Adding unit tests for PreviewsOptOutStoreSQL

components/previews/core/previews_experiments.cc

 // Copyright 2016 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 "components/previews/core/previews_experiments.h"
 
 #include <map>
 #include <string>
 
 #include "base/logging.h"
@@ skipping 27 matching lines @@
 
 // The amount of time a host remains blacklisted due to opt outs.
 const char kBlackListDurationInDays[] = "black_list_duration_in_days";
 
 // The string that corresponds to enabled for the variation param experiments.
 const char kExperimentEnabled[] = "true";
 
 // In seconds. Hosts are blacklisted for 30 days.
 constexpr int kDefaultBlackListDurationInDays = 30;
 
+// Command line switch to change the previews per row DB size.

[tbansal1, 2016/10/28 22:07:14]

why is there a need to set this using command line switches?
Is it possible to add a virtual method, and override in tests?

[RyanSturm, 2016/11/03 18:30:03]

I moved this to previews_opt_out_store_sql.cc

I want to avoid injecting these values into the constructor, and I don't think
changing static/anonymous methods to class methods or plumbing these values down
is a better approach.

+const char kMaxRowsPerHost[] = "previews-max-opt-out-rows-per-host";
+
+// Command line switch to change the previews DB size.
+const char kMaxRows[] = "previews-max-opt-out-rows";
+
+// The maximum number of entries allowed per host in the SQLite DB.
+const int kDefaultMaxRowsPerHost = 32;
+
+// The maximum number of entries allowed in the SQLite DB.
+const int kDefaultMaxRowsInDB = 3200;
+
 // Returns the parameter value of |param| as a string. If there is no value for
 // |param|, returns an empty string.
 std::string ParamValue(const std::string& param) {
   if (!IsIncludedInClientSidePreviewsExperimentsFieldTrial())
     return std::string();
   std::map<std::string, std::string> experiment_params;
   if (!variations::GetVariationParams(kClientSidePreviewsFieldTrial,
                                       &experiment_params)) {
     return std::string();
   }
@@ skipping 37 matching lines @@
   std::string param_value = ParamValue(kBlackListDurationInDays);
   int duration;
   if (!base::StringToInt(param_value, &duration)) {
     return base::TimeDelta::FromDays(kDefaultBlackListDurationInDays);
   }
   return base::TimeDelta::FromDays(duration);
 }
 
 }  // namespace params
 
+int MaxRowsPerHostInOptOutDB() {
+  std::string max_rows =
+      base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+          kMaxRowsPerHost);
+  int value;
+  return base::StringToInt(max_rows, &value) ? value : kDefaultMaxRowsPerHost;
+}
+
+int MaxRowsInOptOutDB() {
+  std::string max_rows =
+      base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(kMaxRows);
+  int value;
+  return base::StringToInt(max_rows, &value) ? value : kDefaultMaxRowsInDB;
+}
+
 bool IsIncludedInClientSidePreviewsExperimentsFieldTrial() {
   // By convention, an experiment in the client-side previews study enables use
   // of at least one client-side previews optimization if its name begins with
   // "Enabled."
   return base::StartsWith(
       base::FieldTrialList::FindFullName(kClientSidePreviewsFieldTrial),
       kEnabled, base::CompareCase::SENSITIVE);
 }
 
 bool IsPreviewsTypeEnabled(PreviewsType type) {
   switch (type) {
     case PreviewsType::OFFLINE:
       return ParamValue(kOfflinePagesSlowNetwork) == kExperimentEnabled;
     default:
       NOTREACHED();
       return false;
   }
 }
 
 bool EnableOfflinePreviewsForTesting() {
   std::map<std::string, std::string> params;
   params[kOfflinePagesSlowNetwork] = kExperimentEnabled;
   return variations::AssociateVariationParams(kClientSidePreviewsFieldTrial,
                                               kEnabled, params) &&
          base::FieldTrialList::CreateFieldTrial(kClientSidePreviewsFieldTrial,
                                                 kEnabled);
 }
 
 }  // namespace previews