Hook recover() to call browser()

The `recover()` functionality is provided by the call stack panes of
frontends

Author: lionel-

crates/ark/src/modules/positron/hooks.R

@@ -14,6 +14,17 @@ register_hooks <- function() {
         new_ark_debug(base::debugonce),
         namespace = TRUE
     )
+
+    # We don't support `utils::recover()` in Ark, but the same functionality is
+    # provided via the call stack pane of IDEs. So replace it by `browser()` so
+    # that people can enter the debugger on error using the familiar
+    # `options(error = recover)` gesture.
+    rebind(
+        "utils",
+        "recover",
+        browser,
+        namespace = TRUE
+    )
     register_getHook_hook()
 }
 

crates/ark/tests/kernel.rs

@@ -892,6 +892,34 @@ Are you calling `readline()` or `menu()` from `options(error = )`?
 }
 
 #[test]
+fn test_execute_request_error_recover() {
+    let frontend = DummyArkFrontend::lock();
+
+    let code = r#"
+f <- function() g()
+g <- function() h()
+h <- function() stop("foo")
+options(error = recover)
+"#;
+    frontend.execute_request_invisibly(code);
+
+    frontend.send_execute_request("f()", ExecuteRequestOptions::default());
+    frontend.recv_iopub_busy();
+    let input = frontend.recv_iopub_execute_input();
+    assert_eq!(input.code, "f()");
+
+    // We set up the call stack to show a simple `error_handler()`
+    frontend.recv_iopub_stream_stdout("Called from: error_handler()\n");
+
+    assert!(frontend.recv_iopub_execute_error().contains("foo"));
+
+    frontend.recv_iopub_idle();
+    assert_eq!(
+        frontend.recv_shell_execute_reply_exception(),
+        input.execution_count
+    );
+}
+
 /// Install a SIGINT handler for shutdown tests. This overrides the test runner
 /// handler so it doesn't cancel our test.
 fn install_sigint_handler() {