set a default empty policy_test_server.

Set a default empty policy file for policy_test_server. Only
warn when the file is missing.

Bug: chromium:668719
Change-Id: I474587cdf810716d485c3dca1aefb4f513cbbe22
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2215050Reviewed-by: Denis Kuznetsov [CET] <antrim@chromium.org>
Reviewed-by: Maksim Ivanov <emaxx@chromium.org>
Commit-Queue: Victor-Gabriel Savu <vsavu@google.com>
Cr-Commit-Position: refs/heads/master@{#776640}

components/policy/test_support/local_policy_test_server.cc

@@ -68,6 +68,10 @@ bool IsUnsafeCharacter(char c) {
 LocalPolicyTestServer::LocalPolicyTestServer()
     : LocalPolicyTestServer(base::FilePath()) {
   config_file_ = server_data_dir_.GetPath().Append(kPolicyFileName);
+
+  if (!PathExists(config_file_)) {
+    SetEmptyConfig();
+  }
 }
 
 LocalPolicyTestServer::LocalPolicyTestServer(const base::FilePath& config_file)
@@ -76,6 +80,10 @@ LocalPolicyTestServer::LocalPolicyTestServer(const base::FilePath& config_file)
   base::ScopedAllowBlockingForTesting allow_blocking;
   CHECK(server_data_dir_.CreateUniqueTempDir());
   client_state_file_ = server_data_dir_.GetPath().Append(kClientStateFileName);
+
+  if (!config_file_.empty() && !PathExists(config_file_)) {
+    SetEmptyConfig();
+  }
 }
 
 LocalPolicyTestServer::LocalPolicyTestServer(
@@ -288,4 +296,10 @@ std::string LocalPolicyTestServer::GetSelector(const std::string& type,
   return selector;
 }
 
+void LocalPolicyTestServer::SetEmptyConfig() {
+  if (!SetConfig(base::Value(base::Value::Type::DICTIONARY))) {
+    LOG(ERROR) << "Failed to write empty config " << config_file_.value();
+  }
+}
+
 }  // namespace policy

components/policy/test_support/local_policy_test_server.h

@@ -100,6 +100,8 @@ class LocalPolicyTestServer : public net::LocalTestServer {
   std::string GetSelector(const std::string& type,
                           const std::string& entity_id);
 
+  void SetEmptyConfig();
+
   base::FilePath config_file_;
   base::FilePath policy_key_;
   base::FilePath client_state_file_;

components/policy/test_support/policy_testserver.py

@@ -1394,7 +1394,9 @@ class PolicyTestServer(testserver_base.BrokenPipeHandlerMixIn,
     policy = {}
     if json is None:
       logging.error('No JSON module, cannot parse policy information')
-    else :
+    elif not os.path.exists(self.policy_path):
+      logging.warning('Missing policies file %s' % self.policy_path)
+    else:
       try:
         policy = json.loads(open(self.policy_path).read(), strict=False)
       except IOError: