Add test for the evaluation cache

tests/functional/flakes/eval-cache.sh

@@ -0,0 +1,22 @@
+source ./common.sh
+
+requireGit
+
+flake1Dir="$TEST_ROOT/eval-cache-flake"
+
+createGitRepo "$flake1Dir" ""
+
+cat >"$flake1Dir/flake.nix" <<EOF
+{
+  description = "Fnord";
+  outputs = { self }: {
+    foo.bar = throw "breaks";
+  };
+}
+EOF
+
+git -C "$flake1Dir" add flake.nix
+git -C "$flake1Dir" commit -m "Init"
+
+expect 1 nix build "$flake1Dir#foo.bar" 2>&1 | grepQuiet 'error: breaks'
+expect 1 nix build "$flake1Dir#foo.bar" 2>&1 | grepQuiet 'error: breaks'

tests/functional/local.mk

@@ -16,6 +16,7 @@ nix_tests = \
   flakes/build-paths.sh \
   flakes/flake-in-submodule.sh \
   flakes/prefetch.sh \
+  flakes/eval-cache.sh \
   gc.sh \
   nix-collect-garbage-d.sh \
   remote-store.sh \