d/tests/manual/1065494: Add a manual reproducer for #1065494

Based on the reproducer I added to src:glib2.0 for the similar bug #1065022.
This one is simpler, because only architecture-specific multiarch files
are affected.

debian/tests/manual/1065494.sh

@@ -0,0 +1,70 @@
+#!/bin/sh
+# Copyright 2024 Simon McVittie
+# SPDX-License-Identifier: LGPL-2.1-or-later
+
+# Reproducer for <https://bugs.debian.org/1065494>.
+# Needs to be run as root in an expendable amd64 chroot, container or VM
+# that initially has apt sources that can install some version of
+# libgtk-3-0, for example:
+# podman run --rm -it -v $(pwd):$(pwd):ro -w $(pwd) debian:bookworm-slim debian/tests/manual/1065494.sh
+# podman run --rm -it -v $(pwd):$(pwd):ro -w $(pwd) debian:sid-slim debian/tests/manual/1065494.sh
+
+set -eux
+
+export DEBIAN_FRONTEND=noninteractive
+n=0
+failed=0
+this_tuple=x86_64-linux-gnu
+
+assert () {
+    n=$(( n + 1 ))
+
+    if "$@"; then
+        echo "ok $n - $*"
+    else
+        echo "not ok $n - $* exit status $?"
+        failed=1
+    fi
+}
+
+# GTK 3 contains some IM modules, so we don't need to install a separate
+# package to get a non-empty cache.
+apt-get -y update
+apt-get -y install libgtk-3-0
+test -e "/usr/lib/$this_tuple/gtk-3.0/3.0.0/immodules.cache"
+test -s "/usr/lib/$this_tuple/gtk-3.0/3.0.0/immodules.cache"
+
+# Upgrade to current unstable, with libgtk-3-0t64
+cat > /etc/apt/sources.list.d/debian.sources <<EOF
+Types: deb
+URIs: http://deb.debian.org/debian
+Suites: sid
+Components: main
+Signed-By: /usr/share/keyrings/debian-archive-keyring.gpg
+EOF
+
+# Add a deb822-formatted apt source at this location if you are testing a
+# locally-built glib2.0 before upload
+if [ -e "debian/tests/manual/local-1065494.sources" ]; then
+    install -m644 "debian/tests/manual/local-1065494.sources" /etc/apt/sources.list.d/
+fi
+
+# Reproducer: Upgrade to libgtk-3-0t64. This runs the postrm from
+# libgtk-3-0, which deletes necessary files.
+apt-get -y update
+apt-get -y install --purge libgtk-3-0t64
+
+assert test -e "/usr/lib/$this_tuple/gtk-3.0/3.0.0/immodules.cache"
+assert test -s "/usr/lib/$this_tuple/gtk-3.0/3.0.0/immodules.cache"
+
+# Workaround: Trigger the postinst of libgtk-3-0t64, which will regenerate
+# the generated files.
+apt-get -y install --reinstall libgtk-3-0t64
+
+assert test -e "/usr/lib/$this_tuple/gtk-3.0/3.0.0/immodules.cache"
+assert test -s "/usr/lib/$this_tuple/gtk-3.0/3.0.0/immodules.cache"
+
+echo "1..$n"
+exit "$failed"
+
+# vim:set sw=4 sts=4 et: