Capture test output for Minitest reporter

lib/ruby_lsp/ruby_lsp_reporter_plugin.rb

@@ -11,6 +11,9 @@ class RubyLspReporter < ::Minitest::AbstractReporter
       class << self
         #: (Hash[untyped, untyped]) -> void
         def minitest_plugin_init(_options)
+          # We wrap the default output stream so that we can capture anything written to stdout and emit it as part of
+          # the JSON event stream.
+          $> = RubyLsp::TestReporter::IOWrapper.new($stdout)
           Minitest.reporter.reporters = [RubyLspReporter.new]
         end
       end

lib/ruby_lsp/test_reporter.rb

@@ -2,6 +2,7 @@
 # frozen_string_literal: true
 
 require "json"
+require "delegate"
 
 $stdout.binmode
 $stdout.sync = true
@@ -59,6 +60,14 @@ def record_error(id:, message:, uri:)
         send_message("error", params)
       end
 
+      #: (message: String) -> void
+      def write_stdout(message:)
+        params = {
+          message: message,
+        }
+        send_message("write_stdout", params)
+      end
+
       private
 
       #: (method_name: String?, params: Hash[String, untyped]) -> void
@@ -67,5 +76,24 @@ def send_message(method_name, params)
         $stdout.write("Content-Length: #{json_message.bytesize}\r\n\r\n#{json_message}")
       end
     end
+
+    class IOWrapper < SimpleDelegator
+      #: (Array[String]) -> void
+      def puts(*args)
+        args.each { |arg| log("#{arg}\n") }
+      end
+
+      #: (Array[String]) -> void
+      def print(*args)
+        args.each { |arg| log(arg.to_s) }
+      end
+
+      private
+
+      #: (String) -> void
+      def log(message)
+        TestReporter.write_stdout(message: message)
+      end
+    end
   end
 end

test/fixtures/minitest_example.rb

@@ -23,4 +23,8 @@ def test_that_is_pending
   def test_that_raises
     raise "oops"
   end
+
+  def test_with_output
+    $stdout.puts "hello from stdout"
+  end
 end

test/minitest_test_runner_test.rb

@@ -82,8 +82,28 @@ def test_minitest_output
             "uri" => uri,
           },
         },
+        {
+          "method" => "start",
+          "params" => {
+            "id" => "SampleTest#test_with_output",
+            "uri" => uri,
+          },
+        },
+        {
+          "method" => "write_stdout",
+          "params" => {
+            "message" => "hello from stdout\n",
+          },
+        },
+        {
+          "method" => "pass",
+          "params" => {
+            "id" => "SampleTest#test_with_output",
+            "uri" => uri,
+          },
+        },
       ]
-      assert_equal(8, actual.size)
+      assert_equal(2 + 2 + 2 + 2 + 3, actual.size)
       assert_equal(expected, actual)
     end