Add code formatting with purty (#171)

* Add code formatting with purty

* Purtify code

.github/workflows/test.yaml

@@ -21,4 +21,4 @@ jobs:
         run: nix-shell --run 'make build'
 
       - name: Test
-        run: nix-shell --run 'make test'
+        run: nix-shell --run 'make test-code'

.github/workflows/validate-formatting.yaml

@@ -0,0 +1,24 @@
+name: Validate Formatting
+
+on:
+  pull_request:
+  push:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+
+      - name: Check out codebase
+        uses: actions/checkout@v2
+
+      - name: Install nix
+        uses: cachix/install-nix-action@v12
+        with:
+          nix_path: nixpkgs=channel:nixos-20.09
+
+      - name: Build
+        run: nix-shell --run 'make build'
+
+      - name: Test
+        run: nix-shell --run 'make test-format'