Test RUSTFLAGS addition

tests/rustflags/main.fmf

@@ -0,0 +1,7 @@
+summary: Test that conditional support for RUSTFLAGS works
+
+require:
+  - redhat-rpm-config
+  - rpm
+  - rust-packaging
+test: ./runtest.sh

tests/rustflags/runtest.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/bash
+set -e -u -o pipefail
+
+# Allow for local testing
+rargs=()
+if [ -n "${MACROS_PATH:-}" ]; then
+    default_macros_path="$(rpm --showrc | grep 'Macro path' | awk -F ': ' '{print $2}')"
+    rargs+=("--macros" "${default_macros_path}:${MACROS_PATH}")
+fi
+
+build_rustflags="$(rpm -E '%{build_rustflags}')"
+# For good measure
+[ "${build_rustflags}" != "%{build_rustflags}" ]
+#
+flags="$(rpm "${rargs[@]}" -E '%set_build_flags')"
+
+echo 'Check that RUSTFLAGS is set after evaluating %set_build_flags'
+(
+    eval "${flags}"
+    # set -u will make this fail if $RUSTFLAGS isn't defined
+    [ "${RUSTFLAGS}" = "${build_rustflags}" ]
+)