[Bug] Test hangs when mining many blocks

[jorgemmsilva]

Component

node-bindings

What version of Alloy are you on?

latest

Operating System

macOS (Apple Silicon)

Describe the bug

I found a regression when updating alloy from 0.9.2 to 0.11.0.

wrote a small test that reproduces the issue:

    #[tokio::test]
    async fn test_mine_many_blocks() {
        // 328 passes, 329 fails
        let blocks_to_mine = 329;

        let args =
            vec!["--base-fee", "0", "--gas-limit", "30000000", "--timestamp", "999", "--no-mining"];
        let anvil = alloy_node_bindings::Anvil::new().args(args).spawn();
        let provider = ProviderBuilder::new().on_http(anvil.endpoint_url());

        let head =
            provider.get_block(alloy_eips::BlockId::latest(), false.into()).await.unwrap().unwrap();
        assert_eq!(head.header.number, 0);
        let ts = head.header.timestamp;

        // Mine N blocks using anvil_mine_detailed
        for i in 0..blocks_to_mine {
            let mine_options =
                MineOptions::Options { timestamp: Some(ts + i + 1), blocks: Some(1) };
            provider.anvil_mine_detailed(Some(mine_options)).await.unwrap();
        }

        // Verify block number is at least 1000
        let final_block = provider.get_block_number().await.unwrap();
        assert!(
            final_block >= blocks_to_mine,
            "Expected at least {} blocks, got {}",
            blocks_to_mine,
            final_block
        );
    }

For some reason, on the latest version, that test will hang forever if I try to mine 329+ blocks. With less blocks, it passes.

I bissected this behavior and found the following:

70df381dd5ae09133137bd8c51b5c7f3530445c9 is the first bad commit
commit 70df381dd5ae09133137bd8c51b5c7f3530445c9 (HEAD)
Author: Yash Atreya <[email protected]>
Date:   Thu Jan 16 00:00:21 2025 +0530

    fix(`node-bindings`): reset `child.stdout` in `AnvilInstance` (#1920)
    
    * feat(`node-bindings`): expose `stdout` reader
    
    * remove reader and reset child.stdout
    
    * Update crates/node-bindings/src/nodes/anvil.rs
    
    ---------
    
    Co-authored-by: DaniPopes <[email protected]>

 crates/node-bindings/src/nodes/anvil.rs |  4 +++-
 crates/provider/src/provider/trait.rs   | 28 +++++++++++++++++++++++++++-
 2 files changed, 30 insertions(+), 2 deletions(-)

removing this line seems to fix the issue.

Please assist 🙏

[mattsse]

yeah this pr doesn't look right

#1920

this will now fill the stdout buffer and blocks, checking