run action with specified generator job on multiple platforms

.github/workflows/test.yml

@@ -74,7 +74,10 @@ jobs:
         run: build/${{ matrix.lang == 'C' && 'hello_world_c' || 'hello_world' }}
 
   use-action-with-specified-generator:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [windows-latest, ubuntu-latest, macos-latest]
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3.3.0

action.yml

@@ -51,7 +51,12 @@ runs:
     - name: Install Ninja
       if: ${{ inputs.generator == 'Ninja' }}
       shell: bash
-      run: sudo apt install -y ninja-build
+      run: |
+        case "$OSTYPE" in
+          darwin*)  brew install ninja ;;
+          linux*)   sudo apt install -y ninja-build ;;
+          *)        choco install ninja ;;
+        esac
 
     - name: Configure CMake
       shell: bash