test(tvix/castore/path): test the null byte case

Change-Id: Ia4ceaf56f6cb4d8ed1ad935c77b3898d711da73a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11568
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>

tvix/castore/src/path.rs

@@ -208,6 +208,7 @@ mod test {
     #[case::dotdot_middle("a/../b")]
     #[case::dot_end("a/b/.")]
     #[case::dotdot_end("a/b/..")]
+    #[case::null("fo\0o")]
     pub fn from_str_fail(#[case] s: &str) {
         s.parse::<PathBuf>().expect_err("must fail");
     }