add failing test

.github/workflows/test.yml

@@ -52,3 +52,21 @@ jobs:
         nix_path: nixpkgs=channel:nixos-20.03
     - run: test $NIX_PATH == "nixpkgs=channel:nixos-20.03"
     - run: nix-build test.nix
+
+  extra-nix-config:
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+    - uses: actions/checkout@v2
+    - run: yarn install --frozen-lockfile
+    - run: yarn build
+    - name: Install Nix
+      uses: ./
+      with:
+        extra_nix_config: |
+          hello = world
+          # sandbox = relaxed
+    - run: cat /etc/nix/nix.conf
+    - run: nix-build test.nix --arg noChroot true

lib/install-nix.sh

@@ -5,8 +5,9 @@ set -euo pipefail
 sudo sh -c 'echo max-jobs = auto >> /tmp/nix.conf'
 # Allow binary caches for runner user
 sudo sh -c 'echo trusted-users = root runner >> /tmp/nix.conf'
+# Append extra nix configuration if provided
 if [[ -n $INPUT_EXTRA_NIX_CONFIG ]]; then
-  echo "$INPUT_EXTRA_NIX_CONFIG" >> /tmp/nix.conf
+  echo "$INPUT_EXTRA_NIX_CONFIG" | sudo tee -a /tmp/nix.conf >/dev/null
 fi
 
 install_options=(

test.nix

@@ -2,14 +2,17 @@
 { size ? 1 # MB
 , num ? 10 # count 
 , currentTime ? builtins.currentTime
+, noChroot ? false
 }:
 
 with import <nixpkgs> {};
 
 let
-  drv = i: runCommand "${toString currentTime}-${toString i}" {} ''
+  drv = i: runCommand "${toString currentTime}-${toString i}" {
+    __noChroot = noChroot;
+  } ''
     dd if=/dev/zero of=$out bs=${toString size}MB count=1
   '';
 in writeText "empty-${toString num}-${toString size}MB" ''
   ${lib.concatMapStringsSep "" drv (lib.range 1 num)}
-''
+''