fix Yauzl typings (#12)

Both `open` and `openReadStream` have overloads, so `promisify`
can't know which one to choose and chooses the last one (which
doesn't include options).  Additionally, once we specify those two
overloads, optional args become `arg | undefined` which is subtly
different than not providing an arg (which is what we want to be
able to do), so we specify onEntry's `openReadStream` callback
explicitly as well (to have options be optional).

I think this last point is also why we can't just update `yauzl`'s
types to have both `options` and `callback` be optional, because
`options` when `promisified` will be unioned with `undefined`, not
optional (meaning you can't just leave it off, you'd have to
actually pass `undefined` as the value if you want to use it).

microsoft/TypeScript#13570
microsoft/TypeScript#13195

Author: tlancina

.gitignore

@@ -1,3 +1,5 @@
+*.swp
 dist
 node_modules
 .DS_Store
+.vscode

src/utils/unzip.ts

@@ -1,11 +1,11 @@
 import { Readable } from 'stream';
 import { promisify } from 'util';
-import { Entry, Options, ZipFile } from 'yauzl';
+import { Entry, Options, ZipFile, ZipFileOptions } from 'yauzl';
 
-// Override so promisify typing correctly infers params
-export type YauzlOpenReadStream = (entry: Entry, callback?: (err: Error, stream: Readable) => void) => Promise<Readable>;
-type YauzlOpen = (path: string, options: Options, callback?: (err: Error, zipfile: ZipFile) => void) => void;
-type UnzipOnEntry = (entry: Entry, zipfile: ZipFile, openReadStream: YauzlOpenReadStream) => void;
+// Specify which of possible overloads is being promisified
+type YauzlOpenReadStream = (entry: Entry, options?: ZipFileOptions, callback?: (err: Error, stream: Readable) => void) => void;
+type YauzlOpen = (path: string, options?: Options, callback?: (err: Error, zipfile: ZipFile) => void) => void;
+type UnzipOnEntry = (entry: Entry, zipfile: ZipFile, openReadStream: (arg1: Entry, arg2?: ZipFileOptions) => Promise<Readable>) => void;
 
 export async function unzip(srcPath: string, onEntry: UnzipOnEntry) {
   const yauzl = await import('yauzl');