feat(disconnected): function to break all pending promises

lib/captp.js

@@ -8,6 +8,7 @@ import { HandledPromise, E } from '@agoric/eventual-send';
 export { E, HandledPromise, Nat, harden };
 
 export function makeCapTP(ourId, send, bootstrapObj = undefined) {
+  let unplug = false;
   const { serialize, unserialize } = makeMarshal(
     // eslint-disable-next-line no-use-before-define
     serializeSlot,
@@ -204,6 +205,9 @@ export function makeCapTP(ourId, send, bootstrapObj = undefined) {
 
   // Return a dispatch function.
   const dispatch = obj => {
+    if (unplug) {
+      return false;
+    }
     const fn = handler[obj.type];
     if (fn) {
       fn(obj);
@@ -212,5 +216,16 @@ export function makeCapTP(ourId, send, bootstrapObj = undefined) {
     return false;
   };
 
-  return harden({ dispatch, getBootstrap });
+  const disconnected = () => {
+    unplug = true;
+    const err = Error(`${ourId} disconnected`);
+    for (const pr of questions.values()) {
+      pr.rej(err);
+    }
+    for (const pr of imports.values()) {
+      pr.rej(err);
+    }
+  };
+
+  return harden({ dispatch, getBootstrap, disconnected });
 }

test/disco.js

@@ -0,0 +1,15 @@
+import { test } from 'tape-promise/tape';
+import { harden, makeCapTP } from '../lib/captp';
+
+test('try disconnecting captp', async t => {
+  try {
+    const { dispatch, getBootstrap, disconnected } = makeCapTP('us', obj => {}, () => harden({}));
+    const pr = t.rejects(getBootstrap(), Error, 'rejected after disconnect');
+    disconnected();
+    await pr;
+  } catch (e) {
+    t.isNot(e, e, 'unexpected exception');
+  } finally {
+    t.end();
+  }
+});