From 13160d93b25d2491bf511de9eeb21bebf05cb7ad Mon Sep 17 00:00:00 2001
From: abolz <lt.morris.schaffer@googlemail.com>
Date: Fri, 8 Dec 2017 15:18:32 +0100
Subject: [PATCH] Add tests for #360

---
 test/src/unit-regression.cpp | 58 ++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/test/src/unit-regression.cpp b/test/src/unit-regression.cpp
index 8eff9d764..556db4950 100644
--- a/test/src/unit-regression.cpp
+++ b/test/src/unit-regression.cpp
@@ -593,6 +593,64 @@ TEST_CASE("regression tests")
                           "[json.exception.out_of_range.406] number overflow parsing '22e2222'");
     }
 
+    SECTION("issue #360 - Loss of precision when serializing <double>")
+    {
+        auto CheckRoundtrip = [](double number)
+        {
+            CAPTURE(number);
+
+            json j = number;
+            CHECK(j.is_number_float());
+
+            std::stringstream ss;
+            ss << j;
+
+            CHECK_NOTHROW(ss >> j);
+            CHECK(j.is_number_float());
+            CHECK(j.get<json::number_float_t>() == number);
+        };
+
+        CheckRoundtrip(100000000000.1236);
+        CheckRoundtrip(std::numeric_limits<json::number_float_t>::max());
+        // Some more numbers which fail to roundtrip when serialized with
+        // digits10 significand digits (instead of max_digits10)
+        CheckRoundtrip(1.541888611948064e-17);
+        CheckRoundtrip(5.418771028591015e-16);
+        CheckRoundtrip(9.398685592608595e-15);
+        CheckRoundtrip(8.826843952762347e-14);
+        CheckRoundtrip(8.143291313475335e-13);
+        CheckRoundtrip(4.851328172762508e-12);
+        CheckRoundtrip(6.677850998084358e-11);
+        CheckRoundtrip(3.995398518174525e-10);
+        CheckRoundtrip(1.960452605645124e-9);
+        CheckRoundtrip(3.551812586302883e-8);
+        CheckRoundtrip(2.947988411689261e-7);
+        CheckRoundtrip(8.210166748056192e-6);
+        CheckRoundtrip(6.104889704266753e-5);
+        CheckRoundtrip(0.0008629954631330876);
+        CheckRoundtrip(0.004936993881051611);
+        CheckRoundtrip(0.08309725102608073);
+        CheckRoundtrip(0.5210494268499783);
+        CheckRoundtrip(6.382927930939767);
+        CheckRoundtrip(59.94947245358671);
+        CheckRoundtrip(361.0838651266122);
+        CheckRoundtrip(4678.354596181877);
+        CheckRoundtrip(61412.17658956043);
+        CheckRoundtrip(725696.0799057782);
+        CheckRoundtrip(2811732.583399828);
+        CheckRoundtrip(30178351.07533605);
+        CheckRoundtrip(689684880.3235844);
+        CheckRoundtrip(5714887673.555147);
+        CheckRoundtrip(84652038821.18808);
+        CheckRoundtrip(156510583431.7721);
+        CheckRoundtrip(5938450569021.732);
+        CheckRoundtrip(83623297654460.33);
+        CheckRoundtrip(701466573254773.6);
+        CheckRoundtrip(1369013370304513);
+        CheckRoundtrip(96963648023094720);
+        CheckRoundtrip(3.478237409280108e+17);
+    }
+
     SECTION("issue #366 - json::parse on failed stream gets stuck")
     {
         std::ifstream f("file_not_found.json");