Introduce ExpectApproxEq, a helper function that allows making assertions that certain values are e…

net/quic/test_tools/quic_test_utils.h

Index: net/quic/test_tools/quic_test_utils.h
diff --git a/net/quic/test_tools/quic_test_utils.h b/net/quic/test_tools/quic_test_utils.h
index ab8226a535d4aa91c20452ec89e8a3c0958a76ba..9d89f9a27a047fb7fc31f6aad0e85960e4649d35 100644
--- a/net/quic/test_tools/quic_test_utils.h
+++ b/net/quic/test_tools/quic_test_utils.h
@@ -1033,6 +1033,22 @@ void CreateServerSessionForTest(
 // kClientDataStreamId1 etc. above.
 QuicStreamId QuicClientDataStreamId(int i);
 
+// Verifies that the relative error of |actual| with respect to |expected| is
+// no more than |margin|.
+
+template <typename T>
+void ExpectApproxEq(T expected, T actual, float relative_margin) {
+  // If |relative_margin| > 1 and T is an unsigned type, the comparison will
+  // underflow.
+  ASSERT_LE(relative_margin, 1);
+  ASSERT_GE(relative_margin, 0);
+
+  T absolute_margin = expected * relative_margin;
+
+  EXPECT_GE(expected + absolute_margin, actual);
+  EXPECT_LE(expected - absolute_margin, actual);
+}
+
 }  // namespace test
 }  // namespace net