Add Actions job to run macrotest

.github/workflows/ci.yml

@@ -60,6 +60,18 @@ jobs:
       - run: cd test_suite/no_std && cargo build
         if: matrix.os != 'windows'
 
+  macro:
+    name: Macro test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dtolnay/rust-toolchain@nightly
+      - name: Download cargo-expand
+        run: |
+          curl -sSo ~/.cargo/bin/cargo-expand https://github.com/dtolnay/cargo-expand/releases/download/0.6.0/cargo-expand
+          chmod +x ~/.cargo/bin/cargo-expand
+      - run: cd test_suite && cargo test --test expandtest
+
   msrv:
     name: Rust 1.13.0
     runs-on: ubuntu-latest