Bug 1312698 - Add test coverage for the C++ Histogram API. r=dexter

toolkit/components/telemetry/tests/gtest/TestHistograms.cpp

@@ -0,0 +1,54 @@
+/* vim:set ts=2 sw=2 sts=0 et: */
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+#include "gtest/gtest.h"
+#include "js/Conversions.h"
+#include "nsITelemetry.h"
+#include "Telemetry.h"
+#include "TelemetryFixture.h"
+
+TEST_F(TelemetryTestFixture, AccumulateCountHistogram)
+{
+  const uint32_t kExpectedValue = 100;
+  AutoJSContextWithGlobal cx(mCleanGlobal);
+
+  JS::RootedValue testHistogram(cx.GetJSContext());
+  JS::RootedValue rval(cx.GetJSContext());
+
+  // Get the histogram
+  nsresult rv = mTelemetry->GetHistogramById(
+      NS_LITERAL_CSTRING("TELEMETRY_TEST_COUNT"),
+      cx.GetJSContext(),
+      &testHistogram);
+  ASSERT_EQ(rv, NS_OK) << "Cannot fetch histogram";
+
+  // Clear the stored value
+  JS::RootedObject testHistogramObj(cx.GetJSContext(), &testHistogram.toObject());
+  ASSERT_TRUE(JS_CallFunctionName(cx.GetJSContext(), testHistogramObj, "clear",
+                  JS::HandleValueArray::empty(), &rval)) << "Cannot clear histogram";
+
+  // Accumulate in the histogram
+  Telemetry::Accumulate(Telemetry::TELEMETRY_TEST_COUNT, kExpectedValue);
+
+  // Get a snapshot for all the histograms
+  JS::RootedValue snapshot(cx.GetJSContext());
+  rv = mTelemetry->GetHistogramSnapshots(cx.GetJSContext(), &snapshot);
+  ASSERT_EQ(rv, NS_OK) << "Cannot call histogram snapshots";
+
+  // Get the histogram from the snapshot
+  JS::RootedValue histogram(cx.GetJSContext());
+  JS::RootedObject snapshotObj(cx.GetJSContext(), &snapshot.toObject());
+  JS_GetProperty(cx.GetJSContext(), snapshotObj, "TELEMETRY_TEST_COUNT", &histogram);
+
+  // Get the snapshot for the test histogram
+  JS::RootedValue sum(cx.GetJSContext());
+  JS::RootedObject histogramObj(cx.GetJSContext(), &histogram.toObject());
+  JS_GetProperty(cx.GetJSContext(), histogramObj, "sum", &sum);
+
+  // Check that the value stored in the histogram matches with |kExpectedValue|
+  uint32_t uSum = 0;
+  JS::ToUint32(cx.GetJSContext(), sum, &uSum);
+  ASSERT_EQ(uSum, kExpectedValue) << "The histogram is not returning expected value";
+}

toolkit/components/telemetry/tests/gtest/moz.build

@@ -11,7 +11,8 @@ LOCAL_INCLUDES += [
 ]
 
 UNIFIED_SOURCES = [
-    'TestScalars.cpp',
+    'TestHistograms.cpp',
+    'TestScalars.cpp'
 ]
 
 FINAL_LIBRARY = 'xul-gtest'