Add qemu-based multiarch build/test CI

.github/workflows/qemu.yml

@@ -0,0 +1,37 @@
+name: Cross-Architecture Test
+
+on: [push, pull_request]
+
+jobs:
+  test:
+    strategy:
+      matrix:
+        include:
+          - arch: amd64
+            qemu_arch: x86_64
+          - arch: arm64v8
+            qemu_arch: aarch64
+          - arch: i386
+            qemu_arch: i386
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+        with:
+          platforms: ${{ matrix.qemu_arch }}
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+
+      - name: Available platforms
+        run: echo ${{ steps.qemu.outputs.platforms }}
+
+      - name: Run cargo test
+        run: |
+          docker run --rm --privileged multiarch/qemu-user-static --reset -p yes
+          docker run --rm -v "$PWD":/usr/src/myapp -w /usr/src/myapp ${{ matrix.arch }}/rust cargo test