added unit testing, and started implementing unit tests...phew

node_modules/assertion-error/index.d.ts

@@ -0,0 +1,11 @@
+type AssertionError<T = {}> = Error & T & {
+    showDiff: boolean;
+};
+
+interface AssertionErrorConstructor {
+    new<T = {}>(message: string, props?: T, ssf?: Function): AssertionError<T>;
+}
+
+declare const AssertionError: AssertionErrorConstructor;
+
+export = AssertionError;