Add a test for the remote caching of CA derivations

tests/ca/substitute.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+
+# Ensure that binary substitution works properly with ca derivations
+
+source common.sh
+
+sed -i 's/experimental-features .*/& ca-derivations ca-references/' "$NIX_CONF_DIR"/nix.conf
+
+export REMOTE_STORE=file://$TEST_ROOT/binary_cache
+
+buildDrvs () {
+    nix build --file ./content-addressed.nix -L --no-link "$@"
+}
+
+# Populate the remote cache
+buildDrvs --post-build-hook ../push-to-store.sh
+
+# Restart the build on an empty store, ensuring that we don't build
+clearStore
+buildDrvs --substitute --substituters $REMOTE_STORE --no-require-sigs -j0
+