Feature/jest2 (#322)

* Adding more tests
* adding jest
* fixing tests
* fixing linting
* removing 1 slash less
* fixing more tests
* fixing last test
* more last fixes

test/src/github.ts

@@ -9,7 +9,7 @@ export interface ErrorAnnotation {
 export namespace Github {
   export function createError(message: string, error: ErrorAnnotation = {}): void {
     const data = Object.entries(error)
-      .filter(([key, value]) => value !== undefined)
+      .filter(([, value]) => value !== undefined)
       .map(([key, value]) => `${key}=${value}`)
       .join(",");