Allow overriding headless test URL (#3861)

CHANGELOG.md

@@ -17,6 +17,9 @@
 * Add support for `Option<*const T>`, `Option<*mut T>` and `NonNull<T>`.
   [#3852](https://github.com/rustwasm/wasm-bindgen/pull/3852)
 
+* Allow overriding the URL used for headless tests by setting `WASM_BINDGEN_TEST_ADDRESS`.
+  [#3861](https://github.com/rustwasm/wasm-bindgen/pull/3861)
+
 ### Changed
 
 * Allow using `'static` lifetimes in functions marked with `#[wasm_bindgen]`. This does not allow references where they were not allowed before!

crates/cli/src/bin/wasm-bindgen-test-runner/headless.rs

@@ -121,7 +121,8 @@ pub fn run(server: &SocketAddr, shell: &Shell, timeout: u64) -> Result<(), Error
 
     // Visit our local server to open up the page that runs tests, and then get
     // some handles to objects on the page which we'll be scraping output from.
-    let url = format!("http://{}", server);
+    let url =
+        std::env::var("WASM_BINDGEN_TEST_ADDRESS").unwrap_or_else(|_| format!("http://{}", server));
     shell.status(&format!("Visiting {}...", url));
     client.goto(&id, &url)?;
     shell.status("Loading page elements...");