Add format width and precision tests.

core/src/fxcrt/fx_basic_bstring_unittest.cpp

 // Copyright 2014 PDFium 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 "../../../testing/fx_string_testhelpers.h"
 #include "../../include/fxcrt/fx_string.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 TEST(fxcrt, ByteStringOperatorSubscript) {
   // CFX_ByteString includes the NUL terminator for non-empty strings.
@@ skipping 585 matching lines @@
   const char* c_string2 = "hellp";
   const char* c_string3 = "hellod";
   EXPECT_TRUE(byte_string_c != c_string1);
   EXPECT_TRUE(byte_string_c != c_string2);
   EXPECT_TRUE(byte_string_c != c_string3);
 
   EXPECT_TRUE(c_string1 != byte_string_c);
   EXPECT_TRUE(c_string2 != byte_string_c);
   EXPECT_TRUE(c_string3 != byte_string_c);
 }
+
+TEST(fxcrt, ByteStringFormatWidth) {
+  {
+    CFX_ByteString str;

[Tom Sepez, 2015/11/03 17:19:49]

Do these support the %*d syntax as well?  If so, can we test that.
Also, what happens if we put in a negative value or 0 value, eg
%-1d or %0d?

[dsinclair, 2015/11/03 18:50:08]

Done.

+    str.Format("%5d", 1);
+    EXPECT_EQ("    1", str);
+  }
+
+  {
+    CFX_ByteString str;
+    str.Format("%d", 1);
+    EXPECT_EQ("1", str);
+  }
+}
+
+TEST(fxcrt, ByteStringFormatPrecision) {
+  {
+    CFX_ByteString str;
+    str.Format("%.2f", 1.12345);
+    EXPECT_EQ("1.12", str);
+  }
+
+  {
+    CFX_ByteString str;
+    str.Format("%f", 1.12345);
+    EXPECT_EQ("1.123450", str);
+  }
+}