nix: add (failing) selfreference test for multiple realizations

The test illustrates failure in issue #5320. Here derivation and
it's built input have identical CA sotre path. As a result we generate
extraneout reference to build input:

    $ make installcheck
    ...
    ran test tests/selfref-gc.sh... [PASS]
    ran test tests/ca/selfref-gc.sh... [FAIL]
    ...
        deleting '/tmp/.../tests/ca/selfref-gc/store/iqciq1mpg5hc7p6a52fp2bjxbyc9av0v-selfref-gc'
        deleting '/tmp/...tests/ca/selfref-gc/store/zh0kwpnirw3qbv6dl1ckr1y0kd5aw6ax-selfref-gc.drv'
        error: executing SQLite statement
          'delete from ValidPaths where path = '/tmp/.../tests/ca/selfref-gc/store/fsjq0k146r85lsh01l0icl30rnhv7z72-selfref-gc';':
            constraint failed (in '/tmp/.../tests/ca/selfref-gc/var/nix/db/db.sqlite')

1 files changed, 28 insertions, 0 deletions

diff --git a/tests/selfref-gc.sh b/tests/selfref-gc.sh
new file mode 100644
index 000000000..cf1c4d18e
--- /dev/null
+++ b/tests/selfref-gc.sh
@@ -0,0 +1,28 @@
+source common.sh
+
+clearStore
+
+nix-build --no-out-link -E '
+  with import ./config.nix;
+
+  let d1 = mkDerivation {
+    name = "selfref-gc";
+    outputs = [ "out" ];
+    buildCommand = "
+      echo SELF_REF: $out > $out
+    ";
+  }; in
+
+  # the only change from d1 is d1 as an (unused) build input
+  # to get identical store path in CA.
+  mkDerivation {
+    name = "selfref-gc";
+    outputs = [ "out" ];
+    buildCommand = "
+      echo UNUSED: ${d1}
+      echo SELF_REF: $out > $out
+    ";
+  }
+'
+
+nix-collect-garbage