test: refactor rpc_regression_tests into individual tests

build.rs

@@ -1,6 +1,8 @@
 // Copyright 2019-2025 ChainSafe Systems
 // SPDX-License-Identifier: Apache-2.0, MIT
 
+use std::io::Write;
+
 fn main() {
     // whitelist the cfg for cargo clippy
     println!("cargo::rustc-check-cfg=cfg(f3sidecar)");
@@ -30,6 +32,8 @@ fn main() {
             // })
             .build();
     }
+
+    rpc_regression_tests_gen();
 }
 
 // See <https://docs.rs/about/builds#detecting-docsrs>
@@ -44,3 +48,38 @@ fn is_sidecar_ffi_enabled() -> bool {
         _ => true,
     }
 }
+
+fn rpc_regression_tests_gen() {
+    use std::{fs::File, io::BufWriter, path::PathBuf};
+
+    println!("cargo:rerun-if-changed=src/tool/subcommands/api_cmd/test_snapshots.txt");
+
+    let tests: Vec<&str> = include_str!("src/tool/subcommands/api_cmd/test_snapshots.txt")
+        .lines()
+        .map(str::trim)
+        .filter(|l| !l.is_empty() && !l.starts_with('#'))
+        .collect();
+    let out_dir = PathBuf::from(std::env::var("OUT_DIR").unwrap());
+    let out_path = out_dir.join("__rpc_regression_tests_gen.rs");
+    let mut w = BufWriter::new(File::create(&out_path).unwrap());
+    for test in tests {
+        // Derive a valid Rust identifier from the snapshot filename.
+        let ident = test
+            .strip_suffix(".rpcsnap.json.zst")
+            .unwrap_or(test)
+            .chars()
+            .map(|c| if c.is_ascii_alphanumeric() { c } else { '_' })
+            .collect::<String>();
+
+        writeln!(
+            w,
+            r#"
+                #[tokio::test(flavor = "multi_thread")]
+                async fn rpc_test_{ident}() {{
+                    rpc_regression_test_run("{test}").await
+                }}
+            "#,
+        )
+        .unwrap();
+    }
+}

src/tool/subcommands/api_cmd/test_snapshot.rs

@@ -184,68 +184,55 @@ mod tests {
     use crate::utils::net::{DownloadFileOption, download_file_with_cache};
     use crate::utils::proofs_api::ensure_proof_params_downloaded;
     use ahash::HashSet;
+    use anyhow::Context as _;
     use directories::ProjectDirs;
-    use futures::{StreamExt, stream::FuturesUnordered};
-    use itertools::Itertools as _;
+    use std::sync::LazyLock;
     use std::time::Instant;
-    use tokio::sync::Semaphore;
+    use tokio::sync::Mutex;
     use url::Url;
 
-    #[tokio::test(flavor = "multi_thread")]
-    async fn rpc_regression_tests() {
+    // To run a single test: cargo test --lib -- --nocapture --test filecoin_multisig_statedecodeparams_1754230255631789
+    include!(concat!(env!("OUT_DIR"), "/__rpc_regression_tests_gen.rs"));
+
+    async fn rpc_regression_test_run(name: &str) {
         // Skip for debug build on CI as the downloading is slow and flaky
         if crate::utils::is_ci() && crate::utils::is_debug_build() {
             return;
         }
+
         // Set proof parameter data dir and make sure the proofs are available
-        crate::utils::proofs_api::maybe_set_proofs_parameter_cache_dir_env(
-            &Config::default().client.data_dir,
-        );
-        ensure_proof_params_downloaded().await.unwrap();
-        let urls = include_str!("test_snapshots.txt")
-            .trim()
-            .split("\n")
-            .filter_map(|n| {
-                Url::parse(
-                    format!(
-                        "https://forest-snapshots.fra1.cdn.digitaloceanspaces.com/rpc_test/{n}"
-                    )
-                    .as_str(),
-                )
-                .ok()
-                .map(|url| (n, url))
-            })
-            .collect_vec();
+        {
+            static PROOF_PARAMS_LOCK: LazyLock<Mutex<()>> = LazyLock::new(|| Mutex::new(()));
+            let _guard = PROOF_PARAMS_LOCK.lock().await;
+            crate::utils::proofs_api::maybe_set_proofs_parameter_cache_dir_env(
+                &Config::default().client.data_dir,
+            );
+            ensure_proof_params_downloaded().await.unwrap();
+        }
+        let url: Url =
+            format!("https://forest-snapshots.fra1.cdn.digitaloceanspaces.com/rpc_test/{name}")
+                .parse()
+                .with_context(|| format!("Failed to parse URL for test: {name}"))
+                .unwrap();
         let project_dir = ProjectDirs::from("com", "ChainSafe", "Forest").unwrap();
         let cache_dir = project_dir.cache_dir().join("test").join("rpc-snapshots");
-        let semaphore = Arc::new(Semaphore::new(4));
-        let mut tasks = FuturesUnordered::from_iter(urls.into_iter().map(|(filename, url)| {
-            let cache_dir = cache_dir.clone();
-            let semaphore = semaphore.clone();
-            async move {
-                let _permit = semaphore.acquire().await.unwrap();
-                let result =
-                    download_file_with_cache(&url, &cache_dir, DownloadFileOption::NonResumable)
-                        .await
-                        .unwrap();
-                (filename, result.path)
-            }
-        }));
+        let path = download_file_with_cache(&url, &cache_dir, DownloadFileOption::NonResumable)
+            .await
+            .unwrap()
+            .path;
 
         // We need to set RNG seed so that tests are run with deterministic
         // output. The snapshots should be generated with a node running with the same seed, if
         // they are testing methods that are not deterministic, e.g.,
         // `[`crate::rpc::methods::gas::estimate_gas_premium`]`.
         unsafe { std::env::set_var(crate::utils::rand::FIXED_RNG_SEED_ENV, "4213666") };
-        while let Some((filename, file_path)) = tasks.next().await {
-            print!("Testing {filename} ...");
-            let start = Instant::now();
-            run_test_from_snapshot(&file_path).await.unwrap();
-            println!(
-                "  succeeded, took {}.",
-                humantime::format_duration(start.elapsed())
-            );
-        }
+        print!("Testing {name} ...");
+        let start = Instant::now();
+        run_test_from_snapshot(&path).await.unwrap();
+        println!(
+            "  succeeded, took {}.",
+            humantime::format_duration(start.elapsed())
+        );
     }
 
     #[test]