Command processing (2/n): testing

Summary:
*Stack summary*: this stack refactors plugin management actions to perform them in a dispatcher rather than in the root reducer (store.tsx) as all of these actions has side effects. To do that, we store requested plugin management actions (install/update/uninstall, star/unstar) in a queue which is then handled by pluginManager dispatcher. This dispatcher then dispatches all required state updates.

*Diff summary*: refactored Flipper mocking helpers to allow testing of plugin commands, and wrote some tests for pluginManager.

Reviewed By: mweststrate

Differential Revision: D26450344

fbshipit-source-id: 0e8414517cc1ad353781dffd7ffb4a5f9a815d38

desktop/app/src/dispatcher/pluginManager.tsx

@@ -35,15 +35,29 @@ function refreshInstalledPlugins(store: Store) {
     .then((plugins) => store.dispatch(registerInstalledPlugins(plugins)));
 }
 
-export default (store: Store, _logger: Logger) => {
+export default (
+  store: Store,
+  _logger: Logger,
+  {runSideEffectsSynchronously}: {runSideEffectsSynchronously: boolean} = {
+    runSideEffectsSynchronously: false,
+  },
+) => {
   // This needn't happen immediately and is (light) I/O work.
-  window.requestIdleCallback(() => {
-    refreshInstalledPlugins(store);
-  });
+  if (window.requestIdleCallback) {
+    window.requestIdleCallback(() => {
+      refreshInstalledPlugins(store);
+    });
+  }
 
-  sideEffect(
+  const unsubscribeHandlePluginCommands = sideEffect(
     store,
-    {name: 'handlePluginActivation', throttleMs: 1000, fireImmediately: true},
+    {
+      name: 'handlePluginCommands',
+      throttleMs: 0,
+      fireImmediately: true,
+      runSynchronously: runSideEffectsSynchronously, // Used to simplify writing tests, if "true" passed, the all side effects will be called synchronously and immediately after changes
+      noTimeBudgetWarns: true, // These side effects are critical, so we're doing them with zero throttling and want to avoid unnecessary warns
+    },
     (state) => state.pluginManager.pluginCommandsQueue,
     (queue, store) => {
       for (const command of queue) {
@@ -59,6 +73,9 @@ export default (store: Store, _logger: Logger) => {
       store.dispatch(pluginCommandsProcessed(queue.length));
     },
   );
+  return async () => {
+    unsubscribeHandlePluginCommands();
+  };
 };
 
 function loadPlugin(store: Store, payload: LoadPluginActionPayload) {