Adding unit tests for PreviewsOptOutStoreSQL

components/previews/core/previews_experiments.cc

Index: components/previews/core/previews_experiments.cc
diff --git a/components/previews/core/previews_experiments.cc b/components/previews/core/previews_experiments.cc
index fa1fd2fe1b34e867f6a96c8b45adf8e846c5251e..14a4436e9f19a53f5e10e3510367f40d5ab8553e 100644
--- a/components/previews/core/previews_experiments.cc
+++ b/components/previews/core/previews_experiments.cc
@@ -38,20 +38,32 @@ const char kOptOutThreshold[] = "opt_out_threshold";
 
 // 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();
   }
@@ -95,20 +107,35 @@ base::TimeDelta BlackListDuration() {
   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) {