Add formatting & minimal dependency version check to CI.

Author: wsx-antithesis

.github/workflows/ci.yml

@@ -8,10 +8,15 @@ on:
     - main
 jobs:
   build:
+    strategy:
+      matrix:
+        min-version: [true, false]
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v3
     - uses: cachix/install-nix-action@v22
       with:
         nix_path: nixpkgs=channel:nixos-unstable
+    - if: ${{ matrix.min-version }}
+      run: nix develop . -c cargo update -Z direct-minimal-versions
     - run: nix flake check --keep-going --print-build-logs

flake.nix

@@ -65,15 +65,20 @@
     };
 
     devShells.default = pkgs: {
+      inputsFrom = with pkgs; [ antithesis-sdk-rust.workspace ];
       packages = with pkgs; [ rust-analyzer cargo-msrv ];
     };
 
-    # TODO: Check minimal versions of dependency, and feature flags.
-    # TODO: Do we what formatters?
+    # TODO: Check combinations of feature flags & semver check.
     checks = { antithesis-sdk-rust, ... }: {
       inherit (antithesis-sdk-rust) workspaceMSRV clippy test;
     };
 
+    formatters = pkgs: {
+      "*.rs" = "${pkgs.rustfmt}/bin/rustfmt";
+      "*.nix" = "${pkgs.nixpkgs-fmt}/bin/nixpkgs-fmt";
+    };
+
     flakelight.builtinFormatters = false;
   };
 }