Avoid need for special VOID return

lib/ruby_lsp/ruby_lsp_rails/server.rb

@@ -9,12 +9,10 @@
 module RubyLsp
   module Rails
     class Server
-      VOID = Object.new
-
-      def initialize
+      def initialize(stdout: $stdout, override_default_output_device: true)
         # Grab references to the original pipes so that we can change the default output device further down
         @stdin = $stdin
-        @stdout = $stdout
+        @stdout = stdout
         @stderr = $stderr
         @stdin.sync = true
         @stdout.sync = true
@@ -26,7 +24,7 @@ def initialize
         # # Set the default output device to be $stderr. This means that using `puts` by itself will default to printing
         # # to $stderr and only explicit `$stdout.puts` will go to $stdout. This reduces the chance that output coming
         # # from the Rails app will be accidentally sent to the client
-        $> = $stderr
+        $> = $stderr if override_default_output_device
 
         @running = true
       end
@@ -44,39 +42,36 @@ def start
           json = @stdin.read(headers[/Content-Length: (\d+)/i, 1].to_i)
 
           request = JSON.parse(json, symbolize_names: true)
-          response = execute(request.fetch(:method), request[:params])
-          next if response == VOID
-
-          json_response = response.to_json
-          @stdout.write("Content-Length: #{json_response.length}\r\n\r\n#{json_response}")
+          execute(request.fetch(:method), request[:params])
         end
       end
 
       def execute(request, params)
         case request
         when "shutdown"
           @running = false
-          VOID
         when "model"
-          resolve_database_info_from_model(params.fetch(:name))
+          write_response(resolve_database_info_from_model(params.fetch(:name)))
         when "association_target_location"
-          resolve_association_target(params)
+          write_response(resolve_association_target(params))
         when "reload"
           ::Rails.application.reloader.reload!
-          VOID
         when "route_location"
-          route_location(params.fetch(:name))
+          write_response(route_location(params.fetch(:name)))
         when "route_info"
-          resolve_route_info(params)
-        else
-          VOID
+          write_response(resolve_route_info(params))
         end
       rescue => e
-        { error: e.full_message(highlight: false) }
+        write_response({ error: e.full_message(highlight: false) })
       end
 
       private
 
+      def write_response(response)
+        json_response = response.to_json
+        @stdout.write("Content-Length: #{json_response.length}\r\n\r\n#{json_response}")
+      end
+
       def resolve_route_info(requirements)
         if requirements[:controller]
           requirements[:controller] = requirements.fetch(:controller).underscore.delete_suffix("_controller")

test/ruby_lsp_rails/server_test.rb

@@ -6,26 +6,27 @@
 
 class ServerTest < ActiveSupport::TestCase
   setup do
-    @server = RubyLsp::Rails::Server.new
+    @stdout = StringIO.new
+    @server = RubyLsp::Rails::Server.new(stdout: @stdout, override_default_output_device: false)
   end
 
   test "returns nil if model doesn't exist" do
-    response = @server.execute("model", { name: "Foo" })
+    @server.execute("model", { name: "Foo" })
     assert_nil(response.fetch(:result))
   end
 
   test "returns nil if class is not a model" do
-    response = @server.execute("model", { name: "Time" })
+    @server.execute("model", { name: "Time" })
     assert_nil(response.fetch(:result))
   end
 
   test "returns nil if class is an abstract model" do
-    response = @server.execute("model", { name: "ApplicationRecord" })
+    @server.execute("model", { name: "ApplicationRecord" })
     assert_nil(response.fetch(:result))
   end
 
   test "returns nil if constant is not a class" do
-    response = @server.execute("model", { name: "RUBY_VERSION" })
+    @server.execute("model", { name: "RUBY_VERSION" })
     assert_nil(response.fetch(:result))
   end
 
@@ -38,21 +39,21 @@ def <(other)
       end
     end
 
-    response = @server.execute("model", { name: "TestClassWithOverwrittenLessThan" })
+    @server.execute("model", { name: "TestClassWithOverwrittenLessThan" })
     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.execute("model", { name: "User" })
+    @server.execute("model", { name: "User" })
     assert_nil(response.fetch(:result)[:schema_file])
   ensure
     ActiveRecord::Tasks::DatabaseTasks.send(:alias_method, :schema_dump_path, :old_schema_dump_path)
   end
 
   test "resolve association returns the location of the target class of a has_many association" do
-    response = @server.execute(
+    @server.execute(
       "association_target_location",
       { model_name: "Organization", association_name: :memberships },
     )
@@ -61,7 +62,7 @@ def <(other)
   end
 
   test "resolve association returns the location of the target class of a belongs_to association" do
-    response = @server.execute(
+    @server.execute(
       "association_target_location",
       { model_name: "Membership", association_name: :organization },
     )
@@ -70,7 +71,7 @@ def <(other)
   end
 
   test "resolve association returns the location of the target class of a has_one association" do
-    response = @server.execute(
+    @server.execute(
       "association_target_location",
       { model_name: "User", association_name: :profile },
     )
@@ -79,7 +80,7 @@ def <(other)
   end
 
   test "resolve association returns the location of the target class of a has_and_belongs_to_many association" do
-    response = @server.execute(
+    @server.execute(
       "association_target_location",
       { model_name: "Profile", association_name: :labels },
     )
@@ -88,23 +89,23 @@ def <(other)
   end
 
   test "resolve association handles invalid model name" do
-    response = @server.execute(
+    @server.execute(
       "association_target_location",
       { model_name: "NotHere", association_name: :labels },
     )
     assert_nil(response.fetch(:result))
   end
 
   test "resolve association handles invalid association name" do
-    response = @server.execute(
+    @server.execute(
       "association_target_location",
       { model_name: "Membership", association_name: :labels },
     )
     assert_nil(response.fetch(:result))
   end
 
   test "resolve association handles class_name option" do
-    response = @server.execute(
+    @server.execute(
       "association_target_location",
       { model_name: "User", association_name: :location },
     )
@@ -113,18 +114,18 @@ def <(other)
   end
 
   test "route location returns the location for a valid route" do
-    response = @server.execute("route_location", { name: "user_path" })
+    @server.execute("route_location", { name: "user_path" })
     location = response[:result][:location]
     assert_match %r{test/dummy/config/routes.rb:4$}, location
   end
 
   test "route location returns nil for invalid routes" do
-    response = @server.execute("route_location", { name: "invalid_path" })
+    @server.execute("route_location", { name: "invalid_path" })
     assert_nil response[:result]
   end
 
   test "route info" do
-    response = @server.execute("route_info", { controller: "UsersController", action: "index" })
+    @server.execute("route_info", { controller: "UsersController", action: "index" })
 
     result = response[:result]
 
@@ -136,7 +137,8 @@ def <(other)
   end
 
   test "prints in the Rails application or server are automatically redirected to stderr" do
-    server = RubyLsp::Rails::Server.new
+    stdout = StringIO.new
+    server = RubyLsp::Rails::Server.new(stdout: stdout)
 
     server.instance_eval do
       def resolve_route_info(requirements)
@@ -145,11 +147,18 @@ def resolve_route_info(requirements)
       end
     end
 
-    stdout, stderr = capture_subprocess_io do
+    _, stderr = capture_subprocess_io do
       server.execute("route_info", { controller: "UsersController", action: "index" })
     end
 
-    assert_empty(stdout)
+    refute_match("Hello", stdout.string)
     assert_equal("Hello\n", stderr)
   end
+
+  private
+
+  def response
+    _headers, content = @stdout.string.split("\r\n\r\n")
+    JSON.parse(content, symbolize_names: true)
+  end
 end