shill: Add singleton to output resolver files

Output a file that can be linked to "resolv.conf" from the contents
of an ipconfig file.

BUG=chromium-os:17278
TEST=New unittest

Change-Id: Ic537dda6f1cb337d631bc75a3aaa835312ce8c01
Reviewed-on: http://gerrit.chromium.org/gerrit/5399
Reviewed-by: Paul Stewart <pstew@chromium.org>
Tested-by: Paul Stewart <pstew@chromium.org>
diff --git a/resolver_unittest.cc b/resolver_unittest.cc
new file mode 100644
index 0000000..1ef161d
--- /dev/null
+++ b/resolver_unittest.cc
@@ -0,0 +1,97 @@
+// Copyright (c) 2011 The Chromium OS 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 "shill/resolver.h"
+
+#include <base/file_util.h>
+#include <base/stl_util-inl.h>
+#include <base/stringprintf.h>
+#include <base/memory/scoped_temp_dir.h>
+#include <gtest/gtest.h>
+
+#include "shill/ipconfig.h"
+#include "shill/mock_control.h"
+
+using std::string;
+using std::vector;
+using testing::Test;
+
+namespace shill {
+
+namespace {
+const char kTestDeviceName0[] = "netdev0";
+const char kNameServer0[] = "8.8.8.8";
+const char kNameServer1[] = "8.8.9.9";
+const char kSearchDomain0[] = "chromium.org";
+const char kSearchDomain1[] = "google.com";
+const char kExpectedOutput[] =
+  "nameserver 8.8.8.8\n"
+  "nameserver 8.8.9.9\n"
+  "search chromium.org google.com\n";
+}  // namespace {}
+
+class ResolverTest : public Test {
+ public:
+  ResolverTest() : resolver_(Resolver::GetInstance()) {}
+
+  virtual void SetUp() {
+    ASSERT_TRUE(temp_dir_.CreateUniqueTempDir());
+    path_ = temp_dir_.path().Append("resolver");
+    resolver_->set_path(path_);
+  }
+
+  virtual void TearDown() {
+    resolver_->set_path(FilePath(""));  // Don't try to save the store.
+    ASSERT_TRUE(temp_dir_.Delete());
+  }
+
+ protected:
+  string ReadFile();
+
+  ScopedTempDir temp_dir_;
+  Resolver *resolver_;
+  FilePath path_;
+};
+
+string ResolverTest::ReadFile() {
+  string data;
+  EXPECT_TRUE(file_util::ReadFileToString(resolver_->path_, &data));
+  return data;
+}
+
+TEST_F(ResolverTest, NonEmpty) {
+  EXPECT_FALSE(file_util::PathExists(path_));
+  EXPECT_TRUE(resolver_->ClearDNS());
+
+  // Add DNS info from an IPConfig entry
+  MockControl control;
+  IPConfigRefPtr ipconfig(new IPConfig(&control, kTestDeviceName0));
+  IPConfig::Properties properties;
+  properties.dns_servers.push_back(kNameServer0);
+  properties.dns_servers.push_back(kNameServer1);
+  properties.domain_search.push_back(kSearchDomain0);
+  properties.domain_search.push_back(kSearchDomain1);
+  ipconfig->UpdateProperties(properties, true);
+
+  EXPECT_TRUE(resolver_->SetDNS(ipconfig));
+  EXPECT_TRUE(file_util::PathExists(path_));
+  EXPECT_EQ(kExpectedOutput, ReadFile());
+
+  EXPECT_TRUE(resolver_->ClearDNS());
+}
+
+TEST_F(ResolverTest, Empty) {
+  EXPECT_FALSE(file_util::PathExists(path_));
+
+  // Use empty ifconfig
+  MockControl control;
+  IPConfigRefPtr ipconfig(new IPConfig(&control, kTestDeviceName0));
+  IPConfig::Properties properties;
+  ipconfig->UpdateProperties(properties, true);
+
+  EXPECT_TRUE(resolver_->SetDNS(ipconfig));
+  EXPECT_FALSE(file_util::PathExists(path_));
+}
+
+}  // namespace shill