Added usePlugin hooks

Summary:
`usePlugin(pluginFactory)` returns the current plugin instance's api that was exposed by the plugin directory.

Passing `pluginFactory` is technically strictly not needed, but having the user pass it, we can make sure it is strongly typed

Reviewed By: nikoant

Differential Revision: D22286293

fbshipit-source-id: 4268b6849b8cd3d524103de7eadbd6c0a65c7a61

desktop/app/src/__tests__/PluginContainer.node.tsx

@@ -16,6 +16,7 @@ import {
   SandyPluginDefinition,
   FlipperClient,
   TestUtils,
+  usePlugin,
 } from 'flipper-plugin';
 import {selectPlugin} from '../reducers/connections';
 
@@ -92,8 +93,17 @@ test('PluginContainer can render Sandy plugins', async () => {
 
   function MySandyPlugin() {
     renders++;
-    const sandyContext = useContext(SandyPluginContext);
-    expect(sandyContext).not.toBe(null);
+    const sandyApi = usePlugin(plugin);
+    expect(Object.keys(sandyApi)).toEqual([
+      'connectedStub',
+      'disconnectedStub',
+    ]);
+    expect(() => {
+      // eslint-disable-next-line
+      usePlugin(function bla() {
+        return {};
+      });
+    }).toThrowError(/didn't match the type of the requested plugin/);
     return <div>Hello from Sandy</div>;
   }
 

desktop/flipper-plugin/src/__tests__/TestPlugin.tsx

@@ -9,6 +9,7 @@
 
 import * as React from 'react';
 import {FlipperClient} from '../plugin/Plugin';
+import {usePlugin} from '../plugin/PluginContext';
 
 type Events = {
   inc: {
@@ -67,6 +68,11 @@ export function plugin(client: FlipperClient<Events, Methods>) {
 }
 
 export function Component() {
-  // TODO T69105011 add test for usePlugin including type assertions
-  return <h1>Hi from test plugin</h1>;
+  const api = usePlugin(plugin);
+
+  // @ts-expect-error
+  api.bla;
+
+  // TODO N.b.: state updates won't be visible
+  return <h1>Hi from test plugin {api.state.count}</h1>;
 }

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

@@ -54,6 +54,7 @@ test('it can render a plugin', () => {
       <div>
         <h1>
           Hi from test plugin 
+          0
         </h1>
       </div>
     </body>

desktop/flipper-plugin/src/index.ts

@@ -12,7 +12,7 @@ import * as TestUtilites from './test-utils/test-utils';
 export {SandyPluginInstance, FlipperClient} from './plugin/Plugin';
 export {SandyPluginDefinition} from './plugin/SandyPluginDefinition';
 export {SandyPluginRenderer} from './plugin/PluginRenderer';
-export {SandyPluginContext} from './plugin/PluginContext';
+export {SandyPluginContext, usePlugin} from './plugin/PluginContext';
 
 // It's not ideal that this exists in flipper-plugin sources directly,
 // but is the least pain for plugin authors.

desktop/flipper-plugin/src/plugin/PluginContext.tsx

@@ -7,9 +7,28 @@
  * @format
  */
 
-import {createContext} from 'react';
-import {SandyPluginInstance} from './Plugin';
+import {createContext, useContext} from 'react';
+import {SandyPluginInstance, FlipperPluginFactory} from './Plugin';
 
 export const SandyPluginContext = createContext<
   SandyPluginInstance | undefined
 >(undefined);
+
+export function usePlugin<PluginFactory extends FlipperPluginFactory<any, any>>(
+  plugin: PluginFactory,
+): ReturnType<PluginFactory> {
+  const pluginInstance = useContext(SandyPluginContext);
+  if (!pluginInstance) {
+    throw new Error('Plugin context not available');
+  }
+  // In principle we don't *need* the plugin, but having it passed it makes sure the
+  // return of this function is strongly typed, without the user needing to create it's own
+  // context.
+  // But since we pass it, let's make sure the user did request the proper context
+  if (pluginInstance.definition.module.plugin !== plugin) {
+    throw new Error(
+      `Plugin context (${pluginInstance.definition.module.plugin}) didn't match the type of the requested plugin (${plugin})`,
+    );
+  }
+  return pluginInstance.instanceApi;
+}