[tests] Unit tests for clock skew retry timeout

test/storage/http_expires.cpp

@@ -1,5 +1,6 @@
 #include "storage.hpp"
 
+#include <mbgl/storage/default_file_source.hpp>
 #include <mbgl/storage/online_file_source.hpp>
 #include <mbgl/util/chrono.hpp>
 #include <mbgl/util/run_loop.hpp>
@@ -33,3 +34,37 @@ TEST_F(Storage, HTTPRetryDelayOnExpiredTile) {
 
     HTTPRetryDelayOnExpiredTile.finish();
 }
+
+TEST_F(Storage, HTTPRetryOnClockSkew) {
+    SCOPED_TEST(HTTPRetryOnClockSkew)
+
+    using namespace mbgl;
+
+    util::RunLoop loop;
+    DefaultFileSource fs(":memory:", ".");
+
+    int counter = 0;
+
+    const Resource resource { Resource::Unknown, "http://127.0.0.1:3000/clockskew" };
+    std::unique_ptr<FileRequest> req1 = fs.request(resource, [&](Response res) {
+        switch (counter++) {
+        case 0: {
+            EXPECT_EQ(nullptr, res.error);
+            EXPECT_GT(SystemClock::now(), res.expires);
+        } break;
+        case 1: {
+            EXPECT_EQ(nullptr, res.error);
+
+            auto now = SystemClock::now();
+            EXPECT_LT(now + Seconds(40), res.expires) << "Expiration not interpolated to 60s";
+            EXPECT_GT(now + Seconds(80), res.expires) << "Expiration not interpolated to 60s";
+
+            loop.stop();
+        } break;
+        }
+    });
+
+    loop.run();
+
+    HTTPRetryOnClockSkew.finish();
+}

test/storage/server.js

@@ -55,6 +55,11 @@ app.get('/revalidate-same', function(req, res) {
     }
 });
 
+var expiresCounter = 0;
+app.get('/clockskew', function (req, res) {
+    res.setHeader('Expires', (new Date(2010, 1, 1, 10, ++expiresCounter, 0)).toUTCString());
+    res.status(200).send('Response');
+});
 
 app.get('/revalidate-modified', function(req, res) {
     var jan1 = new Date('jan 1 2015 utc');