diff --git a/common/test_utils.h b/common/test_utils.h
index bb5a678..631ded4 100644
--- a/common/test_utils.h
+++ b/common/test_utils.h
@@ -33,6 +33,7 @@
 #include <gtest/gtest.h>
 
 #include "update_engine/common/action.h"
+#include "update_engine/common/testing_constants.h"
 #include "update_engine/common/utils.h"
 #include "update_engine/update_metadata.pb.h"
 
diff --git a/common/testing_constants.h b/common/testing_constants.h
new file mode 100644
index 0000000..1367ce6
--- /dev/null
+++ b/common/testing_constants.h
@@ -0,0 +1,39 @@
+//
+// Copyright (C) 2021 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.
+//
+
+#ifndef UPDATE_ENGINE_COMMON_TESTING_CONSTANTS_H_
+#define UPDATE_ENGINE_COMMON_TESTING_CONSTANTS_H_
+
+[[maybe_unused]]
+static constexpr auto&& kUnittestPrivateKeyPath = "unittest_key.pem";
+[[maybe_unused]]
+static constexpr auto&& kUnittestPublicKeyPath = "unittest_key.pub.pem";
+[[maybe_unused]]
+static constexpr auto&& kUnittestPrivateKey2Path = "unittest_key2.pem";
+[[maybe_unused]]
+static constexpr auto&& kUnittestPublicKey2Path = "unittest_key2.pub.pem";
+[[maybe_unused]]
+static constexpr auto&& kUnittestPrivateKeyRSA4096Path =
+    "unittest_key_RSA4096.pem";
+[[maybe_unused]]
+static constexpr auto&& kUnittestPublicKeyRSA4096Path =
+    "unittest_key_RSA4096.pub.pem";
+[[maybe_unused]]
+static constexpr auto&& kUnittestPrivateKeyECPath = "unittest_key_EC.pem";
+[[maybe_unused]]
+static constexpr auto&& kUnittestPublicKeyECPath = "unittest_key_EC.pub.pem";
+
+#endif  // UPDATE_ENGINE_COMMON_TESTING_CONSTANTS_H_
diff --git a/download_action_android_unittest.cc b/download_action_android_unittest.cc
index fef2d24..0f7ecdc 100644
--- a/download_action_android_unittest.cc
+++ b/download_action_android_unittest.cc
@@ -32,6 +32,7 @@
 #include "update_engine/common/mock_action_processor.h"
 #include "update_engine/common/mock_http_fetcher.h"
 #include "update_engine/common/mock_prefs.h"
+#include "update_engine/common/testing_constants.h"
 #include "update_engine/common/test_utils.h"
 #include "update_engine/common/utils.h"
 #include "update_engine/payload_consumer/install_plan.h"
@@ -46,9 +47,6 @@
 using testing::Return;
 using testing::SetArgPointee;
 
-extern const char* kUnittestPrivateKeyPath;
-extern const char* kUnittestPublicKeyPath;
-
 class DownloadActionTest : public ::testing::Test {
  public:
   static constexpr int64_t METADATA_SIZE = 1024;
diff --git a/payload_consumer/certificate_parser_android_unittest.cc b/payload_consumer/certificate_parser_android_unittest.cc
index e300414..9603f96 100644
--- a/payload_consumer/certificate_parser_android_unittest.cc
+++ b/payload_consumer/certificate_parser_android_unittest.cc
@@ -21,15 +21,15 @@
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
 
-#include "update_engine/common/hash_calculator.h"
 #include "update_engine/common/test_utils.h"
+#include "update_engine/common/testing_constants.h"
+#include "update_engine/common/hash_calculator.h"
 #include "update_engine/common/utils.h"
 #include "update_engine/payload_consumer/payload_verifier.h"
 #include "update_engine/payload_generator/payload_signer.h"
 
 namespace chromeos_update_engine {
 
-extern const char* kUnittestPrivateKeyPath;
 const char* kUnittestOtacertsPath = "otacerts.zip";
 
 TEST(CertificateParserAndroidTest, ParseZipArchive) {
diff --git a/payload_consumer/delta_performer.cc b/payload_consumer/delta_performer.cc
index 274465c..a383bf6 100644
--- a/payload_consumer/delta_performer.cc
+++ b/payload_consumer/delta_performer.cc
@@ -247,8 +247,8 @@
       IsDynamicPartition(install_part.name, install_plan_->target_slot));
   // Open source fds if we have a delta payload, or for partitions in the
   // partial update.
-  bool source_may_exist = manifest_.partial_update() ||
-                          payload_->type == InstallPayloadType::kDelta;
+  const bool source_may_exist = manifest_.partial_update() ||
+                                payload_->type == InstallPayloadType::kDelta;
   const size_t partition_operation_num = GetPartitionOperationNum();
 
   TEST_AND_RETURN_FALSE(partition_writer_->Init(
@@ -1146,9 +1146,12 @@
   // Verifies the payload hash.
   TEST_AND_RETURN_VAL(ErrorCode::kDownloadPayloadVerificationError,
                       !payload_hash_calculator_.raw_hash().empty());
-  TEST_AND_RETURN_VAL(
-      ErrorCode::kPayloadHashMismatchError,
-      payload_hash_calculator_.raw_hash() == update_check_response_hash);
+  if (payload_hash_calculator_.raw_hash() != update_check_response_hash) {
+    LOG(ERROR) << "Actual hash: "
+               << HexEncode(payload_hash_calculator_.raw_hash())
+               << ", expected hash: " << HexEncode(update_check_response_hash);
+    return ErrorCode::kPayloadHashMismatchError;
+  }
 
   // NOLINTNEXTLINE(whitespace/braces)
   auto [payload_verifier, perform_verification] = CreatePayloadVerifier();
diff --git a/payload_consumer/delta_performer_integration_test.cc b/payload_consumer/delta_performer_integration_test.cc
index a72b8ae..34e4c90 100644
--- a/payload_consumer/delta_performer_integration_test.cc
+++ b/payload_consumer/delta_performer_integration_test.cc
@@ -41,6 +41,7 @@
 #include "update_engine/common/mock_download_action.h"
 #include "update_engine/common/mock_prefs.h"
 #include "update_engine/common/test_utils.h"
+#include "update_engine/common/testing_constants.h"
 #include "update_engine/common/utils.h"
 #include "update_engine/payload_consumer/install_plan.h"
 #include "update_engine/payload_consumer/payload_constants.h"
@@ -66,13 +67,6 @@
 using testing::Not;
 using testing::Return;
 
-extern const char* kUnittestPrivateKeyPath;
-extern const char* kUnittestPublicKeyPath;
-extern const char* kUnittestPrivateKey2Path;
-extern const char* kUnittestPublicKey2Path;
-extern const char* kUnittestPrivateKeyECPath;
-extern const char* kUnittestPublicKeyECPath;
-
 static const uint32_t kDefaultKernelSize = 4096;  // Something small for a test
 // clang-format off
 static const uint8_t kNewData[] = {'T', 'h', 'i', 's', ' ', 'i', 's', ' ',
diff --git a/payload_consumer/delta_performer_unittest.cc b/payload_consumer/delta_performer_unittest.cc
index c24c524..bd4850a 100644
--- a/payload_consumer/delta_performer_unittest.cc
+++ b/payload_consumer/delta_performer_unittest.cc
@@ -47,6 +47,7 @@
 #include "update_engine/common/hash_calculator.h"
 #include "update_engine/common/mock_download_action.h"
 #include "update_engine/common/test_utils.h"
+#include "update_engine/common/testing_constants.h"
 #include "update_engine/common/utils.h"
 #include "update_engine/payload_consumer/fake_file_descriptor.h"
 #include "update_engine/payload_consumer/mock_partition_writer.h"
@@ -68,9 +69,6 @@
 using testing::Return;
 using ::testing::Sequence;
 
-extern const char* kUnittestPrivateKeyPath;
-extern const char* kUnittestPublicKeyPath;
-
 namespace {
 
 const char kBogusMetadataSignature1[] =
diff --git a/payload_generator/delta_diff_generator.cc b/payload_generator/delta_diff_generator.cc
index c6c70ef..46dfb0f 100644
--- a/payload_generator/delta_diff_generator.cc
+++ b/payload_generator/delta_diff_generator.cc
@@ -53,7 +53,6 @@
 
 // bytes
 const size_t kRootFSPartitionSize = static_cast<size_t>(2) * 1024 * 1024 * 1024;
-const size_t kBlockSize = 4096;  // bytes
 
 class PartitionProcessor : public base::DelegateSimpleThread::Delegate {
   bool IsDynamicPartition(const std::string& partition_name) {
diff --git a/payload_generator/delta_diff_generator.h b/payload_generator/delta_diff_generator.h
index 8323f47..b11f30a 100644
--- a/payload_generator/delta_diff_generator.h
+++ b/payload_generator/delta_diff_generator.h
@@ -23,7 +23,7 @@
 
 namespace chromeos_update_engine {
 
-extern const size_t kBlockSize;
+constexpr size_t kBlockSize = 4096;
 extern const size_t kRootFSPartitionSize;
 
 // The |config| describes the payload generation request, describing both
diff --git a/payload_generator/payload_signer_unittest.cc b/payload_generator/payload_signer_unittest.cc
index 2a0b394..2bfc820 100644
--- a/payload_generator/payload_signer_unittest.cc
+++ b/payload_generator/payload_signer_unittest.cc
@@ -25,6 +25,7 @@
 
 #include "update_engine/common/hash_calculator.h"
 #include "update_engine/common/test_utils.h"
+#include "update_engine/common/testing_constants.h"
 #include "update_engine/common/utils.h"
 #include "update_engine/payload_consumer/payload_constants.h"
 #include "update_engine/payload_consumer/payload_verifier.h"
@@ -41,15 +42,6 @@
 
 namespace chromeos_update_engine {
 
-const char* kUnittestPrivateKeyPath = "unittest_key.pem";
-const char* kUnittestPublicKeyPath = "unittest_key.pub.pem";
-const char* kUnittestPrivateKey2Path = "unittest_key2.pem";
-const char* kUnittestPublicKey2Path = "unittest_key2.pub.pem";
-const char* kUnittestPrivateKeyRSA4096Path = "unittest_key_RSA4096.pem";
-const char* kUnittestPublicKeyRSA4096Path = "unittest_key_RSA4096.pub.pem";
-const char* kUnittestPrivateKeyECPath = "unittest_key_EC.pem";
-const char* kUnittestPublicKeyECPath = "unittest_key_EC.pub.pem";
-
 // Some data and its corresponding hash and signature:
 const char kDataToSign[] = "This is some data to sign.";