add shell.nix (#175)

Tests had to be lightly changed to support installation under Nix.

Added a Nix testing target to run all tests under Nix.

.github/workflows/test.yaml

@@ -190,6 +190,26 @@ jobs:
             ./configure
             ./install-sh
 
+  nix:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+
+      - name: Allow unprivileged user namespaces (for Ubuntu 24.04)
+        run: |
+          sudo sysctl kernel.apparmor_restrict_unprivileged_userns=0
+
+      - name: Install Nix
+        uses: DeterminateSystems/nix-installer-action@main
+
+      - name: Run tests
+        run: |
+          nix-shell --run "sh scripts/run_tests.sh"
+
+
   prerelease:
     needs:
       - test-checkout

shell.nix

@@ -0,0 +1,12 @@
+{ pkgs ? import <nixpkgs> {}}:
+
+pkgs.mkShell {
+  buildInputs = with pkgs; [
+    expect
+    mergerfs
+    attr
+    util-linux
+    time
+    shellcheck
+  ];
+}

test/explore.sh

@@ -17,15 +17,15 @@ trap 'cleanup' EXIT
 try_workspace="$(mktemp -d)"
 cd "$try_workspace" || exit 9
 
-SHELL="/bin/bash --norc"
+SHELL="/usr/bin/env bash --norc"
 export SHELL
 PS1="# "
 export PS1
 
 echo hi >expected.out
 
 cat >explore.exp <<EOF
-#!/usr/bin/expect
+#!/usr/bin/env expect
 
 set timeout 3
 

test/missing_unionfs_mergerfs.sh

@@ -21,20 +21,46 @@ cleanup() {
 
 trap 'cleanup' EXIT
 
+run_regular() {
+    new_bin_dir="$(mktemp -d)"
+    mkdir "$new_bin_dir/usr"
+    # -s makes symlinks
+    cp -rs /usr/bin "$new_bin_dir/usr/bin"
+
+    # Delete mergerfs and unionfs and set the new PATH to the temporary directory
+    rm -f "$new_bin_dir/usr/bin/mergerfs" 2>/dev/null
+    rm -f "$new_bin_dir/usr/bin/unionfs" 2>/dev/null
+
+    echo hi >expected
+    PATH="$new_bin_dir/usr/bin" "$TRY" -y "echo hi" >target 2>/dev/null || exit 1
+    diff -q expected target || exit 2
+}
+
+run_nix() {
+    cat > shell.nix <<'EOF'
+    { pkgs ? import <nixpkgs> {} }:
+    pkgs.mkShell {
+        buildInputs = with pkgs; [
+            attr
+            util-linux
+        ];
+    }
+EOF
+
+    echo hi >expected
+    # Run the command in a nix-shell with only the specified packages
+    nix-shell --pure shell.nix --run "\"$TRY\" -y \"echo hi\"" >target 2>/dev/null || exit 3
+    diff -q expected target || exit 4
+}
+
 # particularly important that we run in mktemp: in some test machines,
 # the cwd is mounted, hence inaccessable.
 try_workspace="$(mktemp -d)"
 cd "$try_workspace" || exit 9
 
-new_bin_dir="$(mktemp -d)"
-mkdir "$new_bin_dir/usr"
-# -s makes symlinks
-cp -rs /usr/bin "$new_bin_dir/usr/bin"
-
-# Delete mergerfs and unionfs and set the new PATH to the temporary directory
-rm -f "$new_bin_dir/usr/bin/mergerfs" 2>/dev/null
-rm -f "$new_bin_dir/usr/bin/unionfs" 2>/dev/null
-
-echo hi >expected
-PATH="$new_bin_dir/usr/bin" "$TRY" -y "echo hi" >target 2>/dev/null || exit 1
-diff -q expected target || exit 2
+if [ -e /etc/NIXOS ]
+then
+    run_nix
+else
+    run_regular
+fi