feat(flake)!: nix provided via NIX_CMD_PATH

Co-authored-by: ruben beck <[email protected]>

.github/workflows/check.yaml

@@ -11,56 +11,28 @@ jobs:
     runs-on: ${{ matrix.runner }}
     steps:
       - uses: actions/checkout@v4
-      - name: cache
-        uses: FrancisRussell/[email protected]
-        with:
-          command: cache
-      - name: toolchain
-        uses: FrancisRussell/[email protected]
-        with:
-          command: install-rustup
-          toolchain: stable
-      - name: install Nix
-        uses: cachix/install-nix-action@v23
+      - uses: DeterminateSystems/nix-installer-action@main
+      - uses: DeterminateSystems/magic-nix-cache-action@main
       - name: test
-        uses: FrancisRussell/[email protected]
-        with:
-          command: cargo test
+        run: nix develop --command cargo test
 
   clippy:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - name: cache
-        uses: FrancisRussell/[email protected]
-        with:
-          command: cache
-      - name: toolchain
-        uses: FrancisRussell/[email protected]
-        with:
-          command: install-rustup
-          toolchain: stable
-          components: clippy
-      - name: test
-        uses: FrancisRussell/[email protected]
-        with:
-          command: cargo clippy
-          args: --all-targets -- --deny warnings
+      - uses: DeterminateSystems/nix-installer-action@main
+      - uses: DeterminateSystems/magic-nix-cache-action@main
+      - name: clippy
+        run: nix develop --command cargo clippy --all-targets -- --deny warnings
 
   fmt:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - name: toolchain
-        uses: FrancisRussell/[email protected]
-        with:
-          command: install-rustup
-          toolchain: stable
+      - uses: DeterminateSystems/nix-installer-action@main
+      - uses: DeterminateSystems/magic-nix-cache-action@main
       - name: fmt
-        uses: FrancisRussell/[email protected]
-        with:
-          command: cargo fmt
-          args: --check
+        run: nix develop --command cargo fmt --check
 
   release:
     if: ${{ github.event_name == 'push' && github.ref == 'refs/heads/main' }}

flake.nix

@@ -6,13 +6,15 @@
   inputs.fenix.url = "github:nix-community/fenix";
   inputs.flake-compat.url = "https://flakehub.com/f/edolstra/flake-compat/1.tar.gz";
   inputs.flake-utils.url = "github:numtide/flake-utils";
+  inputs.nix.url = "github:NixOS/nix/2.18.2";
 
   outputs = {
     self,
     crane,
     fenix,
     flake-compat,
     flake-utils,
+    nix,
     nixpkgs,
   }: let
     inherit (nixpkgs.lib) optional;
@@ -21,6 +23,7 @@
       pkgs = nixpkgs.legacyPackages.${system};
       toolchain = fenix.packages.${system}.stable.completeToolchain;
       craneLib = crane.lib.${system}.overrideToolchain toolchain;
+      NIX_CMD_PATH = "${nix.packages.${system}.nix}/bin/nix";
 
       commonArgs = {
         src = craneLib.cleanCargoSource (craneLib.path ./.);
@@ -32,7 +35,7 @@
       packages.default = craneLib.buildPackage (
         commonArgs
         // {
-          inherit cargoArtifacts;
+          inherit cargoArtifacts NIX_CMD_PATH;
           nativeCheckInputs = [pkgs.nix];
           # 1. integration tests execute `nix`, which fails creating `/nix/var`
           # 2. integration tests require `/dev/ptmx`
@@ -41,6 +44,7 @@
       );
 
       devShells.default = craneLib.devShell {
+        inherit NIX_CMD_PATH;
         inputsFrom = [self.packages.${system}.default];
         packages = [
           toolchain

src/expression/driver.rs

@@ -13,7 +13,6 @@ pub(crate) struct ExpressionDriver {
         ExampleId,
         futures::future::LocalBoxFuture<'static, std::io::Result<std::process::Output>>,
     )>,
-    nix_path: camino::Utf8PathBuf,
 }
 
 #[derive(Debug)]
@@ -23,16 +22,13 @@ pub(crate) enum ExpressionEvent {
 }
 
 impl ExpressionDriver {
-    pub(crate) fn new(
-        nix_path: camino::Utf8PathBuf,
-    ) -> (
+    pub(crate) fn new() -> (
         Self,
         futures::stream::LocalBoxStream<'static, ExpressionEvent>,
     ) {
         let (sender, receiver) = futures::channel::mpsc::unbounded();
         let driver = Self {
             sender,
-            nix_path,
             nix_processes: Vec::new(),
         };
         (driver, receiver.boxed_local())
@@ -75,7 +71,7 @@ impl ExpressionDriver {
     }
 
     async fn spawn_nix(&mut self, example: ExpressionExample) {
-        let task = tokio::process::Command::new(&self.nix_path)
+        let task = tokio::process::Command::new(env!("NIX_CMD_PATH"))
             .args(["eval", "--expr"])
             .arg(example.expression)
             .output();

src/main.rs

@@ -22,8 +22,6 @@ use crate::{
 #[derive(Debug, clap::Parser)]
 #[command(version, about)]
 struct Cli {
-    /// Path to a `nix` executable
-    nix_path: camino::Utf8PathBuf,
     /// pattern (`glob` crate) of markdown filespaths
     sources: String,
 }
@@ -35,8 +33,8 @@ async fn main() -> anyhow::Result<()> {
     if examples.is_empty() {
         anyhow::bail!("could not find any examples");
     }
-    let (repl_driver, repl_events) = ReplDriver::new(cli.nix_path.clone());
-    let (expression_driver, expression_events) = ExpressionDriver::new(cli.nix_path);
+    let (repl_driver, repl_events) = ReplDriver::new();
+    let (expression_driver, expression_events) = ExpressionDriver::new();
     let (eprintln_driver, eprintln_events) = EprintlnDriver::new();
 
     let inputs = Inputs {

src/repl/driver.rs

@@ -54,18 +54,14 @@ pub(crate) enum ReplEvent {
 pub(crate) struct ReplDriver {
     sessions: std::collections::BTreeMap<ExampleId, (pty_process::Pty, tokio::process::Child)>,
     sender: futures::channel::mpsc::UnboundedSender<ReplEvent>,
-    nix_path: camino::Utf8PathBuf,
 }
 
 impl ReplDriver {
-    pub(crate) fn new(
-        nix_path: camino::Utf8PathBuf,
-    ) -> (Self, futures::stream::LocalBoxStream<'static, ReplEvent>) {
+    pub(crate) fn new() -> (Self, futures::stream::LocalBoxStream<'static, ReplEvent>) {
         let (sender, receiver) = futures::channel::mpsc::unbounded::<ReplEvent>();
         let driver = Self {
             sessions: Default::default(),
             sender,
-            nix_path,
         };
         (driver, receiver.boxed_local())
     }
@@ -140,7 +136,7 @@ impl ReplDriver {
             }
         };
 
-        let child = pty_process::Command::new(&self.nix_path)
+        let child = pty_process::Command::new(env!("NIX_CMD_PATH"))
             .args(["repl", "--quiet"])
             .spawn(&pts);
 

tests/expression.rs

@@ -1,5 +1,7 @@
 mod util;
 
+use std::os::unix::fs::PermissionsExt;
+
 use assert_fs::fixture::FileWriteStr;
 use indoc::indoc;
 use predicates::{
@@ -59,14 +61,17 @@ fn io_error() {
             "})
             .unwrap();
 
+        let mut perms = file.metadata().unwrap().permissions();
+        perms.set_mode(0o000);
+        std::fs::set_permissions(&file, perms).unwrap();
+
         let mut eelco = assert_cmd::Command::cargo_bin("eelco").unwrap();
 
-        eelco.arg("brix");
         eelco.arg(file.as_os_str());
 
         eelco
             .assert()
             .failure()
-            .stderr("Error: No such file or directory (os error 2)\n");
+            .stderr(predicates::str::starts_with("Error: "));
     });
 }

tests/util/mod.rs

@@ -4,7 +4,6 @@ pub fn with_eelco(f: impl FnOnce(&mut NamedTempFile, &mut assert_cmd::Command))
     let mut tmpfile = NamedTempFile::new("we-dont-particularly-mind.md").unwrap();
     let mut command = assert_cmd::Command::cargo_bin("eelco").unwrap();
 
-    command.arg("nix");
     command.arg(tmpfile.as_os_str());
     f(&mut tmpfile, &mut command);
     drop(tmpfile);