zkVK methods return public values (#106)

tests/openvm/basic/Cargo.toml

@@ -6,5 +6,6 @@ edition = "2021"
 [workspace]
 
 [dependencies]
+bincode = "1.3.3"
 openvm = { git = "https://github.com/openvm-org/openvm.git", features = ["std"], tag = "v1.2.0" }
 test-utils = { path = "../../../crates/test-utils" }

tests/openvm/basic/src/main.rs

@@ -1,16 +1,30 @@
+use core::array::from_fn;
 use openvm::io::{read, read_vec, reveal_u32};
-use test_utils::guest::BasicStruct;
+use test_utils::guest::{BasicStruct, BASIC_PROGRAM_BYTES_LENGTH};
 
 fn main() {
-    // Read `Hello world` bytes.
+    // Read `bytes`.
     let bytes = read_vec();
-    assert_eq!(String::from_utf8_lossy(&bytes), "Hello world");
 
-    // Read `BasicStruct`.
+    // Read `basic_struct`.
     let basic_struct = read::<BasicStruct>();
-    let output = basic_struct.output();
 
-    output.chunks(4).enumerate().for_each(|(idx, bytes)| {
-        reveal_u32(u32::from_le_bytes(bytes.try_into().unwrap()), idx);
-    });
+    // Check `bytes` length is as expected.
+    assert_eq!(bytes.len(), BASIC_PROGRAM_BYTES_LENGTH);
+
+    // Do some computation on `basic_struct`.
+    let basic_struct_output = basic_struct.output();
+
+    // Write reversed `bytes` and `basic_struct_output`
+    let public_values = core::iter::empty()
+        .chain(bytes.into_iter().rev())
+        .chain(bincode::serialize(&basic_struct_output).unwrap())
+        .collect::<Vec<_>>();
+    public_values
+        .chunks(4)
+        .enumerate()
+        .for_each(|(idx, bytes)| {
+            let bytes = from_fn(|i| bytes.get(i).copied().unwrap_or_default());
+            reveal_u32(u32::from_le_bytes(bytes), idx);
+        });
 }