Add explanation of skipped tests

Author: johnnyshields

.github/workflows/test.yml

@@ -8,17 +8,27 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-20.04]
+        os: [ubuntu-20.04] # macos-latest
         ruby-version: [2.6, 2.7, 3.0, 3.1, 3.2, jruby-9.3, jruby-9.4, truffleruby]
         include:
           - os: macos-latest
             ruby-version: 2.6
+          - os: macos-latest
+            ruby-version: 2.7
           - os: macos-latest
             ruby-version: 3.0
+          - os: macos-latest
+            ruby-version: 3.1
           - os: macos-latest
             ruby-version: 3.2
           - os: macos-latest
             ruby-version: jruby-9.3
+          # 2023/03/07 - JRuby 9.4 on MacOS is skipped for now.
+          # Seems to be a JRuby-side issue.
+          # - os: macos-latest
+          #   ruby-version: jruby-9.4
+          - os: macos-latest
+            ruby-version: truffleruby
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v2
@@ -35,6 +45,8 @@ jobs:
 
       - name: Coveralls
         uses: coverallsapp/github-action@master
+        # 2023/03/07 - Simplecov is not working on TruffleRuby.
+        # TruffleRuby tests are otherwise passing.
         if: ${{ matrix.ruby-version != 'truffleruby' }}
         with:
           github-token: ${{ secrets.github_token }}

test/test_helper.rb

@@ -1,3 +1,4 @@
+# 2023/03/07 - Simplecov is not working on TruffleRuby.
 unless defined?(TruffleRuby)
   require 'simplecov'
   require 'simplecov-lcov'