INDEX  "index_people_on_last_name" ON "people" USING gist ("last_name" bpchar_pattern_ops))
+    assert_equal expected, add_index(:people, :last_name, using: :gist, opclass: { last_name: :bpchar_pattern_ops })
+
     assert_raise ArgumentError do
       add_index(:people, :last_name, algorithm: :copy)
     end
diff --git a/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb b/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
index f199519d86..1951230c8a 100644
--- a/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
@@ -248,12 +248,12 @@ module ActiveRecord
 
       def test_index_with_opclass
         with_example_table do
-          @connection.add_index "ex", "data varchar_pattern_ops"
-          index = @connection.indexes("ex").find { |idx| idx.name == "index_ex_on_data_varchar_pattern_ops" }
-          assert_equal "data varchar_pattern_ops", index.columns
+          @connection.add_index "ex", "data", opclass: "varchar_pattern_ops"
+          index = @connection.indexes("ex").find { |idx| idx.name == "index_ex_on_data" }
+          assert_equal ["data"], index.columns
 
-          @connection.remove_index "ex", "data varchar_pattern_ops"
-          assert_not @connection.indexes("ex").find { |idx| idx.name == "index_ex_on_data_varchar_pattern_ops" }
+          @connection.remove_index "ex", "data"
+          assert_not @connection.indexes("ex").find { |idx| idx.name == "index_ex_on_data" }
         end
       end
 
diff --git a/activerecord/test/cases/adapters/postgresql/schema_test.rb b/activerecord/test/cases/adapters/postgresql/schema_test.rb
index 5a64da028b..a6ae18a826 100644
--- a/activerecord/test/cases/adapters/postgresql/schema_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/schema_test.rb
@@ -500,6 +500,38 @@ class SchemaForeignKeyTest < ActiveRecord::PostgreSQLTestCase
   end
 end
 
+class SchemaIndexOpclassTest < ActiveRecord::PostgreSQLTestCase
+  include SchemaDumpingHelper
+
+  setup do
+    @connection = ActiveRecord::Base.connection
+    @connection.create_table "trains" do |t|
+      t.string :name
+      t.text :description
+    end
+  end
+
+  teardown do
+    @connection.drop_table "trains", if_exists: true
+  end
+
+  def test_string_opclass_is_dumped
+    @connection.execute "CREATE INDEX trains_name_and_description ON trains USING btree(name text_pattern_ops, description text_pattern_ops)"
+
+    output = dump_table_schema "trains"
+
+    assert_match(/opclass: "text_pattern_ops"/, output)
+  end
+
+  def test_non_default_opclass_is_dumped
+    @connection.execute "CREATE INDEX trains_name_and_description ON trains USING btree(name, description text_pattern_ops)"
+
+    output = dump_table_schema "trains"
+
+    assert_match(/opclass: \{"description"=>"text_pattern_ops"\}/, output)
+  end
+end
+
 class DefaultsUsingMultipleSchemasAndDomainTest < ActiveRecord::PostgreSQLTestCase
   setup do
     @connection = ActiveRecord::Base.connection