Update GH Actions for multi-os

.github/workflows/test.yml

@@ -4,23 +4,37 @@ on: [push]
 
 jobs:
   build:
-
-    runs-on: ubuntu-latest
+    name: Test Node.js ${{ matrix.node-version }} on ${{ matrix.os }}
 
     strategy:
       matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
         node-version: [6.x, 8.x, 10.x, 12.x]
 
+    runs-on: ${{ matrix.os }}
+
     steps:
     - uses: actions/checkout@v1
+
     - name: Use Node.js ${{ matrix.node-version }}
       uses: actions/setup-node@v1
       with:
         node-version: ${{ matrix.node-version }}
-    - name: npm install, build, and test
-      run: |
-        npm install
-        npm run build --if-present
-        npm test
+
+    - name: Print Node.js Version
+      run: node --version
+
+    - name: Install Dependencies
+      run: npm install
+      env:
+        CI: true
+
+    - name: Run "build" step
+      run: npm run build --if-present
+      env:
+        CI: true
+
+    - name: Run tests
+      run: npm test
       env:
         CI: true