diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml
deleted file mode 100644
index e2d6452..0000000
--- a/.github/workflows/macos.yml
+++ /dev/null
@@ -1,13 +0,0 @@
-name: macos
-
-on: [push, pull_request]
-
-jobs:
-  build:
-    runs-on: macos-latest
-    steps:
-    - uses: actions/checkout@v2
-    - name: Install dependencies
-      run: bundle install
-    - name: Run test
-      run: rake
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 0000000..381a35e
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,29 @@
+name: Test
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        ruby: [ 'head', '3.0', '2.7', '2.6', '2.5' ]
+        os: [ 'ubuntu-latest', 'windows-latest' ]
+        include:
+          - { os: macos-latest, ruby: '2.6' }
+          - { os: ubuntu-latest, ruby: 'jruby-head' }
+          - { os: ubuntu-latest, ruby: 'jruby-9.2' }
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Ruby ${{ matrix.ruby }}
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true # 'bundle install' and cache
+      - name: Ensure new-enough RubyGems
+        run: gem update --system
+        if: ${{ matrix.ruby == '2.6' || matrix.ruby == '2.5' }}
+      - name: Run test
+        run: bundle exec rake
+        env:
+          JRUBY_OPTS: -X+O
diff --git a/.github/workflows/ubuntu.yml b/.github/workflows/ubuntu.yml
deleted file mode 100644
index 85139c7..0000000
--- a/.github/workflows/ubuntu.yml
+++ /dev/null
@@ -1,22 +0,0 @@
-name: ubuntu
-
-on: [push, pull_request]
-
-jobs:
-  build:
-    runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        ruby: [ 'head', '3.0', '2.7', '2.6', '2.5', 'jruby-head', 'jruby-9.2' ]
-    steps:
-    - uses: actions/checkout@v2
-    - name: Set up Ruby
-      uses: ruby/setup-ruby@v1
-      with:
-        ruby-version: ${{ matrix.ruby }}
-    - name: Install dependencies
-      run: bundle install
-    - name: Run test
-      run: rake
-      env:
-        JRUBY_OPTS: -X+O
diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml
deleted file mode 100644
index e20388d..0000000
--- a/.github/workflows/windows.yml
+++ /dev/null
@@ -1,21 +0,0 @@
-name: windows
-
-on: [push, pull_request]
-
-jobs:
-  build:
-    runs-on: windows-latest
-    strategy:
-      matrix:
-        ruby: [ 'head', '3.0', '2.7', '2.6', '2.5' ]
-    steps:
-    - uses: actions/checkout@v2
-    - name: Set up Ruby
-      uses: ruby/setup-ruby@v1
-      with:
-        ruby-version: ${{ matrix.ruby }}
-    - name: Install dependencies
-      run: bundle install
-    - name: Run test
-      run: rake
-      continue-on-error: true # test_fileutils.rb:424 and test_fileutils.rb:455