diff --git a/proxy_resolver_unittest.cc b/proxy_resolver_unittest.cc
new file mode 100644
index 0000000..070b361
--- /dev/null
+++ b/proxy_resolver_unittest.cc
@@ -0,0 +1,92 @@
+//
+// Copyright (C) 2017 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include "update_engine/proxy_resolver.h"
+
+#include <deque>
+#include <string>
+
+#include <gtest/gtest.h>
+
+#include <base/bind.h>
+#include <brillo/bind_lambda.h>
+#include <brillo/message_loops/fake_message_loop.h>
+
+using std::deque;
+using std::string;
+
+namespace chromeos_update_engine {
+
+class ProxyResolverTest : public ::testing::Test {
+ protected:
+  virtual ~ProxyResolverTest() = default;
+
+  void SetUp() override { loop_.SetAsCurrent(); }
+
+  void TearDown() override { EXPECT_FALSE(loop_.PendingTasks()); }
+
+  brillo::FakeMessageLoop loop_{nullptr};
+  DirectProxyResolver resolver_;
+};
+
+TEST_F(ProxyResolverTest, DirectProxyResolverCallbackTest) {
+  bool called = false;
+  deque<string> callback_proxies;
+  auto callback = base::Bind(
+      [](bool* called,
+         deque<string>* callback_proxies,
+         const deque<string>& proxies) {
+        *called = true;
+        *callback_proxies = proxies;
+      },
+      &called,
+      &callback_proxies);
+
+  EXPECT_NE(kProxyRequestIdNull,
+            resolver_.GetProxiesForUrl("http://foo", callback));
+  // Check the callback is not called until the message loop runs.
+  EXPECT_FALSE(called);
+  loop_.Run();
+  EXPECT_TRUE(called);
+  EXPECT_EQ(kNoProxy, callback_proxies.front());
+}
+
+TEST_F(ProxyResolverTest, DirectProxyResolverCancelCallbackTest) {
+  bool called = false;
+  auto callback = base::Bind(
+      [](bool* called, const deque<string>& proxies) { *called = true; },
+      &called);
+
+  ProxyRequestId request = resolver_.GetProxiesForUrl("http://foo", callback);
+  EXPECT_FALSE(called);
+  EXPECT_TRUE(resolver_.CancelProxyRequest(request));
+  loop_.Run();
+  EXPECT_FALSE(called);
+}
+
+TEST_F(ProxyResolverTest, DirectProxyResolverSimultaneousCallbacksTest) {
+  int called = 0;
+  auto callback = base::Bind(
+      [](int* called, const deque<string>& proxies) { (*called)++; }, &called);
+
+  resolver_.GetProxiesForUrl("http://foo", callback);
+  resolver_.GetProxiesForUrl("http://bar", callback);
+  EXPECT_EQ(0, called);
+  loop_.Run();
+  EXPECT_EQ(2, called);
+}
+
+}  // namespace chromeos_update_engine