Add CI test (#17)

.github/workflows/ci.yaml

@@ -0,0 +1,16 @@
+name: "CI"
+on:
+  # Run only when pushing to master branch, and making PRs
+  push:
+    branches:
+      - master
+  pull_request:
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Install Nix
+        uses: DeterminateSystems/nix-installer-action@main
+      - name: Test
+        run: ./test/test.sh

test/expected

@@ -0,0 +1,4 @@
+/nix/store/3k5m5hpb07bchbdymlwkn0n06vn09src-foo-0.1.0.0
+/nix/store/y5gw89k3ch5gx9aqxazxqll6g8da1j26-ghc-shell-for-packages-0
+/nix/store/zfh0052wf0ndn0033lg5x7kf4s72kfgw-bar-0.1.0.0
+/nix/store/zfh0052wf0ndn0033lg5x7kf4s72kfgw-bar-0.1.0.0/bin/bar

test/test.sh

@@ -0,0 +1,11 @@
+set -euxo pipefail
+
+cd "$(dirname "$0")"
+rm -f result
+
+nix build .. --override-input flake github:srid/haskell-multi-nix/c85563721c388629fa9e538a1d97274861bc8321 -L --no-link --print-out-paths | xargs cat | sort | uniq \
+    > result
+
+diff expected result
+
+rm -f result