test(tvix/glue): add nonexisting_path_without_import test r/7219

This moves the failing example from cl/10285 into its separate test
case.

There were multiple complications: tvix-[ca]store was panicking in some
places, rather than returning an error. This is now fixed.

It needs to live in tvix-glue, so we actually have a "proper" EvalIO
interface doing something.

> toString ({ line = 42; col = 42; file = /deep/thought; }.file)

Should not cause an error, because it shouldn't trigger an import, but
leave the path as-is, and not care about it not being present.

Change-Id: I76f70b3cb1f73a0fb05870375710fd9f67d5603c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10342
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: sterni <sternenseemann@systemli.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/tvix/glue/src/tvix_store_io.rs b/tvix/glue/src/tvix_store_io.rs
index 611e354414..70ec21e743 100644
--- a/tvix/glue/src/tvix_store_io.rs
+++ b/tvix/glue/src/tvix_store_io.rs
@@ -469,4 +469,22 @@ mod tests {
             import_path_and_compare(tmpdir.path().join("hello.txt"))
         );
     }
+
+    /// Invoke toString on a nonexisting file, and access the .file attribute.
+    /// This should not cause an error, because it shouldn't trigger an import,
+    /// and leave the path as-is.
+    #[test]
+    fn nonexisting_path_without_import() {
+        let result = eval("toString ({ line = 42; col = 42; file = /deep/thought; }.file)");
+
+        assert!(result.errors.is_empty(), "expect evaluation to succeed");
+        let value = result.value.expect("must be some");
+
+        match value {
+            tvix_eval::Value::String(s) => {
+                assert_eq!("/deep/thought", s.as_str());
+            }
+            _ => panic!("unexpected value type: {:?}", value),
+        }
+    }
 }