update_engine: Use constants for the channels

Use constants for the channels and replace all strings in the
repository.

BUG=None
TEST=update_engine unit tests

Change-Id: Ibb84c6deefec1fab6181f150f358b99e8b8a2d8a
Reviewed-on: https://chromium-review.googlesource.com/c/aosp/platform/system/update_engine/+/4359654
Tested-by: Victor-Gabriel Savu <vsavu@google.com>
Commit-Queue: Victor-Gabriel Savu <vsavu@google.com>
Reviewed-by: Jae Hoon Kim <kimjae@chromium.org>

10 files changed, 108 insertions, 101 deletions

diff --git a/common/constants.h b/common/constants.h
index c3dac63f..2a3cdcb6 100644
--- a/common/constants.h
+++ b/common/constants.h
@@ -235,6 +235,14 @@ const int kSHA256Size = 32;
 // Limit on the number of consecutive updates.
 const int64_t kConsecutiveUpdateLimit = 3;
 
+// Channel constants.
+constexpr const char kCanaryChannel[] = "canary-channel";
+constexpr const char kDevChannel[] = "dev-channel";
+constexpr const char kBetaChannel[] = "beta-channel";
+constexpr const char kStableChannel[] = "stable-channel";
+constexpr const char kLtcChannel[] = "ltc-channel";
+constexpr const char kLtsChannel[] = "lts-channel";
+
 }  // namespace chromeos_update_engine
 
 #endif  // UPDATE_ENGINE_COMMON_CONSTANTS_H_
diff --git a/cros/common_service_unittest.cc b/cros/common_service_unittest.cc
index 70a443a8..a5cb81a9 100644
--- a/cros/common_service_unittest.cc
+++ b/cros/common_service_unittest.cc
@@ -129,9 +129,9 @@ TEST_F(UpdateEngineServiceTest, SetChannelWithNoPolicy) {
   EXPECT_CALL(*mock_update_attempter_, RefreshDevicePolicy());
   // If SetTargetChannel is called it means the policy check passed.
   EXPECT_CALL(*FakeSystemState::Get()->mock_request_params(),
-              SetTargetChannel("stable-channel", true, _))
+              SetTargetChannel(kStableChannel, true, _))
       .WillOnce(Return(true));
-  EXPECT_TRUE(common_service_.SetChannel(&error_, "stable-channel", true));
+  EXPECT_TRUE(common_service_.SetChannel(&error_, kStableChannel, true));
   ASSERT_EQ(nullptr, error_);
 }
 
@@ -142,10 +142,10 @@ TEST_F(UpdateEngineServiceTest, SetChannelWithDelegatedPolicy) {
   EXPECT_CALL(mock_device_policy, GetReleaseChannelDelegated(_))
       .WillOnce(DoAll(SetArgPointee<0>(true), Return(true)));
   EXPECT_CALL(*FakeSystemState::Get()->mock_request_params(),
-              SetTargetChannel("beta-channel", true, _))
+              SetTargetChannel(kBetaChannel, true, _))
       .WillOnce(Return(true));
 
-  EXPECT_TRUE(common_service_.SetChannel(&error_, "beta-channel", true));
+  EXPECT_TRUE(common_service_.SetChannel(&error_, kBetaChannel, true));
   ASSERT_EQ(nullptr, error_);
 }
 
@@ -167,7 +167,7 @@ TEST_F(UpdateEngineServiceTest, SetChannelWithInvalidChannel) {
 TEST_F(UpdateEngineServiceTest, SetChannelWithCommercialChannelLts) {
   EXPECT_CALL(*mock_update_attempter_, RefreshDevicePolicy());
 
-  EXPECT_FALSE(common_service_.SetChannel(&error_, "lts-channel", true));
+  EXPECT_FALSE(common_service_.SetChannel(&error_, kLtsChannel, true));
   ASSERT_NE(nullptr, error_);
   EXPECT_TRUE(error_->HasError(UpdateEngineService::kErrorDomain,
                                UpdateEngineService::kErrorFailed));
@@ -177,7 +177,7 @@ TEST_F(UpdateEngineServiceTest, SetChannelWithCommercialChannelLts) {
 TEST_F(UpdateEngineServiceTest, SetChannelWithCommercialChannelLtc) {
   EXPECT_CALL(*mock_update_attempter_, RefreshDevicePolicy());
 
-  EXPECT_FALSE(common_service_.SetChannel(&error_, "ltc-channel", true));
+  EXPECT_FALSE(common_service_.SetChannel(&error_, kLtcChannel, true));
   ASSERT_NE(nullptr, error_);
   EXPECT_TRUE(error_->HasError(UpdateEngineService::kErrorDomain,
                                UpdateEngineService::kErrorFailed));
diff --git a/cros/image_properties_chromeos.cc b/cros/image_properties_chromeos.cc
index 2e159f09..5e06242c 100644
--- a/cros/image_properties_chromeos.cc
+++ b/cros/image_properties_chromeos.cc
@@ -94,7 +94,7 @@ ImageProperties LoadImageProperties() {
   brillo::KeyValueStore lsb_release;
   LoadLsbRelease(LsbReleaseSource::kSystem, &lsb_release);
   result.current_channel = GetStringWithDefault(
-      lsb_release, kLsbReleaseUpdateChannelKey, "stable-channel");
+      lsb_release, kLsbReleaseUpdateChannelKey, kStableChannel);
 
   // In dev-mode and unofficial build we can override the image properties set
   // in the system image with the ones from the stateful partition, except the
@@ -134,7 +134,7 @@ MutableImageProperties LoadMutableImageProperties() {
   LoadLsbRelease(LsbReleaseSource::kSystem, &lsb_release);
   LoadLsbRelease(LsbReleaseSource::kStateful, &lsb_release);
   result.target_channel = GetStringWithDefault(
-      lsb_release, kLsbReleaseUpdateChannelKey, "stable-channel");
+      lsb_release, kLsbReleaseUpdateChannelKey, kStableChannel);
   if (!lsb_release.GetBoolean(kLsbReleaseIsPowerwashAllowedKey,
                               &result.is_powerwash_allowed))
     result.is_powerwash_allowed = false;
diff --git a/cros/image_properties_chromeos_unittest.cc b/cros/image_properties_chromeos_unittest.cc
index 497554e2..4f91d29f 100644
--- a/cros/image_properties_chromeos_unittest.cc
+++ b/cros/image_properties_chromeos_unittest.cc
@@ -64,7 +64,7 @@ TEST_F(ImagePropertiesTest, SimpleTest) {
   EXPECT_EQ("arm-generic", props.board);
   EXPECT_EQ("{87efface-864d-49a5-9bb3-4b050a7c227a}", props.product_id);
   EXPECT_EQ("0.2.2.3", props.version);
-  EXPECT_EQ("dev-channel", props.current_channel);
+  EXPECT_EQ(kDevChannel, props.current_channel);
   EXPECT_EQ("http://www.google.com", props.omaha_url);
 }
 
@@ -104,10 +104,10 @@ TEST_F(ImagePropertiesTest, OverrideTest) {
       "CHROMEOS_AUSERVER=https://www.google.com"));
   ImageProperties props = LoadImageProperties();
   EXPECT_EQ("x86-generic", props.board);
-  EXPECT_EQ("dev-channel", props.current_channel);
+  EXPECT_EQ(kDevChannel, props.current_channel);
   EXPECT_EQ("https://www.google.com", props.omaha_url);
   MutableImageProperties mutable_props = LoadMutableImageProperties();
-  EXPECT_EQ("beta-channel", mutable_props.target_channel);
+  EXPECT_EQ(kBetaChannel, mutable_props.target_channel);
 }
 
 TEST_F(ImagePropertiesTest, OverrideLockDownTest) {
@@ -125,10 +125,10 @@ TEST_F(ImagePropertiesTest, OverrideLockDownTest) {
   SetLockDown(true);
   ImageProperties props = LoadImageProperties();
   EXPECT_EQ("arm-generic", props.board);
-  EXPECT_EQ("dev-channel", props.current_channel);
+  EXPECT_EQ(kDevChannel, props.current_channel);
   EXPECT_EQ("https://www.google.com", props.omaha_url);
   MutableImageProperties mutable_props = LoadMutableImageProperties();
-  EXPECT_EQ("stable-channel", mutable_props.target_channel);
+  EXPECT_EQ(kStableChannel, mutable_props.target_channel);
 }
 
 TEST_F(ImagePropertiesTest, BoardAppIdUsedForNonCanaryChannelTest) {
@@ -139,7 +139,7 @@ TEST_F(ImagePropertiesTest, BoardAppIdUsedForNonCanaryChannelTest) {
                       "CHROMEOS_CANARY_APPID=c\n"
                       "CHROMEOS_RELEASE_TRACK=stable-channel\n"));
   ImageProperties props = LoadImageProperties();
-  EXPECT_EQ("stable-channel", props.current_channel);
+  EXPECT_EQ(kStableChannel, props.current_channel);
   EXPECT_EQ("b", props.product_id);
 }
 
@@ -151,7 +151,7 @@ TEST_F(ImagePropertiesTest, CanaryAppIdUsedForCanaryChannelTest) {
                       "CHROMEOS_CANARY_APPID=c\n"
                       "CHROMEOS_RELEASE_TRACK=canary-channel\n"));
   ImageProperties props = LoadImageProperties();
-  EXPECT_EQ("canary-channel", props.current_channel);
+  EXPECT_EQ(kCanaryChannel, props.current_channel);
   EXPECT_EQ("c", props.canary_product_id);
 }
 
@@ -162,7 +162,7 @@ TEST_F(ImagePropertiesTest, ReleaseAppIdUsedAsDefaultTest) {
                       "CHROMEOS_CANARY_APPID=c\n"
                       "CHROMEOS_RELEASE_TRACK=stable-channel\n"));
   ImageProperties props = LoadImageProperties();
-  EXPECT_EQ("stable-channel", props.current_channel);
+  EXPECT_EQ(kStableChannel, props.current_channel);
   EXPECT_EQ("r", props.product_id);
 }
 
diff --git a/cros/omaha_request_action_unittest.cc b/cros/omaha_request_action_unittest.cc
index b325233d..c57066b1 100644
--- a/cros/omaha_request_action_unittest.cc
+++ b/cros/omaha_request_action_unittest.cc
@@ -2436,9 +2436,8 @@ TEST_F(OmahaRequestActionTest, TestChangingToMoreStableChannel) {
   request_params_.set_app_id("{22222222-2222-2222-2222-222222222222}");
   request_params_.set_app_version("1.2.3.4");
   request_params_.set_product_components("o.bundle=1");
-  request_params_.set_current_channel("canary-channel");
-  EXPECT_TRUE(
-      request_params_.SetTargetChannel("stable-channel", true, nullptr));
+  request_params_.set_current_channel(kCanaryChannel);
+  EXPECT_TRUE(request_params_.SetTargetChannel(kStableChannel, true, nullptr));
   request_params_.UpdateDownloadChannel();
   EXPECT_TRUE(request_params_.ShouldPowerwash());
 
@@ -2466,9 +2465,8 @@ TEST_F(OmahaRequestActionTest, TestChangingToLessStableChannel) {
   request_params_.set_app_id("{11111111-1111-1111-1111-111111111111}");
   request_params_.set_app_version("5.6.7.8");
   request_params_.set_product_components("o.bundle=1");
-  request_params_.set_current_channel("stable-channel");
-  EXPECT_TRUE(
-      request_params_.SetTargetChannel("canary-channel", false, nullptr));
+  request_params_.set_current_channel(kStableChannel);
+  EXPECT_TRUE(request_params_.SetTargetChannel(kCanaryChannel, false, nullptr));
   request_params_.UpdateDownloadChannel();
   EXPECT_FALSE(request_params_.ShouldPowerwash());
 
diff --git a/cros/omaha_request_params.cc b/cros/omaha_request_params.cc
index c829a934..4bf16f32 100644
--- a/cros/omaha_request_params.cc
+++ b/cros/omaha_request_params.cc
@@ -50,12 +50,12 @@ namespace chromeos_update_engine {
 namespace {
 const char* kChannelsByStability[] = {
     // This list has to be sorted from least stable to most stable channel.
-    "canary-channel",
-    "dev-channel",
-    "beta-channel",
-    "stable-channel",
-    "ltc-channel",
-    "lts-channel",
+    kCanaryChannel,
+    kDevChannel,
+    kBetaChannel,
+    kStableChannel,
+    kLtcChannel,
+    kLtsChannel,
 };
 }  // namespace
 
@@ -77,7 +77,7 @@ bool OmahaRequestParams::Init(const string& app_version,
 
   // Validation check the channel names.
   if (!IsValidChannel(image_props_.current_channel))
-    image_props_.current_channel = "stable-channel";
+    image_props_.current_channel = kStableChannel;
   if (!IsValidChannel(mutable_image_props_.target_channel))
     mutable_image_props_.target_channel = image_props_.current_channel;
 
@@ -86,7 +86,7 @@ bool OmahaRequestParams::Init(const string& app_version,
   if (IsCommercialChannel(mutable_image_props_.target_channel)) {
     LOG(WARNING) << "Commercial channel " << mutable_image_props_.target_channel
                  << " can only be set by policy. Defaulting to stable-channel";
-    mutable_image_props_.target_channel = "stable-channel";
+    mutable_image_props_.target_channel = kStableChannel;
   }
   UpdateDownloadChannel();
 
@@ -271,7 +271,7 @@ bool OmahaRequestParams::IsValidChannel(const string& channel,
 
 // static
 bool OmahaRequestParams::IsCommercialChannel(const string& channel) {
-  return channel == "ltc-channel" || channel == "lts-channel";
+  return channel == kLtcChannel || channel == kLtsChannel;
 }
 
 void OmahaRequestParams::set_root(const string& root) {
@@ -306,8 +306,8 @@ bool OmahaRequestParams::ShouldPowerwash() const {
 }
 
 string OmahaRequestParams::GetAppId() const {
-  return download_channel_ == "canary-channel" ? image_props_.canary_product_id
-                                               : image_props_.product_id;
+  return download_channel_ == kCanaryChannel ? image_props_.canary_product_id
+                                             : image_props_.product_id;
 }
 
 string OmahaRequestParams::GetDlcAppId(const std::string& dlc_id) const {
diff --git a/cros/omaha_request_params_unittest.cc b/cros/omaha_request_params_unittest.cc
index 51373df5..be318fd8 100644
--- a/cros/omaha_request_params_unittest.cc
+++ b/cros/omaha_request_params_unittest.cc
@@ -73,7 +73,7 @@ string GetMachineType() {
 TEST_F(OmahaRequestParamsTest, MissingChannelTest) {
   EXPECT_TRUE(params_.Init("", "", {}));
   // By default, if no channel is set, we should track the stable-channel.
-  EXPECT_EQ("stable-channel", params_.target_channel());
+  EXPECT_EQ(kStableChannel, params_.target_channel());
 }
 
 TEST_F(OmahaRequestParamsTest, ForceVersionTest) {
@@ -109,12 +109,12 @@ TEST_F(OmahaRequestParamsTest, SetTargetChannelTest) {
     OmahaRequestParams params;
     params.set_root(tempdir_.GetPath().value());
     EXPECT_TRUE(params.Init("", "", {}));
-    EXPECT_TRUE(params.SetTargetChannel("canary-channel", false, nullptr));
+    EXPECT_TRUE(params.SetTargetChannel(kCanaryChannel, false, nullptr));
     EXPECT_FALSE(params.mutable_image_props_.is_powerwash_allowed);
   }
   params_.set_root(tempdir_.GetPath().value());
   EXPECT_TRUE(params_.Init("", "", {}));
-  EXPECT_EQ("canary-channel", params_.target_channel());
+  EXPECT_EQ(kCanaryChannel, params_.target_channel());
   EXPECT_FALSE(params_.mutable_image_props_.is_powerwash_allowed);
 }
 
@@ -123,11 +123,11 @@ TEST_F(OmahaRequestParamsTest, SetTargetCommercialChannelTest) {
     OmahaRequestParams params;
     params.set_root(tempdir_.GetPath().value());
     EXPECT_TRUE(params.Init("", "", {}));
-    EXPECT_TRUE(params.SetTargetChannel("ltc-channel", false, nullptr));
+    EXPECT_TRUE(params.SetTargetChannel(kLtcChannel, false, nullptr));
   }
   params_.set_root(tempdir_.GetPath().value());
   EXPECT_TRUE(params_.Init("", "", {}));
-  EXPECT_EQ("stable-channel", params_.target_channel());
+  EXPECT_EQ(kStableChannel, params_.target_channel());
 }
 
 TEST_F(OmahaRequestParamsTest, SetCommercialChannelUsingParamTest) {
@@ -135,11 +135,11 @@ TEST_F(OmahaRequestParamsTest, SetCommercialChannelUsingParamTest) {
     OmahaRequestParams params;
     params.set_root(tempdir_.GetPath().value());
     EXPECT_TRUE(params.Init("", "", {}));
-    EXPECT_TRUE(params.SetTargetChannel("stable-channel", false, nullptr));
+    EXPECT_TRUE(params.SetTargetChannel(kStableChannel, false, nullptr));
   }
   params_.set_root(tempdir_.GetPath().value());
-  EXPECT_TRUE(params_.Init("", "", {.target_channel = "ltc-channel"}));
-  EXPECT_EQ("ltc-channel", params_.target_channel());
+  EXPECT_TRUE(params_.Init("", "", {.target_channel = kLtcChannel}));
+  EXPECT_EQ(kLtcChannel, params_.target_channel());
 }
 
 TEST_F(OmahaRequestParamsTest, SetIsPowerwashAllowedTest) {
@@ -147,12 +147,12 @@ TEST_F(OmahaRequestParamsTest, SetIsPowerwashAllowedTest) {
     OmahaRequestParams params;
     params.set_root(tempdir_.GetPath().value());
     EXPECT_TRUE(params.Init("", "", {}));
-    EXPECT_TRUE(params.SetTargetChannel("canary-channel", true, nullptr));
+    EXPECT_TRUE(params.SetTargetChannel(kCanaryChannel, true, nullptr));
     EXPECT_TRUE(params.mutable_image_props_.is_powerwash_allowed);
   }
   params_.set_root(tempdir_.GetPath().value());
   EXPECT_TRUE(params_.Init("", "", {}));
-  EXPECT_EQ("canary-channel", params_.target_channel());
+  EXPECT_EQ(kCanaryChannel, params_.target_channel());
   EXPECT_TRUE(params_.mutable_image_props_.is_powerwash_allowed);
 }
 
@@ -167,22 +167,22 @@ TEST_F(OmahaRequestParamsTest, SetTargetChannelInvalidTest) {
     EXPECT_FALSE(
         params.SetTargetChannel("dogfood-channel", true, &error_message));
     // The error message should include a message about the valid channels.
-    EXPECT_NE(string::npos, error_message.find("stable-channel"));
+    EXPECT_NE(string::npos, error_message.find(kStableChannel));
     EXPECT_FALSE(params.mutable_image_props_.is_powerwash_allowed);
   }
   params_.set_root(tempdir_.GetPath().value());
   EXPECT_TRUE(params_.Init("", "", {}));
-  EXPECT_EQ("stable-channel", params_.target_channel());
+  EXPECT_EQ(kStableChannel, params_.target_channel());
   EXPECT_FALSE(params_.mutable_image_props_.is_powerwash_allowed);
 }
 
 TEST_F(OmahaRequestParamsTest, IsValidChannelTest) {
-  EXPECT_TRUE(params_.IsValidChannel("canary-channel"));
-  EXPECT_TRUE(params_.IsValidChannel("stable-channel"));
-  EXPECT_TRUE(params_.IsValidChannel("beta-channel"));
-  EXPECT_TRUE(params_.IsValidChannel("dev-channel"));
-  EXPECT_TRUE(params_.IsValidChannel("ltc-channel"));
-  EXPECT_TRUE(params_.IsValidChannel("lts-channel"));
+  EXPECT_TRUE(params_.IsValidChannel(kCanaryChannel));
+  EXPECT_TRUE(params_.IsValidChannel(kStableChannel));
+  EXPECT_TRUE(params_.IsValidChannel(kBetaChannel));
+  EXPECT_TRUE(params_.IsValidChannel(kDevChannel));
+  EXPECT_TRUE(params_.IsValidChannel(kLtcChannel));
+  EXPECT_TRUE(params_.IsValidChannel(kLtsChannel));
   EXPECT_FALSE(params_.IsValidChannel("testimage-channel"));
   EXPECT_FALSE(params_.IsValidChannel("dogfood-channel"));
   EXPECT_FALSE(params_.IsValidChannel("some-channel"));
@@ -195,51 +195,51 @@ TEST_F(OmahaRequestParamsTest, IsValidChannelTest) {
 }
 
 TEST_F(OmahaRequestParamsTest, SetTargetChannelWorks) {
-  params_.set_target_channel("dev-channel");
-  EXPECT_EQ("dev-channel", params_.target_channel());
+  params_.set_target_channel(kDevChannel);
+  EXPECT_EQ(kDevChannel, params_.target_channel());
 
   // When an invalid value is set, it should be ignored.
   EXPECT_FALSE(params_.SetTargetChannel("invalid-channel", false, nullptr));
-  EXPECT_EQ("dev-channel", params_.target_channel());
+  EXPECT_EQ(kDevChannel, params_.target_channel());
 
   // When set to a valid value, it should take effect.
-  EXPECT_TRUE(params_.SetTargetChannel("beta-channel", true, nullptr));
-  EXPECT_EQ("beta-channel", params_.target_channel());
+  EXPECT_TRUE(params_.SetTargetChannel(kBetaChannel, true, nullptr));
+  EXPECT_EQ(kBetaChannel, params_.target_channel());
 
   // When set to the same value, it should be idempotent.
-  EXPECT_TRUE(params_.SetTargetChannel("beta-channel", true, nullptr));
-  EXPECT_EQ("beta-channel", params_.target_channel());
+  EXPECT_TRUE(params_.SetTargetChannel(kBetaChannel, true, nullptr));
+  EXPECT_EQ(kBetaChannel, params_.target_channel());
 
   // When set to a valid value while a change is already pending, it should
   // succeed.
-  EXPECT_TRUE(params_.SetTargetChannel("stable-channel", true, nullptr));
-  EXPECT_EQ("stable-channel", params_.target_channel());
+  EXPECT_TRUE(params_.SetTargetChannel(kStableChannel, true, nullptr));
+  EXPECT_EQ(kStableChannel, params_.target_channel());
 
   // Set a different channel in mutable_image_props_.
-  params_.set_target_channel("stable-channel");
+  params_.set_target_channel(kStableChannel);
 
   // When set to a valid value while a change is already pending, it should
   // succeed.
   params_.Init("", "", {});
-  EXPECT_TRUE(params_.SetTargetChannel("beta-channel", true, nullptr));
+  EXPECT_TRUE(params_.SetTargetChannel(kBetaChannel, true, nullptr));
   // The target channel should reflect the change, but the download channel
   // should continue to retain the old value ...
-  EXPECT_EQ("beta-channel", params_.target_channel());
-  EXPECT_EQ("stable-channel", params_.download_channel());
+  EXPECT_EQ(kBetaChannel, params_.target_channel());
+  EXPECT_EQ(kStableChannel, params_.download_channel());
 
   // ... until we update the download channel explicitly.
   params_.UpdateDownloadChannel();
-  EXPECT_EQ("beta-channel", params_.download_channel());
-  EXPECT_EQ("beta-channel", params_.target_channel());
+  EXPECT_EQ(kBetaChannel, params_.download_channel());
+  EXPECT_EQ(kBetaChannel, params_.target_channel());
 }
 
 TEST_F(OmahaRequestParamsTest, ChannelIndexTest) {
-  int canary = params_.GetChannelIndex("canary-channel");
-  int dev = params_.GetChannelIndex("dev-channel");
-  int beta = params_.GetChannelIndex("beta-channel");
-  int stable = params_.GetChannelIndex("stable-channel");
-  int ltc = params_.GetChannelIndex("ltc-channel");
-  int lts = params_.GetChannelIndex("lts-channel");
+  int canary = params_.GetChannelIndex(kCanaryChannel);
+  int dev = params_.GetChannelIndex(kDevChannel);
+  int beta = params_.GetChannelIndex(kBetaChannel);
+  int stable = params_.GetChannelIndex(kStableChannel);
+  int ltc = params_.GetChannelIndex(kLtcChannel);
+  int lts = params_.GetChannelIndex(kLtsChannel);
   EXPECT_LE(canary, dev);
   EXPECT_LE(dev, beta);
   EXPECT_LE(beta, stable);
@@ -254,12 +254,12 @@ TEST_F(OmahaRequestParamsTest, ChannelIndexTest) {
 }
 
 TEST_F(OmahaRequestParamsTest, ToMoreStableChannelFlagTest) {
-  params_.image_props_.current_channel = "canary-channel";
-  params_.download_channel_ = "stable-channel";
+  params_.image_props_.current_channel = kCanaryChannel;
+  params_.download_channel_ = kStableChannel;
   EXPECT_TRUE(params_.ToMoreStableChannel());
-  params_.image_props_.current_channel = "stable-channel";
+  params_.image_props_.current_channel = kStableChannel;
   EXPECT_FALSE(params_.ToMoreStableChannel());
-  params_.download_channel_ = "beta-channel";
+  params_.download_channel_ = kBetaChannel;
   EXPECT_FALSE(params_.ToMoreStableChannel());
 }
 
@@ -272,8 +272,8 @@ TEST_F(OmahaRequestParamsTest, ShouldPowerwashTest) {
   params_.download_channel_ = "bar-channel";
   EXPECT_TRUE(params_.ShouldPowerwash());
   params_.image_props_.allow_arbitrary_channels = false;
-  params_.image_props_.current_channel = "canary-channel";
-  params_.download_channel_ = "stable-channel";
+  params_.image_props_.current_channel = kCanaryChannel;
+  params_.download_channel_ = kStableChannel;
   EXPECT_TRUE(params_.ShouldPowerwash());
 }
 
@@ -328,9 +328,9 @@ TEST_F(OmahaRequestParamsTest, MiniOsParams) {
 }
 
 TEST_F(OmahaRequestParamsTest, IsCommercialChannel) {
-  EXPECT_TRUE(OmahaRequestParams::IsCommercialChannel("lts-channel"));
-  EXPECT_TRUE(OmahaRequestParams::IsCommercialChannel("ltc-channel"));
-  EXPECT_FALSE(OmahaRequestParams::IsCommercialChannel("stable-channel"));
+  EXPECT_TRUE(OmahaRequestParams::IsCommercialChannel(kLtsChannel));
+  EXPECT_TRUE(OmahaRequestParams::IsCommercialChannel(kLtcChannel));
+  EXPECT_FALSE(OmahaRequestParams::IsCommercialChannel(kStableChannel));
   EXPECT_FALSE(OmahaRequestParams::IsCommercialChannel("foo-channel"));
 }
 
diff --git a/cros/omaha_response_handler_action_unittest.cc b/cros/omaha_response_handler_action_unittest.cc
index 342bee41..d3de2a2a 100644
--- a/cros/omaha_response_handler_action_unittest.cc
+++ b/cros/omaha_response_handler_action_unittest.cc
@@ -510,8 +510,8 @@ TEST_F(OmahaResponseHandlerActionTest,
   OmahaRequestParams params;
   FakeSystemState::Get()->fake_hardware()->SetIsOfficialBuild(false);
   params.set_root(tempdir.GetPath().value());
-  params.set_current_channel("canary-channel");
-  EXPECT_TRUE(params.SetTargetChannel("stable-channel", true, nullptr));
+  params.set_current_channel(kCanaryChannel);
+  EXPECT_TRUE(params.SetTargetChannel(kStableChannel, true, nullptr));
   params.UpdateDownloadChannel();
   params.set_app_version("2.0.0.0");
 
@@ -538,8 +538,8 @@ TEST_F(OmahaResponseHandlerActionTest,
   OmahaRequestParams params;
   FakeSystemState::Get()->fake_hardware()->SetIsOfficialBuild(false);
   params.set_root(tempdir.GetPath().value());
-  params.set_current_channel("canary-channel");
-  EXPECT_TRUE(params.SetTargetChannel("stable-channel", false, nullptr));
+  params.set_current_channel(kCanaryChannel);
+  EXPECT_TRUE(params.SetTargetChannel(kStableChannel, false, nullptr));
   params.UpdateDownloadChannel();
   params.set_app_version("2.0.0.0");
 
@@ -566,8 +566,8 @@ TEST_F(OmahaResponseHandlerActionTest,
   OmahaRequestParams params;
   FakeSystemState::Get()->fake_hardware()->SetIsOfficialBuild(false);
   params.set_root(tempdir.GetPath().value());
-  params.set_current_channel("beta-channel");
-  EXPECT_TRUE(params.SetTargetChannel("stable-channel", true, nullptr));
+  params.set_current_channel(kBetaChannel);
+  EXPECT_TRUE(params.SetTargetChannel(kStableChannel, true, nullptr));
   params.UpdateDownloadChannel();
   params.set_app_version("12345.48.0.0");
 
@@ -594,8 +594,8 @@ TEST_F(OmahaResponseHandlerActionTest,
   OmahaRequestParams params;
   FakeSystemState::Get()->fake_hardware()->SetIsOfficialBuild(false);
   params.set_root(tempdir.GetPath().value());
-  params.set_current_channel("beta-channel");
-  EXPECT_TRUE(params.SetTargetChannel("stable-channel", true, nullptr));
+  params.set_current_channel(kBetaChannel);
+  EXPECT_TRUE(params.SetTargetChannel(kStableChannel, true, nullptr));
   params.UpdateDownloadChannel();
   params.set_app_version("12345.0.0.0");
 
@@ -625,8 +625,8 @@ TEST_F(OmahaResponseHandlerActionTest,
   OmahaRequestParams params;
   FakeSystemState::Get()->fake_hardware()->SetIsOfficialBuild(true);
   params.set_root(tempdir.GetPath().value());
-  params.set_current_channel("beta-channel");
-  EXPECT_TRUE(params.SetTargetChannel("stable-channel", true, nullptr));
+  params.set_current_channel(kBetaChannel);
+  EXPECT_TRUE(params.SetTargetChannel(kStableChannel, true, nullptr));
   params.UpdateDownloadChannel();
   params.set_app_version("12347.48.0.0");
 
@@ -659,8 +659,8 @@ TEST_F(OmahaResponseHandlerActionTest,
   OmahaRequestParams params;
   FakeSystemState::Get()->fake_hardware()->SetIsOfficialBuild(true);
   params.set_root(tempdir.GetPath().value());
-  params.set_current_channel("beta-channel");
-  EXPECT_TRUE(params.SetTargetChannel("stable-channel", true, nullptr));
+  params.set_current_channel(kBetaChannel);
+  EXPECT_TRUE(params.SetTargetChannel(kStableChannel, true, nullptr));
   params.UpdateDownloadChannel();
   params.set_app_version("12347.48.0.0");
 
@@ -692,8 +692,8 @@ TEST_F(OmahaResponseHandlerActionTest,
   OmahaRequestParams params;
   FakeSystemState::Get()->fake_hardware()->SetIsOfficialBuild(true);
   params.set_root(tempdir.GetPath().value());
-  params.set_current_channel("beta-channel");
-  EXPECT_TRUE(params.SetTargetChannel("stable-channel", false, nullptr));
+  params.set_current_channel(kBetaChannel);
+  EXPECT_TRUE(params.SetTargetChannel(kStableChannel, false, nullptr));
   params.UpdateDownloadChannel();
   params.set_app_version("12347.48.0.0");
 
@@ -720,8 +720,8 @@ TEST_F(OmahaResponseHandlerActionTest,
   OmahaRequestParams params;
   FakeSystemState::Get()->fake_hardware()->SetIsOfficialBuild(false);
   params.set_root(tempdir.GetPath().value());
-  params.set_current_channel("stable-channel");
-  EXPECT_TRUE(params.SetTargetChannel("canary-channel", false, nullptr));
+  params.set_current_channel(kStableChannel);
+  EXPECT_TRUE(params.SetTargetChannel(kCanaryChannel, false, nullptr));
   params.UpdateDownloadChannel();
   params.set_app_version("1.0.0.0");
 
diff --git a/cros/update_attempter_unittest.cc b/cros/update_attempter_unittest.cc
index 7c4d3cb6..b1c74d0e 100644
--- a/cros/update_attempter_unittest.cc
+++ b/cros/update_attempter_unittest.cc
@@ -1720,7 +1720,7 @@ TEST_F(UpdateAttempterTest, ChannelDowngradeNoRollback) {
   ASSERT_TRUE(tempdir.CreateUniqueTempDir());
   FakeSystemState::Get()->request_params()->set_root(tempdir.GetPath().value());
   attempter_.CalculateUpdateParams({
-      .target_channel = "stable-channel",
+      .target_channel = kStableChannel,
   });
   EXPECT_FALSE(
       FakeSystemState::Get()->request_params()->is_powerwash_allowed());
@@ -1732,7 +1732,7 @@ TEST_F(UpdateAttempterTest, ChannelDowngradeRollback) {
   FakeSystemState::Get()->request_params()->set_root(tempdir.GetPath().value());
   attempter_.CalculateUpdateParams({
       .rollback_on_channel_downgrade = true,
-      .target_channel = "stable-channel",
+      .target_channel = kStableChannel,
   });
   EXPECT_TRUE(FakeSystemState::Get()->request_params()->is_powerwash_allowed());
 }
diff --git a/update_manager/enterprise_device_policy_impl_unittest.cc b/update_manager/enterprise_device_policy_impl_unittest.cc
index 30f04d28..11b1da91 100644
--- a/update_manager/enterprise_device_policy_impl_unittest.cc
+++ b/update_manager/enterprise_device_policy_impl_unittest.cc
@@ -24,6 +24,7 @@
 #include "update_engine/update_manager/update_check_allowed_policy_data.h"
 
 using chromeos_update_engine::FakeSystemState;
+using chromeos_update_engine::kStableChannel;
 using std::string;
 
 namespace chromeos_update_manager {
@@ -157,7 +158,7 @@ TEST_F(UmEnterpriseDevicePolicyImplTest, ChannelDowngradeBehaviorNoRollback) {
   fake_state_.device_policy_provider()->var_release_channel_delegated()->reset(
       new bool(false));
   fake_state_.device_policy_provider()->var_release_channel()->reset(
-      new std::string("stable-channel"));
+      new std::string(kStableChannel));
 
   EXPECT_EQ(EvalStatus::kContinue, evaluator_->Evaluate());
   EXPECT_FALSE(uca_data_->update_check_params.rollback_on_channel_downgrade);
@@ -167,7 +168,7 @@ TEST_F(UmEnterpriseDevicePolicyImplTest, ChannelDowngradeBehaviorRollback) {
   fake_state_.device_policy_provider()->var_release_channel_delegated()->reset(
       new bool(false));
   fake_state_.device_policy_provider()->var_release_channel()->reset(
-      new std::string("stable-channel"));
+      new std::string(kStableChannel));
   fake_state_.device_policy_provider()->var_channel_downgrade_behavior()->reset(
       new ChannelDowngradeBehavior(ChannelDowngradeBehavior::kRollback));