refactor(cli/repl): get context id from notification (denoland#7864)

This takes the execution context id from a notification which is sent on
Runtime.enable rather than hard-coding it to a magic value.

cli/inspector.rs

@@ -826,6 +826,7 @@ pub struct InspectorSession {
   v8_session: v8::UniqueRef<v8::inspector::V8InspectorSession>,
   response_tx_map: HashMap<i32, oneshot::Sender<serde_json::Value>>,
   next_message_id: i32,
+  notification_queue: Vec<Value>,
 }
 
 impl Deref for InspectorSession {
@@ -868,8 +869,12 @@ impl v8::inspector::ChannelImpl for InspectorSession {
 
   fn send_notification(
     &mut self,
-    _message: v8::UniquePtr<v8::inspector::StringBuffer>,
+    message: v8::UniquePtr<v8::inspector::StringBuffer>,
   ) {
+    let raw_message = message.unwrap().string().to_string();
+    let message = serde_json::from_str(&raw_message).unwrap();
+
+    self.notification_queue.push(message);
   }
 
   fn flush_protocol_notifications(&mut self) {}
@@ -890,15 +895,22 @@ impl InspectorSession {
       let response_tx_map = HashMap::new();
       let next_message_id = 0;
 
+      let notification_queue = Vec::new();
+
       Self {
         v8_channel,
         v8_session,
         response_tx_map,
         next_message_id,
+        notification_queue,
       }
     })
   }
 
+  pub fn notifications(&mut self) -> Vec<Value> {
+    self.notification_queue.split_off(0)
+  }
+
   pub async fn post_message(
     &mut self,
     method: &str,

cli/repl.rs

@@ -89,16 +89,32 @@ pub async fn run(
   global_state: &GlobalState,
   mut worker: MainWorker,
 ) -> Result<(), AnyError> {
-  // Our inspector is unable to default to the default context id so we have to specify it here.
-  let context_id: u32 = 1;
-
   let mut session = worker.create_inspector_session();
 
   let history_file = global_state.dir.root.join("deno_history.txt");
 
   post_message_and_poll(&mut *worker, &mut session, "Runtime.enable", None)
     .await?;
 
+  // Enabling the runtime domain will always send trigger one executionContextCreated for each
+  // context the inspector knows about so we grab the execution context from that since
+  // our inspector does not support a default context (0 is an invalid context id).
+  let mut context_id: u64 = 0;
+  for notification in session.notifications() {
+    let method = notification.get("method").unwrap().as_str().unwrap();
+    let params = notification.get("params").unwrap();
+
+    if method == "Runtime.executionContextCreated" {
+      context_id = params
+        .get("context")
+        .unwrap()
+        .get("id")
+        .unwrap()
+        .as_u64()
+        .unwrap();
+    }
+  }
+
   let helper = Helper {
     validator: MatchingBracketValidator::new(),
   };