feat: add signal exit (#65)

Author: hugomrdias

README.md

@@ -159,18 +159,7 @@ Returns a boolean or throws on error.
 
 ## Graceful exit
 
-`proper-lockfile` automatically remove locks if the process exists. Though, `SIGINT` and `SIGTERM` signals
-are handled differently by `nodejs` in the sense that they do not fire a `exit` event on the `process`.
-To avoid this common issue that `CLI` developers have, please do the following:
-
-
-```js
-// Map SIGINT & SIGTERM to process exit
-// so that lockfile removes the lockfile automatically
-process
-.once('SIGINT', () => process.exit(1))
-.once('SIGTERM', () => process.exit(1));
-```
+`proper-lockfile` automatically remove locks if the process exists.
 
 
 ## Tests

lib/lockfile.js

@@ -3,6 +3,7 @@
 const path = require('path');
 const fs = require('graceful-fs');
 const retry = require('retry');
+const onExit = require('signal-exit');
 
 const locks = {};
 
@@ -292,7 +293,7 @@ function getLocks() {
 
 // Remove acquired locks on exit
 /* istanbul ignore next */
-process.on('exit', () => {
+onExit(() => {
     for (const file in locks) {
         try { locks[file].options.fs.rmdirSync(getLockFile(file)); } catch (e) { /* Empty */ }
     }