Replace OpenStruct in Ansi2json converter

lib/gitlab/ci/ansi2json/converter.rb

@@ -37,16 +37,13 @@ module Gitlab
 
           flush_current_line
 
-          # TODO: replace OpenStruct with a better type
-          # https://gitlab.com/gitlab-org/gitlab/issues/34305
-          OpenStruct.new(
+          Gitlab::Ci::Ansi2json::Result.new(
             lines: @lines,
             state: @state.encode,
             append: append,
             truncated: truncated,
             offset: start_offset,
-            size: stream.tell - start_offset,
-            total: stream.size
+            stream: stream
           )
         end
 

lib/gitlab/ci/ansi2json/result.rb

+# frozen_string_literal: true
+
+# Convertion result object class
+module Gitlab
+  module Ci
+    module Ansi2json
+      class Result
+        attr_reader :lines, :state, :append, :truncated, :offset, :size, :total
+
+        def initialize(lines:, state:, append:, truncated:, offset:, stream:)
+          @lines = lines
+          @state = state
+          @append = append
+          @truncated = truncated
+          @offset = offset
+          @size = stream.tell - offset
+          @total = stream.size
+        end
+      end
+    end
+  end
+end

spec/lib/gitlab/ci/ansi2json/result_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Gitlab::Ci::Ansi2json::Result do
+  let(:stream) { StringIO.new('hello') }
+  let(:state) { Gitlab::Ci::Ansi2json::State.new(nil, stream.size) }
+  let(:offset) { 0 }
+  let(:params) do
+    { lines: [], state: state, append: false, truncated: false, offset: offset, stream: stream }
+  end
+
+  subject { described_class.new(params) }
+
+  describe '#size' do
+    before do
+      stream.seek(5) # move stream cursor to the end
+    end
+
+    context 'when offset is at the start' do
+      let(:offset) { 0 }
+
+      it 'returns the full size' do
+        expect(subject.size).to eq(5)
+      end
+    end
+
+    context 'when offset is not zero' do
+      let(:offset) { 2 }
+
+      it 'returns the remaining size' do
+        expect(subject.size).to eq(3)
+      end
+    end
+  end
+
+  describe '#total' do
+    it 'returns size of stread' do
+      expect(subject.total).to eq(5)
+    end
+  end
+end