From 9ee9d22addfda4291b1ecf99efdeab265cf80f8c Mon Sep 17 00:00:00 2001
From: dwiekawki <dwiekawki@users.noreply.github.com>
Date: Wed, 5 Feb 2025 12:17:24 +0300
Subject: [PATCH] feat(gen): fix `Felt` to always match the regex

---
 src/gen.rs   | 19 +++++++++++++++++++
 tests/exe.rs | 20 ++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/src/gen.rs b/src/gen.rs
index be4687a0..a2a315da 100644
--- a/src/gen.rs
+++ b/src/gen.rs
@@ -1002,8 +1002,27 @@ pub mod gen {
                 .expect("Felt: valid regex")
         });
 
+        // The RPC spec regex is not respected anywhere these days,
+        // thus such un-elegant workaround is necessary ¯\_(ツ)_/¯
+        fn fix(value: &str) -> String {
+            let unprefixed = value.strip_prefix("0x").unwrap_or(value);
+            if unprefixed.is_empty() {
+                // '0x'
+                "0x0".to_owned()
+            } else if unprefixed == "0" {
+                value.to_owned()
+            } else if unprefixed.starts_with("0") {
+                // '0x0...'
+                let unzeroed = unprefixed.trim_start_matches('0');
+                format!("0x{unzeroed}")
+            } else {
+                value.to_owned()
+            }
+        }
+
         impl Felt {
             pub fn try_new(value: &str) -> Result<Self, jsonrpc::Error> {
+                let value = &fix(value);
                 if FELT_REGEX.is_match(value) {
                     Ok(Self(value.to_string()))
                 } else {
diff --git a/tests/exe.rs b/tests/exe.rs
index d37256df..229b1c0d 100644
--- a/tests/exe.rs
+++ b/tests/exe.rs
@@ -64,6 +64,26 @@ fn test_call_regular_contract_class() -> Result<(), Error> {
     Ok(())
 }
 
+#[test]
+fn test_issue861() -> Result<(), Error> {
+    let client = client!();
+
+    let json = serde_json::json!({
+        "calldata": [],
+        "contract_address": "0x49d36570d4e46f48e99674bd3fcc84644ddd6b96f7c741b1562b82f9e004dc7",
+        "entry_point_selector": "0x01557182e4359a1f0c6301278e8f5b35a776ab58d39892581e357578fb287836"
+    });
+    let function_call: FunctionCall = serde_json::from_value(json)?;
+
+    let state = get_latest_state(&client);
+    let call_info = call(client, function_call, state)?;
+
+    assert_eq!(call_info.execution.retdata.0.len(), 2);
+    assert_eq!(call_info.execution.retdata.0[1].to_hex_string(), "0x0");
+
+    Ok(())
+}
+
 fn get_state(client: &Client<Http>, block_id: gen::BlockId) -> State {
     let block = client.getBlockWithTxHashes(block_id).unwrap();
     let gen::GetBlockWithTxHashesResult::BlockWithTxHashes(block) = block