Handle schema_dump_path being unavailable in older Rails versions

lib/ruby_lsp/ruby_lsp_rails/server.rb

@@ -26,7 +26,7 @@ class Server
 
       extend T::Sig
 
-      sig { params(model_name: String).returns(T.nilable(T::Hash[Symbol, T.untyped])) }
+      sig { params(model_name: String).returns(T::Hash[Symbol, T.untyped]) }
       def resolve_database_info_from_model(model_name)
         const = ActiveSupport::Inflector.safe_constantize(model_name)
         unless const && const < ActiveRecord::Base && !const.abstract_class?
@@ -35,14 +35,18 @@ def resolve_database_info_from_model(model_name)
           }
         end
 
-        schema_file = ActiveRecord::Tasks::DatabaseTasks.schema_dump_path(const.connection.pool.db_config)
-
-        {
+        info = {
           result: {
             columns: const.columns.map { |column| [column.name, column.type] },
-            schema_file: ::Rails.root + schema_file,
           },
         }
+
+        if ActiveRecord::Tasks::DatabaseTasks.respond_to?(:schema_dump_path)
+          info[:result][:schema_file] =
+            ActiveRecord::Tasks::DatabaseTasks.schema_dump_path(const.connection.pool.db_config)
+
+        end
+        info
       rescue => e
         {
           error: e.message,

test/ruby_lsp_rails/runner_client_test.rb

@@ -16,6 +16,8 @@ class RunnerClientTest < ActiveSupport::TestCase
         assert_predicate @client, :stopped?
       end
 
+      # These are integration tests which start the server. For the more fine-grained tests, see `server_test.rb`.
+
       test "#model returns information for the requested model" do
         # These columns are from the schema in the dummy app: test/dummy/db/schema.rb
         columns = [
@@ -31,16 +33,8 @@ class RunnerClientTest < ActiveSupport::TestCase
         assert_match(%r{db/schema\.rb$}, response.fetch(:schema_file))
       end
 
-      test "returns nil if model doesn't exist" do
-        assert_nil @client.model("Foo")
-      end
-
-      test "returns nil if class is not a model" do
-        assert_nil @client.model("Time")
-      end
-
-      test "returns nil if class is an abstract model" do
-        assert_nil @client.model("ApplicationRecord")
+      test "returns nil if the request returns a nil response" do
+        assert_nil @client.model("ApplicationRecord") # ApplicationRecord is abstract
       end
     end
   end

test/ruby_lsp_rails/server_test.rb

@@ -0,0 +1,35 @@
+# typed: true
+# frozen_string_literal: true
+
+require "test_helper"
+require "ruby_lsp/ruby_lsp_rails/server"
+
+class ServerTest < ActiveSupport::TestCase
+  setup do
+    @server = RubyLsp::Rails::Server.new
+  end
+
+  test "returns nil if model doesn't exist" do
+    response = @server.resolve_database_info_from_model("Foo")
+    assert_nil(response.fetch(:result))
+  end
+
+  test "returns nil if class is not a model" do
+    response = @server.resolve_database_info_from_model("Time")
+    assert_nil(response.fetch(:result))
+  end
+
+  test "returns nil if class is an abstract model" do
+    response = @server.resolve_database_info_from_model("ApplicationRecord")
+    assert_nil(response.fetch(:result))
+  end
+
+  test "handles older Rails version which don't have `schema_dump_path`" do
+    ActiveRecord::Tasks::DatabaseTasks.send(:alias_method, :old_schema_dump_path, :schema_dump_path)
+    ActiveRecord::Tasks::DatabaseTasks.undef_method(:schema_dump_path)
+    response = @server.resolve_database_info_from_model("User")
+    assert_nil(response.fetch(:result)[:schema_file])
+  ensure
+    ActiveRecord::Tasks::DatabaseTasks.send(:alias_method, :schema_dump_path, :old_schema_dump_path)
+  end
+end