refactor(nix/buildLisp/tests/argv0): use derivation for tests

There is no need to use an extraStep, actually, and using derivations
reduces noise on CI.

Change-Id: I897c3c3f7e0acee8f051fcc01450ff57176726f8
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6573
Autosubmit: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>

nix/buildLisp/tests/argv0.nix

@@ -1,6 +1,9 @@
-{ depot, pkgs, ... }:
+{ depot, pkgs, lib, ... }:
 
-depot.nix.buildLisp.program {
+let
+  # Trivial test program that outputs argv[0] and exits
+  prog =
+    depot.nix.buildLisp.program {
       name = "argv0-test";
 
       srcs = [
@@ -19,18 +22,37 @@ depot.nix.buildLisp.program {
           default = depot.nix.buildLisp.bundled "asdf";
         }
       ];
+    };
 
-  passthru.meta.ci = {
-    extraSteps.verify = {
-      label = "verify argv[0] output";
-      needsOutput = true;
-      command = pkgs.writeShellScript "check-argv0" ''
+  # Extract verify argv[0] output for given buildLisp program
+  checkImplementation = prog:
+    pkgs.runCommand "check-argv0" { } ''
       set -eux
 
-        for invocation in "$(pwd)/result/bin/argv0-test" "./result/bin/argv0-test"; do
+      checkInvocation() {
+        invocation="$1"
         test "$invocation" = "$("$invocation")"
-        done
+      }
+
+      checkInvocation "${prog}/bin/argv0-test"
+
+      cd ${prog}
+      checkInvocation "./bin/argv0-test"
+
+      cd bin
+      checkInvocation ./argv0-test
+
+      set +x
+
+      touch "$out"
     '';
-    };
-  };
-}
+
+  inherit (prog.meta.ci) targets;
+in
+
+(checkImplementation prog).overrideAttrs (_: {
+  # Wire up a subtarget all (active) non-default implementations
+  passthru = lib.genAttrs targets (name: checkImplementation prog.${name});
+
+  meta.ci = { inherit targets; };
+})