refactor(zseri/store-ref-scanner): get rid of proc_unroll dependency

Change-Id: I0d4a8b2af814fd2870c3eb4218ee4fbaba1216f5
Reviewed-on: https://cl.tvl.fyi/c/depot/+/4605
Tested-by: BuildkiteCI
Reviewed-by: zseri <zseri.devel@ytrizja.de>

users/zseri/store-ref-scanner/tests.nix

@@ -0,0 +1,32 @@
+{ depot, lib, pkgs, ... }:
+
+let
+  parent = depot.users.zseri.store-ref-scanner;
+in
+pkgs.buildRustCrate {
+  pname = "store-ref-scanner-tests";
+  inherit (parent) crateName src version edition;
+  buildTests = true;
+  postInstall = ''
+    set -ex
+    export RUST_BACKTRACE=1
+    # recreate a file hierarchy as when running tests with cargo
+    # the source for test data
+    # build outputs
+    testRoot=target/debug
+    mkdir -p $testRoot
+    chmod +w -R .
+    # test harness executables are suffixed with a hash,
+    # like cargo does this allows to prevent name collision
+    # with the main executables of the crate
+    hash=$(basename $out)
+    ls -lasR $out
+    for file in $out/tests/*; do
+      f=$testRoot/$(basename $file)-$hash
+      cp $file $f
+      $f 2>&1 | tee -a $out/tests.log
+    done
+    rm -rf $out/tests
+    set +ex
+  '';
+}