hub/sagas: fix error message not shown when starting repl

- Add check for repl start command success/fail.
- Show error message on fail.
- Rename start repl action.
- Add new did start/did fail to start repl actions.
- Change terminal saga to use did start repl action to focus terminal.
- Add more tests.

src/terminal/sagas.test.ts

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2020-2022 The Pybricks Authors
+// Copyright (c) 2020-2023 The Pybricks Authors
 
 import PushStream from 'zen-push';
 import { AsyncSaga, delay } from '../../test';
@@ -9,7 +9,7 @@ import {
     didWrite,
     write,
 } from '../ble-nordic-uart-service/actions';
-import { checksum } from '../hub/actions';
+import { checksum, hubDidStartRepl } from '../hub/actions';
 import { HubRuntimeState } from '../hub/reducers';
 import { createCountFunc } from '../utils/iter';
 import { receiveData, sendData } from './actions';
@@ -179,3 +179,16 @@ describe('Terminal data source responds to receive data actions', () => {
         await saga.end();
     });
 });
+
+it('should focus terminal when repl is started', async () => {
+    const dispatchEventSpy = jest.spyOn(window, 'dispatchEvent');
+
+    const saga = new AsyncSaga(terminal);
+
+    saga.put(hubDidStartRepl());
+
+    // https://stackoverflow.com/a/64787979/1976323
+    expect(dispatchEventSpy.mock.calls[0][0].type).toBe('pb-terminal-focus');
+
+    await saga.end();
+});

src/terminal/sagas.ts

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2020-2022 The Pybricks Authors
+// Copyright (c) 2020-2023 The Pybricks Authors
 
 import { AnyAction } from 'redux';
 import {
@@ -20,7 +20,7 @@ import {
     write,
 } from '../ble-nordic-uart-service/actions';
 import { nordicUartSafeTxCharLength } from '../ble-nordic-uart-service/protocol';
-import { checksum, repl } from '../hub/actions';
+import { checksum, hubDidStartRepl } from '../hub/actions';
 import { HubRuntimeState } from '../hub/reducers';
 import { RootState } from '../reducers';
 import { defined } from '../utils';
@@ -109,7 +109,7 @@ function* sendTerminalData(action: ReturnType<typeof sendData>): Generator {
     dataSource.next(action.value);
 }
 
-function handleRepl(): void {
+function handleHubDidStartRepl(): void {
     dispatchEvent(new CustomEvent('pb-terminal-focus'));
 }
 
@@ -117,5 +117,5 @@ export default function* (): Generator {
     yield* takeEvery(didNotify, receiveUartData);
     yield* fork(receiveTerminalData);
     yield* takeEvery(sendData, sendTerminalData);
-    yield* takeEvery(repl, handleRepl);
+    yield* takeEvery(hubDidStartRepl, handleHubDidStartRepl);
 }