fix(js): scope fetch clients to browser contexts

crates/obscura/tests/sequential_runtime_fetch.rs

@@ -0,0 +1,89 @@
+use std::io::{Read, Write};
+
+use obscura::Browser;
+
+fn spawn_server() -> String {
+    let listener = std::net::TcpListener::bind("127.0.0.1:0").unwrap();
+    let addr = listener.local_addr().unwrap();
+    std::thread::spawn(move || {
+        for incoming in listener.incoming() {
+            let Ok(mut stream) = incoming else {
+                continue;
+            };
+            std::thread::spawn(move || {
+                let mut request = [0u8; 2048];
+                let _ = stream.read(&mut request);
+                let request = std::str::from_utf8(&request).unwrap_or("");
+                let path = request.split_whitespace().nth(1).unwrap_or("/");
+                let (content_type, body) = if path.starts_with("/api") {
+                    ("application/json", r#"{"ok":true}"#)
+                } else {
+                    (
+                        "text/html",
+                        "<!doctype html><html><head><title>fixture</title></head><body></body></html>",
+                    )
+                };
+                let response = format!(
+                    "HTTP/1.1 200 OK\r\nContent-Type: {}\r\nContent-Length: {}\r\nAccess-Control-Allow-Origin: *\r\nConnection: close\r\n\r\n{}",
+                    content_type,
+                    body.len(),
+                    body,
+                );
+                let _ = stream.write_all(response.as_bytes());
+                let _ = stream.shutdown(std::net::Shutdown::Both);
+            });
+        }
+    });
+    format!("http://{}", addr)
+}
+
+async fn run_browser(base: &str) {
+    let browser = Browser::new().unwrap();
+    let mut page = browser.new_page().await.unwrap();
+    page.goto(base).await.unwrap();
+
+    let script = format!(
+        r#"(function() {{
+            var done = 0;
+            function mark() {{
+                done += 1;
+                document.body.setAttribute('data-done', String(done));
+            }}
+            for (var i = 0; i < 8; i++) {{
+                fetch('{base}/api?fetch=' + i)
+                    .then(function(r) {{ return r.json(); }})
+                    .then(function() {{ return fetch('{base}/api?nested=' + i); }})
+                    .then(mark)
+                    .catch(function() {{}});
+            }}
+            for (var j = 0; j < 4; j++) {{
+                var xhr = new XMLHttpRequest();
+                xhr.open('GET', '{base}/api?xhr=' + j);
+                xhr.addEventListener('load', mark);
+                xhr.send();
+            }}
+        }})()"#,
+    );
+    page.evaluate(&script);
+
+    for _ in 0..20 {
+        page.settle(250).await;
+        if page.evaluate("document.body.getAttribute('data-done')") == serde_json::json!("12") {
+            break;
+        }
+    }
+    assert_eq!(
+        page.evaluate("document.body.getAttribute('data-done')"),
+        serde_json::json!("12")
+    );
+}
+
+#[tokio::test(flavor = "current_thread")]
+async fn sequential_browsers_complete_concurrent_fetch_and_xhr() {
+    std::env::set_var("OBSCURA_ALLOW_PRIVATE_NETWORK", "1");
+    let base = spawn_server();
+
+    for _ in 0..8 {
+        run_browser(&base).await;
+    }
+}