Add some unittests for DoubleToString.

base/string_number_conversions_unittest.cc

 // Copyright (c) 2011 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 <math.h>
 
 #include <limits>
 
 #include "base/string_number_conversions.h"
 #include "base/utf_string_conversions.h"
@@ skipping 326 matching lines @@
   // One additional test to verify that conversion of numbers in strings with
   // embedded NUL characters.  The NUL and extra data after it should be
   // interpreted as junk after the number.
   const char input[] = "3.14\0159";
   std::string input_string(input, arraysize(input) - 1);
   double output;
   EXPECT_FALSE(StringToDouble(input_string, &output));
   EXPECT_DOUBLE_EQ(3.14, output);
 }
 
+TEST(StringNumberConversionsTest, DoubleToString) {
+  static const struct {
+    double input;
+    std::string expected;

[eroman, 2012/05/14 22:52:39]

I would suggest making this a |const char*| instead. But I see that other
functions in this file use std::string so I guess that is fine.

[Mark Mentovai, 2012/05/14 23:20:32]

eroman wrote:
This should be const char* to avoid an exit-time destructor.

+  } cases[] = {
+    {0.0, "0"},
+    {1.25, "1.25"},
+    {1.33518e+012, "1.33518e+12"},

[eroman, 2012/05/14 22:52:39]

Note that these are NOT the exact same values as I listed in that bug.

1.33518e+12 = 00 00 b0 df ee 6d 73 42
1.33489e+12 = 00 00 e8 4e da 6c 73 42

Whereas in bug 123157 the first two values were:

00 00 00 00 ee 6d 73 42 (1.33518e+12)
00 00 00 a0 da 6c 73 42 (1.33489e+12)

Notice that bytes 2 and 3 are different.

I suggest running at least a local test using the exact same bytes in the
underlying floating point to see if that is tickling anything.

For the purposes of this CL and adding tests, the way you have it written is
fine though.

+    {1.33489e+012, "1.33489e+12"},
+    {1.33505e+012, "1.33505e+12"},
+    {1.33545e+009, "1335450000"},
+    {1.33503e+009, "1335030000"},
+  };
+
+  for (size_t i = 0; i < ARRAYSIZE_UNSAFE(cases); ++i) {
+    EXPECT_EQ(cases[i].expected, DoubleToString(cases[i].input));
+  }
+}
+
 TEST(StringNumberConversionsTest, HexEncode) {
   std::string hex(HexEncode(NULL, 0));
   EXPECT_EQ(hex.length(), 0U);
   unsigned char bytes[] = {0x01, 0xff, 0x02, 0xfe, 0x03, 0x80, 0x81};
   hex = HexEncode(bytes, sizeof(bytes));
   EXPECT_EQ(hex.compare("01FF02FE038081"), 0);
 }
 
 }  // namespace base