Try to support Nix flakes from HEAD

Author: IvanIsCoding

.github/workflows/test_prebuilt_binaries.yml

@@ -254,6 +254,20 @@ jobs:
 
       - name: Build Flake and show celq version
         run: nix run github:IvanIsCoding/celq -- --version
+  
+    test-nix-flake-latest:
+    name: Test Nix flake (latest) validity and run
+    runs-on: ubuntu-24.04
+    steps:
+      - name: Install Nix
+        uses: cachix/install-nix-action@v26
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
+          extra_nix_config: |
+            experimental-features = nix-command flakes
+
+      - name: Build Flake with latest version and show celq version
+        run: nix run github:IvanIsCoding/celq#latest -- --version
 
   test-freebsd-install:
     name: Test FreeBSD 14.3 (x86_64)

flake.nix

@@ -22,6 +22,8 @@
         {
           # Compiles from source with Cargo and installs celq. That part I understood!
           default = pkgs.callPackage ./nix/celq.nix { };
+          # Latest version from HEAD
+          latest = pkgs.callPackage ./nix/celq_latest.nix { };
         });
     };
 }

nix/celq_latest.nix

@@ -0,0 +1,55 @@
+{
+  lib,
+  rustPlatform,
+  fetchCrate,
+  versionCheckHook,
+  runCommand,
+}:
+
+let
+  cargoToml = builtins.fromTOML (builtins.readFile ../Cargo.toml);
+in
+
+rustPlatform.buildRustPackage (finalAttrs: {
+  pname = "celq";
+  version = cargoToml.package.version;
+
+  # Fetch from HEAD
+  src = lib.cleanSource ../.;
+
+  cargoLock = {
+    lockFile = ../Cargo.lock;
+    allowBuiltinFetchGit = true;
+  };
+
+  nativeInstallCheckInputs = [
+    versionCheckHook
+  ];
+
+  passthru = {
+    tests.simple =
+      runCommand "celq-test"
+        {
+          nativeBuildInputs = [ finalAttrs.finalPackage ];
+        }
+        ''
+          set -o pipefail
+
+          # Test the command `celq -n "1 > 0"`, which should return exit code 0
+          if ! celq -n "1 > 0"; then
+            echo "Test failed: celq can't execute simple expression"
+            exit 1
+          else
+            echo "Test passed: celq executed simple expression successfully"
+          fi
+        '';
+  };
+
+  meta = {
+    description = "celq - A Common Expression Language (CEL) CLI Tool";
+    homepage = "https://github.com/IvanIsCoding/celq";
+    license = lib.licenses.mit;
+    mainProgram = "celq";
+    platforms = lib.platforms.unix;
+  };
+})