feat(tvix/tests): check in Nix' language test suite r/4461

This adds scaffolding code for running the Nix language test suite.

The majority of eval-okay-* tests should eventually be runnable as-is
by Tvix, however the eval-fail-* tests might not as we intend to have
more useful error messages than upstream Nix.

Change-Id: I4f3227f0889c55e4274b804a3072850fb78dd1bd
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6126
Tested-by: BuildkiteCI
Autosubmit: tazjin <tazjin@tvl.su>
Reviewed-by: grfn <grfn@gws.fyi>

1 files changed, 12 insertions, 0 deletions

diff --git a/tvix/eval/src/tests/nix_tests/eval-okay-builtins.nix b/tvix/eval/src/tests/nix_tests/eval-okay-builtins.nix
new file mode 100644
index 0000000000..e9d65e88a8
--- /dev/null
+++ b/tvix/eval/src/tests/nix_tests/eval-okay-builtins.nix
@@ -0,0 +1,12 @@
+assert builtins ? currentSystem;
+assert !builtins ? __currentSystem;
+
+let {
+
+  x = if builtins ? dirOf then builtins.dirOf /foo/bar else "";
+
+  y = if builtins ? fnord then builtins.fnord "foo" else "";
+
+  body = x + y;
+  
+}