Allow plugins to send messages

Summary: Sandy plugins can now send messages to plugins. The methods and params are strongly typed in implementation and unit tests, based on the <Methods> generic of FlipperClient.

Reviewed By: nikoant

Differential Revision: D22256972

fbshipit-source-id: 549523a402949b3eb6bb4b4ca160dedb5c5e722d

desktop/flipper-plugin/src/__tests__/test-utils.node.tsx

@@ -8,14 +8,15 @@
  */
 
 import * as TestUtils from '../test-utils/test-utils';
-
 import * as testPlugin from './TestPlugin';
 
 test('it can start a plugin and lifecycle events', () => {
   const {instance, ...p} = TestUtils.startPlugin(testPlugin);
 
-  // TODO T69105011 @ts-expect-error
-  // p.bla;
+  // @ts-expect-error
+  p.bla;
+  // @ts-expect-error
+  instance.bla;
 
   // startPlugin starts connected
   expect(instance.connectStub).toBeCalledTimes(1);
@@ -59,3 +60,36 @@ test('it can render a plugin', () => {
   `);
   // TODO: test sending updates T68683442
 });
+
+test('a plugin can send messages', async () => {
+  const {instance, onSend} = TestUtils.startPlugin(testPlugin);
+
+  // By default send is stubbed
+  expect(await instance.getCurrentState()).toBeUndefined();
+  expect(onSend).toHaveBeenCalledWith('currentState', {since: 0});
+
+  // @ts-expect-error
+  onSend('bla');
+
+  // ... But we can intercept!
+  onSend.mockImplementationOnce(async (method, params) => {
+    expect(method).toEqual('currentState');
+    expect(params).toEqual({since: 0});
+    return 3;
+  });
+  expect(await instance.getCurrentState()).toEqual(3);
+});
+
+test('a plugin cannot send messages after being disconnected', async () => {
+  const {instance, disconnect} = TestUtils.startPlugin(testPlugin);
+
+  disconnect();
+  let threw = false;
+  try {
+    await instance.getCurrentState();
+  } catch (e) {
+    threw = true; // for some weird reason expect(async () => instance.getCurrentState()).toThrow(...) doesn't work today...
+    expect(e).toMatchInlineSnapshot(`[Error: Plugin is not connected]`);
+  }
+  expect(threw).toBeTruthy();
+});