add: unit and integration testing

app/node_modules/@parcel/watcher/index.d.ts

@@ -0,0 +1,49 @@
+declare type FilePath = string;
+declare type GlobPattern = string;
+
+declare namespace ParcelWatcher {
+  export type BackendType =
+    | 'fs-events'
+    | 'watchman'
+    | 'inotify'
+    | 'windows'
+    | 'brute-force';
+  export type EventType = 'create' | 'update' | 'delete';
+  export interface Options {
+    ignore?: (FilePath | GlobPattern | RegExp)[];
+    backend?: BackendType;
+  }
+  export type SubscribeCallback = (
+    err: Error | null,
+    events: Event[],
+  ) => unknown;
+  export interface AsyncSubscription {
+    unsubscribe(): Promise<void>;
+  }
+  export interface Event {
+    path: FilePath;
+    type: EventType;
+  }
+  export function getEventsSince(
+    dir: FilePath,
+    snapshot: FilePath,
+    opts?: Options,
+  ): Promise<Event[]>;
+  export function subscribe(
+    dir: FilePath,
+    fn: SubscribeCallback,
+    opts?: Options,
+  ): Promise<AsyncSubscription>;
+  export function unsubscribe(
+    dir: FilePath,
+    fn: SubscribeCallback,
+    opts?: Options,
+  ): Promise<void>;
+  export function writeSnapshot(
+    dir: FilePath,
+    snapshot: FilePath,
+    opts?: Options,
+  ): Promise<FilePath>;
+}
+
+export = ParcelWatcher;