refactor for cross platform use

__tests__/github.test.ts

@@ -0,0 +1,30 @@
+//import * as assert from "assert";
+//const assert = require('assert');
+import * as assert from 'assert';
+import { mimeOrDefault, asset } from '../src/github';
+
+describe('github', () => {
+	describe('mimeOrDefault', () => {
+		it('returns a specific mime for common path', async () => {
+			assert.equal(mimeOrDefault('foo.tar.gz'), 'application/gzip')
+		});
+		it('returns default mime for uncommon path', async () => {
+			assert.equal(mimeOrDefault('foo.uncommon'), 'application/octet-stream')
+		});
+	});
+
+	describe('asset', () => {
+		it('derives asset info from a path', async () => {
+			const {
+				name,
+				mime,
+				size,
+				file
+			} = asset('tests/data/foo/bar.txt');
+			assert.equal(name, 'bar.txt');
+			assert.equal(mime, 'text/plain');
+			assert.equal(size, 10);
+			assert.equal(file.toString(), 'release me')
+		});
+	})
+});