test(tvix/eval): Add proof-of-concept test for Chunk

This is pretty boring at the moment, but mostly serves as a foot in the
door in the direction of writing more tests

Change-Id: Id88eb4ec7e53ebb2d5b5c254c8f45ff750238811
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6637
Autosubmit: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>

tvix/eval/src/chunk.rs

@@ -154,3 +154,17 @@ impl Chunk {
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::test_utils::dummy_span;
+
+    use super::*;
+
+    #[test]
+    fn push_op() {
+        let mut chunk = Chunk::default();
+        chunk.push_op(OpCode::OpNull, dummy_span());
+        assert_eq!(chunk.code.last().unwrap(), &OpCode::OpNull);
+    }
+}