Add TypeScript definition (#7)

index.d.ts

@@ -0,0 +1,37 @@
+/// <reference types="node"/>
+
+/**
+Get the name of the current operating system.
+
+By default, the name of the current operating system is returned.
+
+@param platform - Custom platform name.
+@param release - Custom release name.
+
+@example
+```
+import * as os fron 'os';
+import osName = require('os-name');
+
+// On a macOS Sierra system
+
+osName();
+//=> 'macOS Sierra'
+
+osName(os.platform(), os.release());
+//=> 'macOS Sierra'
+
+osName('darwin', '14.0.0');
+//=> 'OS X Yosemite'
+
+osName('linux', '3.13.0-24-generic');
+//=> 'Linux 3.13'
+
+osName('win32', '6.3.9600');
+//=> 'Windows 8.1'
+```
+*/
+declare function osName(): string;
+declare function osName(platform: NodeJS.Platform, release: string): string;
+
+export = osName;

index.js

@@ -3,7 +3,7 @@ const os = require('os');
 const macosRelease = require('macos-release');
 const winRelease = require('windows-release');
 
-module.exports = (platform, release) => {
+const osName = (platform, release) => {
 	if (!platform && release) {
 		throw new Error('You can\'t specify a `release` without specifying `platform`');
 	}
@@ -42,3 +42,5 @@ module.exports = (platform, release) => {
 
 	return platform;
 };
+
+module.exports = osName;

index.test-d.ts

@@ -0,0 +1,9 @@
+import {expectType} from 'tsd';
+import * as os from 'os';
+import osName = require('.');
+
+expectType<string>(osName());
+expectType<string>(osName(os.platform(), os.release()));
+expectType<string>(osName('darwin', '14.0.0'));
+expectType<string>(osName('linux', '3.13.0-24-generic'));
+expectType<string>(osName('win32', '6.3.9600'));

package.json

@@ -13,10 +13,11 @@
 		"node": ">=6"
 	},
 	"scripts": {
-		"test": "xo && ava"
+		"test": "xo && ava && tsd"
 	},
 	"files": [
-		"index.js"
+		"index.js",
+		"index.d.ts"
 	],
 	"keywords": [
 		"os",
@@ -32,11 +33,13 @@
 		"linux"
 	],
 	"dependencies": {
-		"macos-release": "^2.0.0",
+		"macos-release": "^2.2.0",
 		"windows-release": "^3.1.0"
 	},
 	"devDependencies": {
-		"ava": "^0.25.0",
-		"xo": "^0.23.0"
+		"@types/node": "^11.13.0",
+		"ava": "^1.4.1",
+		"tsd": "^0.7.2",
+		"xo": "^0.24.0"
 	}
 }