Ensure output printed during boot doesn't break LSP when starting (#310)

Co-authored-by: Andy Waite <[email protected]>

Author: andyw8

lib/ruby_lsp/ruby_lsp_rails/runner_client.rb

@@ -30,6 +30,9 @@ def create_client
 
       class InitializationError < StandardError; end
       class IncompleteMessageError < StandardError; end
+      class EmptyMessageError < StandardError; end
+
+      MAX_RETRIES = 5
 
       extend T::Sig
 
@@ -59,7 +62,16 @@ def initialize
         @stdout.binmode # for Windows compatibility
 
         $stderr.puts("Ruby LSP Rails booting server")
-        read_response
+        count = 0
+
+        begin
+          count += 1
+          read_response
+        rescue EmptyMessageError
+          $stderr.puts("Ruby LSP Rails is retrying initialize (#{count})")
+          retry if count < MAX_RETRIES
+        end
+
         $stderr.puts("Finished booting Ruby LSP Rails server")
 
         unless ENV["RAILS_ENV"] == "test"
@@ -134,7 +146,10 @@ def read_response
         headers = @stdout.gets("\r\n\r\n")
         raise IncompleteMessageError unless headers
 
-        raw_response = @stdout.read(headers[/Content-Length: (\d+)/i, 1].to_i)
+        content_length = headers[/Content-Length: (\d+)/i, 1].to_i
+        raise EmptyMessageError if content_length.zero?
+
+        raw_response = @stdout.read(content_length)
         response = JSON.parse(T.must(raw_response), symbolize_names: true)
 
         if response[:error]

test/ruby_lsp_rails/runner_client_test.rb

@@ -74,6 +74,22 @@ class RunnerClientTest < ActiveSupport::TestCase
       ensure
         FileUtils.mv("bin/rails_backup", "bin/rails")
       end
+
+      test "is resilient to extra output being printed during boot" do
+        content = File.read("test/dummy/config/application.rb")
+        FileUtils.mv("test/dummy/config/application.rb", "test/dummy/config/application.rb.bak")
+        junk = %{\nputs "1\r\n\r\nhello"}
+        File.write("test/dummy/config/application.rb", content + junk)
+
+        capture_subprocess_io do
+          client = RunnerClient.create_client
+
+          response = T.must(client.model("User"))
+          assert(response.key?(:columns))
+        end
+      ensure
+        FileUtils.mv("test/dummy/config/application.rb.bak", "test/dummy/config/application.rb")
+      end
     end
   end
 end