Flatten experiment variant to int for ga.js.

hillsp · crowell · commit a2b10e49318e · 2016-04-21T15:24:42.000-04:00
If experiment variant is not an int, inject JS comment with a warning.
diff --git a/net/instaweb/rewriter/insert_ga_filter.cc b/net/instaweb/rewriter/insert_ga_filter.cc
@@ -141,7 +141,15 @@ extern const char kContentExperimentsJsClientUrl[] =
 // before ga.js loads you need to call this.  The first argument is the
 // variant id, the second is the experiment id.
 extern const char kContentExperimentsSetChosenVariationSnippet[] =
-    "cxApi.setChosenVariation('%s', '%s');";
+    "cxApi.setChosenVariation(%d, '%s');";
+
+// When using content experiments with ga.js, the variant ID must be numeric.
+// If the user requests a non-numeric variant with ga.js, we inject this
+// comment. The string is bracketed with newlines because otherwise it's
+// invisible in a wall of JavaScript.
+extern const char kContentExperimentsNonNumericVariantComment[] =
+    "\n/* mod_pagespeed cannot inject experiment variant '%s' "
+    "because it's not a number */\n";
 
 // When using content experiments with analytics.js, after ga('create', ..._)
 // and before ga('[...].send', 'pageview'), we need to insert:
@@ -246,13 +254,30 @@ InsertGAFilter::AnalyticsStatus InsertGAFilter::FindSnippetInScript(
   return kUnusableSnippetFound;
 }
 
-GoogleString InsertGAFilter::AnalyticsJsExperimentSnippet() {
+GoogleString InsertGAFilter::AnalyticsJsExperimentSnippet() const {
   return StringPrintf(
       kContentExperimentsSetExpAndVariantSnippet,
       driver()->options()->content_experiment_id().c_str(),
       driver()->options()->content_experiment_variant_id().c_str());
 }
 
+GoogleString InsertGAFilter::GaJsExperimentSnippet() const {
+  // ga.js requires a numeric variant id. Attempt to convert the string
+  // variant ID to int and use that.
+  const char* variant_id =
+      driver()->options()->content_experiment_variant_id().c_str();
+  int numeric_variant_id;
+  if (StringToInt(variant_id, &numeric_variant_id)) {
+    return StringPrintf(
+        kContentExperimentsSetChosenVariationSnippet, numeric_variant_id,
+        driver()->options()->content_experiment_id().c_str());
+  } else {
+    // Variant ID was non-numeric, so inject a warning.
+    return StringPrintf(kContentExperimentsNonNumericVariantComment,
+                        variant_id);
+  }
+}
+
 // * If we've already inserted any GA snippet or if we found a GA snippet in the
 //   original page, don't do anything.
 // * If we haven't found anything, and haven't inserted anything yet, insert the
@@ -294,11 +319,7 @@ void InsertGAFilter::EndDocument() {
         driver()->AddAttribute(
             cxapi, HtmlName::kSrc, kContentExperimentsJsClientUrl);
         InsertNodeAtBodyEnd(cxapi);
-
-        experiment_snippet = StringPrintf(
-            kContentExperimentsSetChosenVariationSnippet,
-            driver()->options()->content_experiment_variant_id().c_str(),
-            driver()->options()->content_experiment_id().c_str());
+        experiment_snippet = GaJsExperimentSnippet();
       } else {
         experiment_snippet = StringPrintf(
             kGAExperimentSnippet,
@@ -515,15 +536,11 @@ void InsertGAFilter::RewriteInlineScript(HtmlCharactersNode* characters) {
 void InsertGAFilter::HandleEndScript(HtmlElement* script) {
   if (!postponed_script_body_.empty()) {
     DCHECK(script == script_element_);
-    GoogleString snippet_text = StringPrintf(
-        kContentExperimentsSetChosenVariationSnippet,
-        driver()->options()->content_experiment_variant_id().c_str(),
-        driver()->options()->content_experiment_id().c_str());
-
     driver()->InsertScriptAfterCurrent(
         kContentExperimentsJsClientUrl, true /* external */);
     driver()->InsertScriptAfterCurrent(
-        StrCat(snippet_text, postponed_script_body_), false /* inline */);
+        StrCat(GaJsExperimentSnippet(), postponed_script_body_),
+        false /* inline */);
     added_experiment_snippet_ = true;
     postponed_script_body_.clear();
   }
diff --git a/net/instaweb/rewriter/insert_ga_filter_test.cc b/net/instaweb/rewriter/insert_ga_filter_test.cc
@@ -252,19 +252,24 @@ class InsertGAFilterTest : public RewriteTestBase {
   }
 
   void SetUpContentExperiment(bool use_analytics_js) {
+    SetUpContentExperiment(use_analytics_js, "456");
+  }
+
+  void SetUpContentExperiment(bool use_analytics_js,
+                              const GoogleString& variant_id) {
     NullMessageHandler handler;
     RewriteOptions* options = rewrite_driver()->options()->Clone();
     options->set_use_analytics_js(use_analytics_js);
     options->set_running_experiment(true);
-    ASSERT_TRUE(options->AddExperimentSpec(
+    ASSERT_TRUE(options->AddExperimentSpec(StringPrintf(
         "id=2;percent=10;slot=4;options="
         "ContentExperimentID=123,"
-        "ContentExperimentVariantID=456", &handler));
+        "ContentExperimentVariantID=%s", variant_id.c_str()), &handler));
     ASSERT_TRUE(options->AddExperimentSpec(
         "id=7;percent=10;level=CoreFilters;slot=4;options="
         "ContentExperimentID=123,"
         "ContentExperimentVariantID=789", &handler));
-    options->SetExperimentState(2);  // Expecting cxid=123, cxvid=456.
+    options->SetExperimentState(2);  // Expecting cxid=123, cxvid=variant_id.
 
     // Setting up experiments automatically enables AddInstrumentation.
     // Turn it off so our output is easier to understand.
@@ -376,7 +381,25 @@ TEST_F(InsertGAFilterTest, ExperimentGaJsCx) {
              "\"></script>").c_str(),
       "",
       StrCat(StringPrintf(kContentExperimentsSetChosenVariationSnippet,
-                          "456", "123"),
+                          456, "123"),
+             StringPrintf(kGAJsSnippet, kGaId, "test.com",
+                          kGASpeedTracking)).c_str());
+  ValidateExpected("ga.js cx experiment", kHtmlInput, output);
+}
+
+TEST_F(InsertGAFilterTest, ExperimentGaJsCxString) {
+  // Show that an attempt to insert a ga.js snippet with a string variant ID
+  // results in a warning message.
+  const GoogleString& kVariantText("StringVariant");
+  SetUpContentExperiment(false, kVariantText);
+  GoogleString output = StringPrintf(
+      kHtmlOutputFormat,
+      StrCat("<script src=\"",
+             kContentExperimentsJsClientUrl,
+             "\"></script>").c_str(),
+      "",
+      StrCat(StringPrintf(kContentExperimentsNonNumericVariantComment,
+                          kVariantText.c_str()),
              StringPrintf(kGAJsSnippet, kGaId, "test.com",
                           kGASpeedTracking)).c_str());
   ValidateExpected("ga.js cx experiment", kHtmlInput, output);
@@ -411,6 +434,21 @@ TEST_F(InsertGAFilterTest, ExperimentAnalyticsJsCx) {
   ValidateExpected("analytics.js cx experiment", kHtmlInput, output);
 }
 
+TEST_F(InsertGAFilterTest, ExperimentAnalyticsJsCxString) {
+  // Show that we can insert an anlytics.js snippet that includes content
+  // experiment tracking where the variant is a string.
+  const GoogleString& kVariantText("StringVariant");
+  SetUpContentExperiment(true, kVariantText);
+  GoogleString output =  StringPrintf(
+      kHtmlOutputFormat, "", "", StringPrintf(
+          kAnalyticsJsSnippet,
+          kGaId,
+          kAnalyticsJsIncreaseSiteSpeedTracking,
+          StringPrintf(kContentExperimentsSetExpAndVariantSnippet,
+                       "123", kVariantText.c_str()).c_str()).c_str());
+  ValidateExpected("analytics.js cx experiment", kHtmlInput, output);
+}
+
 const char kHtmlInputWithGASnippetFormat[] =
     "<head>\n<title>Something</title>\n"
     "</head><body> Hello World!"
@@ -529,7 +567,7 @@ TEST_F(InsertGAFilterTest, SynchronousGAContentExperiment) {
                        "\"></script><script>",
                        StringPrintf(
                            kContentExperimentsSetChosenVariationSnippet,
-                           "456", "123")).c_str(),
+                           456, "123")).c_str(),
                    kGaId);
   ValidateExpected("extend sync ga.js for content experiment", input, output);
 }
@@ -568,7 +606,7 @@ TEST_F(InsertGAFilterTest, AsynchronousGAContentExperiment) {
                        "\"></script><script>",
                        StringPrintf(
                            kContentExperimentsSetChosenVariationSnippet,
-                           "456", "123")).c_str(),
+                           456, "123")).c_str(),
                    kGaId);
   ValidateExpected("extend async ga.js for content experiment", input, output);
 }
@@ -764,7 +802,7 @@ TEST_F(InsertGAFilterTest, ExistingGaJsContentExperimentNoCloseAnything) {
              "\"></script>"
              "<script>",
              StringPrintf(kContentExperimentsSetChosenVariationSnippet,
-                          "456", "123"),
+                          456, "123"),
              StringPrintf(kGAJsSnippet, kGaId, "test.com",
                           kGASpeedTracking)).c_str());
 
@@ -786,7 +824,7 @@ TEST_F(InsertGAFilterTest, AsynchronousGAContentExperimentFlush) {
                        "\"></script><script>",
                        StringPrintf(
                            kContentExperimentsSetChosenVariationSnippet,
-                           "456", "123")).c_str(),
+                           456, "123")).c_str(),
                    kGaId);
 
   SetupWriter();
diff --git a/net/instaweb/rewriter/public/insert_ga_filter.h b/net/instaweb/rewriter/public/insert_ga_filter.h
@@ -42,6 +42,7 @@ extern const char kAnalyticsJsSnippet[];
 extern const char kAnalyticsJsIncreaseSiteSpeedTracking[];
 extern const char kAnalyticsJsIncreaseSiteSpeedTrackingMinimal[];
 extern const char kContentExperimentsJsClientUrl[];
+extern const char kContentExperimentsNonNumericVariantComment[];
 extern const char kContentExperimentsSetChosenVariationSnippet[];
 extern const char kContentExperimentsSetExpAndVariantSnippet[];
 extern const char kGASpeedTracking[];
@@ -112,9 +113,9 @@ class InsertGAFilter : public CommonFilter {
   // snippet depends in part on whether we've already seen a ga.js library load.
   AnalyticsStatus FindSnippetInScript(const GoogleString& s);
 
-  // Determine the snippet of JS we need to log a content experiment to
-  // analytics.js.
-  GoogleString AnalyticsJsExperimentSnippet();
+  // Determine the snippet of JS we need to log a content experiment.
+  GoogleString AnalyticsJsExperimentSnippet() const;
+  GoogleString GaJsExperimentSnippet() const;
 
   // Note: logs a warning if we're running with analytics.js and have asked it
   // to log to a custom variable (which isn't possible).
