Add format width and precision tests.

core/src/fxcrt/fx_basic_wstring_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/gtest/include/gtest/gtest.h"
 #include "../../../testing/fx_string_testhelpers.h"
 #include "../../include/fxcrt/fx_basic.h"
 
 TEST(fxcrt, WideStringOperatorSubscript) {
   // CFX_WideString includes the NUL terminator for non-empty strings.
@@ skipping 422 matching lines @@
   const wchar_t* c_string2 = L"hellp";
   const wchar_t* c_string3 = L"hellod";
   EXPECT_TRUE(wide_string_c != c_string1);
   EXPECT_TRUE(wide_string_c != c_string2);
   EXPECT_TRUE(wide_string_c != c_string3);
 
   EXPECT_TRUE(c_string1 != wide_string_c);
   EXPECT_TRUE(c_string2 != wide_string_c);
   EXPECT_TRUE(c_string3 != wide_string_c);
 }
+
+TEST(fxcrt, WideStringFormatWidth) {
+  {
+    CFX_WideString str;
+    str.Format(L"%5d", 1);
+    EXPECT_EQ(L"    1", str);
+  }
+
+  {
+    CFX_WideString str;
+    str.Format(L"%d", 1);
+    EXPECT_EQ(L"1", str);
+  }
+}
+
+TEST(fxcrt, WideStringFormatPrecision) {
+  {
+    CFX_WideString str;
+    str.Format(L"%.2f", 1.12345);
+    EXPECT_EQ(L"1.12", str);
+  }
+
+  {
+    CFX_WideString str;
+    str.Format(L"%f", 1.12345);
+    EXPECT_EQ(L"1.123450", str);
+  }
+}