stdenv.tests: Add succeedOnFailure

pkgs/stdenv/generic/default.nix

@@ -175,6 +175,11 @@ let
       # without running any commands. Because this will also skip `shopt -s extglob`
       # commands and extglob affects the Bash parser, we enable extglob always.
       shellDryRun = "${stdenv.shell} -n -O extglob";
+
+      tests = {
+        succeedOnFailure = import ../tests/succeedOnFailure.nix { inherit stdenv; };
+      };
+      passthru.tests = lib.warn "Use `stdenv.tests` instead. `passthru` is a `mkDerivation` detail." stdenv.tests;
     }
 
     # Propagate any extra attributes.  For instance, we use this to

pkgs/stdenv/tests/succeedOnFailure.nix

@@ -0,0 +1,14 @@
+{ stdenv }:
+
+stdenv.mkDerivation {
+  name = "stdenv-test-succeedOnFailure";
+
+  succeedOnFailure = true;
+
+  passAsFile = [ "buildCommand" ];
+  buildCommand = ''
+    mkdir $out
+    echo foo > $out/foo
+    exit 1
+  '';
+}