Check formatting in CI

.github/workflows/rust.yml

@@ -63,6 +63,27 @@ jobs:
         if: matrix.os == 'macos-latest'
         run: sudo bash integration-tests/macos.sh
 
+  format:
+    name: Format
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v2
+        with:
+          persist-credentials: false
+      - name: Install rust toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          override: true
+          default: true
+          components: rustfmt
+      - name: Check formatting
+        uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: --all -- --check
+
   clippy:
     name: Clippy
     runs-on: ubuntu-latest

rustfmt.toml

@@ -0,0 +1 @@
+chain_width=40