Changing test workflow to matrix

.github/workflows/test-matrix.yml

@@ -0,0 +1,30 @@
+name: "Action Test (Ubuntu)"
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  # test action works running from the graph  
+  test:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest]
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v1
+    - name: Run Workflow
+      id: write_file
+      uses: ./
+      with:
+        fileName: 'myTemporaryFile.txt'
+        encodedString: ${{ secrets.SOME_ENCODED_STRING }} # SGVsbG8sIFdvcmxkIQ==
+    - name: Echo file
+      run: |
+        echo ${{ steps.write_file.outputs.filePath }}
+    - name: Upload Artifact
+      uses: actions/upload-artifact@master
+      with:
+        name: 'final-file-${{ matrix.os }}.txt'
+        path: ${{ steps.write_file.outputs.filePath }}