DnsConfigService and a posix implementation

net/dns/dns_config_service_posix_unittest.cc

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <resolv.h>  // POSIX only
+
+#include "base/bind.h"
+#include "base/message_loop.h"
+#include "base/message_loop_proxy.h"
+#include "base/synchronization/waitable_event.h"
+#include "base/threading/thread.h"
+#include "net/base/ip_endpoint.h"
+#include "net/dns/dns_config_service.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace net {
+
+namespace {
+
+// strategy similar to testing FilePathWatcher
+
+// A mock DnsConfigService::Delegate for testing.
+// This is RefCountedThreadSafe to make sure it's cleaned up.
+struct TestObserver : public DnsConfigService::Observer,
+                      public base::RefCountedThreadSafe<TestObserver> {
+  explicit TestObserver(base::WaitableEvent* completion)
+    : completion(completion) {}
+  virtual ~TestObserver() {}
+
+  void StartWatch() {
+    service.reset(DnsConfigService::CreateSystemService());
+    service->AddObserver(this);
+  }
+
+  virtual void OnConfigChanged(const DnsConfig& new_config) OVERRIDE {
+    config = new_config;
+    completion->Signal();
+    // we must destroy the service on the same thread that called Watch
+    delete service.release();
+  }
+
+  DnsConfig config;
+  scoped_ptr<DnsConfigService> service;
+  base::WaitableEvent* completion;
+
+  DISALLOW_COPY_AND_ASSIGN(TestObserver);
+};
+
+
+// run DnsConfigService::Watch on the separate |service_thread_|
+class DnsConfigServiceTest : public testing::Test {
+ public:
+  DnsConfigServiceTest()
+    : completion_(false, false),
+      delegate_(new TestObserver(&completion_)),
+      service_thread_("DnsConfigServiceTest") {}
+
+  virtual ~DnsConfigServiceTest() {}
+
+ protected:
+  virtual void SetUp() OVERRIDE {
+    // Create a separate thread on which we call Watch and the Delegate methods
+    // TestDelegate will make it quit in OnConfigChanged
+    base::Thread::Options options(MessageLoop::TYPE_IO, 0);
+    ASSERT_TRUE(service_thread_.StartWithOptions(options));
+  }
+
+  virtual void TearDown() OVERRIDE {
+    service_thread_.Stop();
+  }
+
+  void StartWatch() {
+    completion_.Reset();  // is this needed?
+    service_thread_.message_loop()->PostTask(
+        FROM_HERE,
+        base::Bind(&TestObserver::StartWatch, delegate_.get()));
+  }
+
+  void CheckConfig(const struct __res_state &res) {
+    const DnsConfig& config = delegate_->config;
+    EXPECT_EQ(config.ndots, static_cast<int>(res.ndots));
+    EXPECT_EQ(config.edns0, res.options & RES_USE_EDNS0);
+    EXPECT_EQ(config.rotate, res.options & RES_ROTATE);
+    EXPECT_EQ(config.timeout, res.retrans);
+    EXPECT_EQ(config.attempts, res.retry);
+    // compare nameservers
+    ASSERT_EQ(config.nameservers.size(), static_cast<size_t>(res.nscount));
+    for (int i = 0; i < res.nscount; ++i) {
+      IPEndPoint ipe;
+      ASSERT_TRUE(ipe.FromSockAddr(
+          reinterpret_cast<const struct sockaddr*>(&res.nsaddr_list[i]),
+          sizeof res.nsaddr_list[i]));
+      EXPECT_EQ(config.nameservers[i], ipe);
+    }
+    // compare search
+    ASSERT_TRUE(res.dnsrch[config.search.size()] == NULL);
+    for (unsigned i = 0; i < config.search.size(); ++i) {
+      EXPECT_EQ(config.search[i], res.dnsrch[i]);
+    }
+  }
+
+  bool WaitForConfig() WARN_UNUSED_RESULT {
+    return completion_.Wait();  // TODO(szym): add timeout?
+  }
+
+ private:
+  base::WaitableEvent completion_;
+  scoped_refptr<TestObserver> delegate_;
+  base::Thread service_thread_;
+};
+
+TEST_F(DnsConfigServiceTest, VerifyWithResInit) {
+  StartWatch();
+  // NOTE: res_init() initializes __res_state.retry (DnsConfig::attempts) to 4
+  // while res_ninit() initializes it to 2, so we can't mix them in this test.
+  struct __res_state res;
+  ASSERT_EQ(res_ninit(&res), 0);

[cbentzel, 2011/08/05 19:11:39]

This seems flaky and won't get code coverage of regression cases well.

One thought is to isolate out the function which does __res_state to DNSConfig
translation to make sure that's caught.

To test the overall system, I'd suggest being able to overload the file location
name [so not /etc/resolv.conf] and add a function pointer or callback so
res_ninit isn't called, but some unit-test specific thing which generates a
predefined __res_state structure.

[szym, 2011/08/15 14:27:42]

Done.

+
+  ASSERT_TRUE(res.options & RES_INIT);
+  ASSERT_TRUE(WaitForConfig());
+  CheckConfig(res);
+}
+
+// TODO(szym) do the same but touch /etc/resolv.conf
+}
+
+}  // namespace net
+