chore: switch from Codecov to Coveralls

- Add coveralls_reborn and simplecov-lcov gems
- Update spec_helper.rb with Coveralls formatter
- Update CI workflow to use COVERALLS_REPO_TOKEN
- Update README badges to use Coveralls

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: yhk1038

.github/workflows/ci.yml

@@ -72,18 +72,10 @@ jobs:
           bundler-cache: true
 
       - name: Run tests with coverage
-        run: |
-          COVERAGE=true bundle exec rspec
+        run: bundle exec rspec
         env:
           COVERAGE: true
-
-      - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v4
-        with:
-          token: ${{ secrets.CODECOV_TOKEN }}
-          files: ./coverage/coverage.xml
-          fail_ci_if_error: false
-          verbose: true
+          COVERALLS_REPO_TOKEN: ${{ secrets.COVERALLS_REPO_TOKEN }}
 
   # VSCode 플러그인 빌드
   vscode:

Gemfile

@@ -10,5 +10,6 @@ group :development, :test do
   gem "rspec_junit_formatter", "~> 0.6.0"
   gem "rubocop", require: false
   gem "simplecov", "~> 0.22.0", require: false
-  gem "simplecov-cobertura", "~> 2.1.0", require: false
+  gem "simplecov-lcov", "~> 0.8.0", require: false
+  gem "coveralls_reborn", "~> 0.28.0", require: false
 end

README.ja.md

@@ -13,7 +13,7 @@
   <img src="https://img.shields.io/badge/ruby-3.0+-cc342d" alt="Ruby 3.0+" />
   <a href="https://rubygems.org/gems/t-ruby"><img src="https://img.shields.io/gem/v/t-ruby" alt="Gem Version" /></a>
   <img src="https://img.shields.io/gem/dt/t-ruby" alt="Downloads" />
-  <a href="https://codecov.io/gh/type-ruby/t-ruby"><img src="https://codecov.io/gh/type-ruby/t-ruby/branch/main/graph/badge.svg" alt="Coverage" /></a>
+  <a href="https://coveralls.io/github/type-ruby/t-ruby?branch=main"><img src="https://coveralls.io/repos/github/type-ruby/t-ruby/badge.svg?branch=main" alt="Coverage" /></a>
 </p>
 
 <p align="center">

README.ko.md

@@ -13,7 +13,7 @@
   <img src="https://img.shields.io/badge/ruby-3.0+-cc342d" alt="Ruby 3.0+" />
   <a href="https://rubygems.org/gems/t-ruby"><img src="https://img.shields.io/gem/v/t-ruby" alt="Gem Version" /></a>
   <img src="https://img.shields.io/gem/dt/t-ruby" alt="Downloads" />
-  <a href="https://codecov.io/gh/type-ruby/t-ruby"><img src="https://codecov.io/gh/type-ruby/t-ruby/branch/main/graph/badge.svg" alt="Coverage" /></a>
+  <a href="https://coveralls.io/github/type-ruby/t-ruby?branch=main"><img src="https://coveralls.io/repos/github/type-ruby/t-ruby/badge.svg?branch=main" alt="Coverage" /></a>
 </p>
 
 <p align="center">

README.md

@@ -13,7 +13,7 @@
   <img src="https://img.shields.io/badge/ruby-3.0+-cc342d" alt="Ruby 3.0+" />
   <a href="https://rubygems.org/gems/t-ruby"><img src="https://img.shields.io/gem/v/t-ruby" alt="Gem Version" /></a>
   <img src="https://img.shields.io/gem/dt/t-ruby" alt="Downloads" />
-  <a href="https://codecov.io/gh/type-ruby/t-ruby"><img src="https://codecov.io/gh/type-ruby/t-ruby/branch/main/graph/badge.svg" alt="Coverage" /></a>
+  <a href="https://coveralls.io/github/type-ruby/t-ruby?branch=main"><img src="https://coveralls.io/repos/github/type-ruby/t-ruby/badge.svg?branch=main" alt="Coverage" /></a>
 </p>
 
 <p align="center">

spec/spec_helper.rb

@@ -9,12 +9,22 @@
 
   formatters = [SimpleCov::Formatter::HTMLFormatter]
 
-  # Only add Cobertura formatter if it loads successfully
-  begin
-    require "simplecov-cobertura"
-    formatters << SimpleCov::Formatter::CoberturaFormatter
-  rescue LoadError
-    # simplecov-cobertura not available
+  # Add Coveralls formatter for CI
+  if ENV["CI"]
+    begin
+      require "simplecov-lcov"
+      require "coveralls_reborn"
+
+      SimpleCov::Formatter::LcovFormatter.config do |c|
+        c.report_with_single_file = true
+        c.single_report_path = "coverage/lcov.info"
+      end
+
+      formatters << SimpleCov::Formatter::LcovFormatter
+      formatters << Coveralls::SimpleCov::Formatter
+    rescue LoadError
+      # coveralls not available
+    end
   end
 
   SimpleCov.formatters = SimpleCov::Formatter::MultiFormatter.new(formatters)