Index: components/rappor/rappor_metric_unittest.cc |
diff --git a/components/rappor/rappor_metric_unittest.cc b/components/rappor/rappor_metric_unittest.cc |
new file mode 100644 |
index 0000000000000000000000000000000000000000..59943fba8901142aa9d96489ffd735371ab5a5a1 |
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+++ b/components/rappor/rappor_metric_unittest.cc |
@@ -0,0 +1,95 @@ |
+// Copyright 2014 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/rappor/rappor_metric.h" |
+ |
+#include <stdlib.h> |
+ |
+#include "base/rand_util.h" |
+#include "base/strings/stringprintf.h" |
+#include "testing/gtest/include/gtest/gtest.h" |
+ |
+namespace rappor { |
+ |
+const RapporParameters kTestRapporParameters = { |
+ 16 /* Bloom filter size bytes */, |
+ 4 /* Bloom filter hash count */, |
+ PROBABILITY_75 /* Fake data probability */, |
+ PROBABILITY_50 /* Fake one probability */, |
+ PROBABILITY_75 /* One coin probability */, |
+ PROBABILITY_50 /* Zero coin probability */ |
+}; |
+ |
+const RapporParameters kTestStatsRapporParameters = { |
+ 50 /* Bloom filter size bytes */, |
+ 4 /* Bloom filter hash count */, |
+ PROBABILITY_75 /* Fake data probability */, |
+ PROBABILITY_50 /* Fake one probability */, |
+ PROBABILITY_75 /* One coin probability */, |
+ PROBABILITY_50 /* Zero coin probability */ |
+}; |
+ |
+// Check for basic syntax and use. |
+TEST(RapporMetricTest, BasicTest) { |
+ RapporMetric testMetric("MyRappor", kTestRapporParameters, 0); |
+ testMetric.AddSample("Foo"); |
+ testMetric.AddSample("Bar"); |
+ EXPECT_EQ(0x80, testMetric.bytes()[1]); |
+} |
+ |
+TEST(RapporMetricTest, GetReportTest) { |
+ RapporMetric metric("MyRappor", kTestRapporParameters, 0); |
+ |
+ ByteVector report = metric.GetReport("MySecret"); |
+ EXPECT_EQ(16u, report.size()); |
+} |
+ |
+TEST(RapporMetricTest, GetReportStatistical) { |
+ RapporMetric metric("MyStatsRappor", kTestStatsRapporParameters, 0); |
+ |
+ for (char i = 0; i < 50; i++) { |
+ metric.AddSample(base::StringPrintf("%d", i)); |
+ } |
+ ByteVector real_bits = metric.bytes(); |
+ int real_bit_count = CountBits(real_bits); |
+ EXPECT_EQ(real_bit_count, 152); |
+ |
+ std::string secret = base::RandBytesAsString(128); |
+ ByteVector report = metric.GetReport(secret); |
+ |
+ // For the bits we actually set in the bloom filter, get a count of how |
+ // many of them reported true. |
+ ByteVector from_true_reports = report; |
+ // Real bits AND report bits. |
+ ByteVectorMerge(real_bits, real_bits, &from_true_reports); |
+ int true_from_true_count = CountBits(from_true_reports); |
+ |
+ // For the bits we didn't set in the bloom filter, get a count of how |
+ // many of them reported true. |
+ ByteVector from_false_reports = report; |
+ ByteVectorOr(real_bits, &from_false_reports); |
+ int true_from_false_count = CountBits(from_false_reports) - real_bit_count; |
+ |
+ // The probability of a true bit being true after redaction = |
+ // [fake_prob]*[fake_true_prob] + (1-[fake_prob]) = |
+ // .75 * .5 + (1-.75) = .625 |
+ // The probablity of a false bit being true after redaction = |
+ // [fake_prob]*[fake_true_prob] = .375 |
+ // The probability of a bit reporting true = |
+ // [redacted_prob] * .75 + (1-[redacted_prob] * .5) = |
+ // 0.65625 for true bits |
+ // 0.59375 for false bits |
+ |
+ // stats.binom(152, 0.65625).ppf(0.000005) = 73 |
+ EXPECT_GT(true_from_true_count, 73); |
+ // stats.binom(152, 0.65625).ppf(0.999995) = 124 |
+ EXPECT_LE(true_from_true_count, 124); |
+ |
+ // stats.binom(248, 0.59375).ppf(.000005) = 113 |
+ EXPECT_GT(true_from_false_count, 113); |
+ // stats.binom(248, 0.59375).ppf(.999995) = 181 |
+ EXPECT_LE(true_from_false_count, 181); |
+} |
+ |
+} // namespace rappor |