add CI

.github/workflows/ci.yaml

@@ -0,0 +1,32 @@
+name: CI
+
+on:
+  push: {}
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v1
+
+    - name: Mount bazel cache
+      uses: actions/cache@v1
+      with:
+        path: "/home/runner/.cache/bazel"
+        key: bazel
+
+    - name: Install bazelisk
+      run: |
+        curl -LO "https://github.com/bazelbuild/bazelisk/releases/download/v1.18.0/bazelisk-linux-amd64"
+        mkdir -p "${GITHUB_WORKSPACE}/bin/"
+        mv bazelisk-linux-amd64 "${GITHUB_WORKSPACE}/bin/bazel"
+        chmod +x "${GITHUB_WORKSPACE}/bin/bazel"
+
+    - name: Test
+      run: |
+        "${GITHUB_WORKSPACE}/bin/bazel" test //...
+
+    - name: Build
+      run: |
+        "${GITHUB_WORKSPACE}/bin/bazel" build //...