Write test, will fail until rest of PR

tests/experimental-features.sh

@@ -0,0 +1,23 @@
+source common.sh
+
+# Without flakes, flake options should not show up
+# With flakes, flake options should show up
+
+function both_ways {
+    nix --experimental-features 'nix-command' "$@" | grepQuietInverse flake
+    nix --experimental-features 'nix-command flakes' "$@" | grepQuiet flake
+
+    # Also, the order should not matter
+    nix "$@" --experimental-features 'nix-command' | grepQuietInverse flake
+    nix "$@" --experimental-features 'nix-command flakes' | grepQuiet flake
+}
+
+# Simple case, the configuration effects the running command
+both_ways show-config
+
+# Complicated case, earlier args effect later args
+
+both_ways store gc --help
+
+expect 1 nix --experimental-features 'nix-command' show-config --flake-registry 'https://no'
+nix --experimental-features 'nix-command flakes' show-config --flake-registry 'https://no'

tests/local.mk

@@ -18,6 +18,7 @@ nix_tests = \
   gc.sh \
   remote-store.sh \
   lang.sh \
+  experimental-features.sh \
   fetchMercurial.sh \
   gc-auto.sh \
   user-envs.sh \