Test the post-build-hook with remote builders

Regression test for #4245

tests/build-remote-input-addressed.sh

@@ -3,3 +3,31 @@ source common.sh
 file=build-hook.nix
 
 source build-remote.sh
+
+# Add a `post-build-hook` option to the nix conf.
+# This hook will be executed both for the local machine and the remote builders
+# (because they share the same config).
+registerBuildHook () {
+    # Dummy post-build-hook just to ensure that it's executed correctly.
+    # (we can't reuse the one from `$PWD/push-to-store.sh` because of
+    # https://github.com/NixOS/nix/issues/4341)
+    cat <<EOF > $TEST_ROOT/post-build-hook.sh
+#!/bin/sh
+
+echo "Post hook ran successfully"
+# Add an empty line to a counter file, just to check that this hook ran properly
+echo "" >> $TEST_ROOT/post-hook-counter
+EOF
+    chmod +x $TEST_ROOT/post-build-hook.sh
+    rm -f $TEST_ROOT/post-hook-counter
+
+    echo "post-build-hook = $TEST_ROOT/post-build-hook.sh" >> $NIX_CONF_DIR/nix.conf
+}
+
+registerBuildHook
+source build-remote.sh
+
+# `build-hook.nix` has four derivations to build, and the hook runs twice for
+# each derivation (once on the builder and once on the host), so the counter
+# should contain eight lines now
+[[ $(cat $TEST_ROOT/post-hook-counter | wc -l) -eq 8 ]]

tests/build-remote.sh

@@ -14,6 +14,9 @@ builders=(
   "ssh-ng://localhost?remote-store=$TEST_ROOT/machine3?system-features=baz - - 1 1 baz"
 )
 
+chmod -R +w $TEST_ROOT/machine* || true
+rm -rf $TEST_ROOT/machine* || true
+
 # Note: ssh://localhost bypasses ssh, directly invoking nix-store as a
 # child process. This allows us to test LegacySSHStore::buildDerivation().
 # ssh-ng://... likewise allows us to test RemoteStore::buildDerivation().