Add regression test for deadlocking rayon

Author: HeroicKatora

Cargo.toml

@@ -27,6 +27,10 @@ harness = false
 name = "large_image"
 harness = false
 
+[[test]]
+name = "rayon"
+required-features = ["rayon"]
+
 [features]
 default = ["rayon"]
 platform_independent = []

tests/rayon.rs

@@ -0,0 +1,16 @@
+use std::{fs::File, path::Path};
+use jpeg_decoder::Decoder;
+
+#[test]
+fn decoding_in_limited_threadpool_does_not_deadlock() {
+    let path = Path::new("tests").join("reftest").join("images").join("mozilla").join("jpg-progressive.jpg");
+
+    let pool = rayon::ThreadPoolBuilder::new()
+        .num_threads(1)
+        .build()
+        .unwrap();
+    pool.install(|| {
+        let mut decoder = Decoder::new(File::open(&path).unwrap());
+        let _ = decoder.decode().unwrap();
+    });
+}