tests/functional: add reject features test

tests/functional/build-hook.nix

@@ -69,12 +69,31 @@ let
     requiredSystemFeatures = [ "baz" ];
   };
 
+  input4 = mkDerivation {
+    shell = busybox;
+    name = "build-remote-input-4";
+    buildCommand = ''
+      echo hi-input3
+      read x < ${input3}
+      echo $x BAZ > $out
+    '';
+    rejectSystemFeatures = [ "bar" ];
+    requiredSystemFeatures = [ "foo" ];
+  };
+
 in
 
 mkDerivation {
   shell = busybox;
   name = "build-remote";
-  passthru = { inherit input1 input2 input3; };
+  passthru = {
+    inherit
+      input1
+      input2
+      input3
+      input4
+      ;
+  };
   buildCommand = ''
     read x < ${input1}
     read y < ${input3}

tests/functional/build-remote.sh

@@ -23,6 +23,7 @@ builders=(
   "ssh://localhost?remote-store=$TEST_ROOT/machine1?system-features=$(join_by "%20" foo "${EXTRA_SYSTEM_FEATURES[@]}") - - 1 1 $(join_by "," foo "${EXTRA_SYSTEM_FEATURES[@]}")"
   "$TEST_ROOT/machine2 - - 1 1 $(join_by "," bar "${EXTRA_SYSTEM_FEATURES[@]}")"
   "ssh-ng://localhost?remote-store=$TEST_ROOT/machine3?system-features=$(join_by "%20" baz "${EXTRA_SYSTEM_FEATURES[@]}") - - 1 1 $(join_by "," baz "${EXTRA_SYSTEM_FEATURES[@]}")"
+  "$TEST_ROOT/machine4 - - 1 1 $(join_by "," bar foo "${EXTRA_SYSTEM_FEATURES[@]}")"
 )
 
 chmod -R +w "$TEST_ROOT/machine"* || true
@@ -70,6 +71,12 @@ echo "$output" | grepQuietInverse builder-build-remote-input-2.sh
 echo "$output" | grepQuiet builder-build-remote-input-3.sh
 unset output
 
+# Ensure that input4 was built on store4 due to the required feature.
+output=$(nix path-info --store "$TEST_ROOT/machine4" --all)
+echo "$output" | grepQuietInverse builder-build-remote-input-1.sh
+echo "$output" | grepQuietInverse builder-build-remote-input-2.sh
+echo "$output" | grepQuietInverse builder-build-remote-input-3.sh
+unset output
 
 for i in input1 input3; do
 nix log --store "$TEST_ROOT/machine0" --file "$file" --arg busybox "$busybox" "passthru.$i" | grep hi-$i