feat(nix/readTree): add tests of the traversal logic in README r/2165

This should closely match the documented behaviour. It might still be
missing some edge cases of course.

Change-Id: I5c75fa045d5f3be8cf5eab787a02644500c14522
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2466
Reviewed-by: tazjin <mail@tazj.in>
Tested-by: BuildkiteCI

1 files changed, 7 insertions, 0 deletions

diff --git a/nix/readTree/tests/test-tree-traversal/default-nix/can-be-drv/default.nix b/nix/readTree/tests/test-tree-traversal/default-nix/can-be-drv/default.nix
new file mode 100644
index 000000000000..95d13d3c2750
--- /dev/null
+++ b/nix/readTree/tests/test-tree-traversal/default-nix/can-be-drv/default.nix
@@ -0,0 +1,7 @@
+{ ... }:
+derivation {
+  name = "im-a-drv";
+  system = builtins.currentSystem;
+  builder = "/bin/sh";
+  args = [ "-c" ''echo "" > $out'' ];
+}