Merge coverage results

parser and prism will differ in what they do,
so merge them together.

jruby doesn't seem to support coverage (maybe jruby bug?):
> KeyError: key not found: :branch

Author: Earlopain

.github/workflows/main.yml

@@ -47,20 +47,33 @@ jobs:
         with:
           ruby-version: "${{ matrix.ruby }}"
           bundler-cache: true
-      - run: NO_COVERAGE=true bundle exec rake spec
+      - run: bundle exec rake spec
         env:
           PARSER_ENGINE: ${{ matrix.parser_engine }}
+      - name: Upload Coverage Artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: coverage-ubuntu-${{ matrix.ruby }}-${{ matrix.parser_engine }}
+          path: coverage/.resultset.json
+          include-hidden-files: true
 
   coverage:
+    name: Check Coverage
+    needs: main
     runs-on: ubuntu-latest
-    name: "Test coverage"
+
     steps:
       - uses: actions/checkout@v4
+      - uses: actions/download-artifact@v4
+        name: Download Coverage Artifacts
+        with:
+          pattern: coverage-*
       - uses: ruby/setup-ruby@v1
         with:
-          ruby-version: "3.4"
+          ruby-version: ruby # Latest stable CRuby version
           bundler-cache: true
-      - run: bundle exec rake spec
+
+      - run: bundle exec rake coverage:ci
 
   edge-rubocop:
     runs-on: ubuntu-latest

spec/spec_helper.rb

@@ -3,7 +3,7 @@
 require 'rubocop'
 require 'rubocop/rspec/support'
 
-require 'simplecov' unless ENV['NO_COVERAGE']
+require 'simplecov' unless ENV['NO_COVERAGE'] || RUBY_ENGINE == 'jruby'
 
 module SpecHelper
   ROOT = Pathname.new(__dir__).parent.freeze

tasks/coverage.rake

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+namespace :coverage do
+  desc 'Report Coverage from merged CI runs'
+  task :ci do
+    require 'simplecov'
+
+    SimpleCov.collate Dir['coverage-*/.resultset.json']
+  end
+end