Add a github actions config file

.github/workflows/ci.yml

@@ -0,0 +1,47 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - "**"
+
+env:
+  CARGO_TERM_COLOR: always
+  CARGO_INCREMENTAL: 0
+
+jobs:
+  tests:
+    name: Tests
+    runs-on: macos-latest
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v2
+
+      # Work around https://github.com/actions/cache/issues/403.
+      - name: Use GNU tar
+        run: |
+          echo PATH="/usr/local/opt/gnu-tar/libexec/gnubin:$PATH" >> $GITHUB_ENV
+
+      - name: Cache artifacts
+        id: cache
+        uses: actions/cache@v2
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-cargo-${{ hashFiles('Cargo.lock') }}
+
+      - name: Install rust
+        if: steps.cache.outputs.cache-hit != 'true'
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          profile: minimal
+
+      - name: Run tests
+        run: cargo test
+