From 752bc6f8360258966b5501c78b8bc1f5ff759827 Mon Sep 17 00:00:00 2001
From: Luke Childs <lukechilds123@gmail.com>
Date: Fri, 23 Dec 2016 11:33:31 +0700
Subject: [PATCH] Test expired.in returns negative ms for stale cache

---
 test/expired.in.js | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/test/expired.in.js b/test/expired.in.js
index 9be4ed3..9d7545f 100644
--- a/test/expired.in.js
+++ b/test/expired.in.js
@@ -1,5 +1,6 @@
 import test from 'ava';
 import tk from 'timekeeper';
+import subSeconds from 'date-fns/sub_seconds';
 import expired from '../';
 
 test('expired.in is a function', t => {
@@ -32,3 +33,18 @@ test('expired.in returns zero ms for instantly stale cache', t => {
 	t.is(expired.in(headers), 0);
 	tk.reset();
 });
+
+test('expired.in returns negative ms for stale cache', t => {
+	const date = new Date().toUTCString();
+	const dateOffset = 600;
+	const maxAge = 300;
+	const headers = {
+		date: subSeconds(date, dateOffset).toUTCString(),
+		age: 0,
+		'cache-control': `public, max-age=${maxAge}`
+	};
+
+	tk.freeze(date);
+	t.is(expired.in(headers), (maxAge - dateOffset) * 1000);
+	tk.reset();
+});