Introducing a net::GenerateMimeMultipartBoundary helper.

net/base/mime_util_unittest.cc

 // Copyright (c) 2012 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 "base/strings/string_split.h"
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
 #include "net/base/mime_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 255 matching lines @@
 #else
       if (extensions[j] == tests[i].contained_result)
         found = true;
 #endif
     }
     ASSERT_TRUE(found) << "Must find at least the contained result within "
                        << tests[i].mime_type;
   }
 }
 
+TEST(MimeUtilTest, TestGenerateMimeMultipartBoundary) {
+  std::string boundary1 = GenerateMimeMultipartBoundary();
+  std::string boundary2 = GenerateMimeMultipartBoundary();
+
+  // RFC 1341 says: the boundary parameter [...] consists of 1 to 70 characters.
+  EXPECT_GE(70u, boundary1.size());
+  EXPECT_GE(70u, boundary2.size());
+
+  // RFC 1341 asks to: exercise care to choose a unique boundary.
+  EXPECT_NE(boundary1, boundary2);
+  ASSERT_LE(16u, boundary1.size());
+  ASSERT_LE(16u, boundary2.size());
+
+  // Asserts below are not RFC 1341 requirements, but are here
+  // to improve readability of generated MIME documents and to
+  // try to preserve some aspects of the old boundary generation code.
+  EXPECT_EQ("--", boundary1.substr(0, 2));
+  EXPECT_EQ("--", boundary2.substr(0, 2));
+  EXPECT_NE(std::string::npos, boundary1.find("MultipartBoundary"));
+  EXPECT_NE(std::string::npos, boundary2.find("MultipartBoundary"));
+  EXPECT_EQ("--", boundary1.substr(boundary1.size() - 2, 2));
+  EXPECT_EQ("--", boundary2.substr(boundary2.size() - 2, 2));
+}
 
 TEST(MimeUtilTest, TestAddMultipartValueForUpload) {
   const char ref_output[] =
       "--boundary\r\nContent-Disposition: form-data;"
       " name=\"value name\"\r\nContent-Type: content type"
       "\r\n\r\nvalue\r\n"
       "--boundary\r\nContent-Disposition: form-data;"
       " name=\"value name\"\r\n\r\nvalue\r\n"
       "--boundary--\r\n";
   std::string post_data;
   AddMultipartValueForUpload("value name", "value", "boundary",
                              "content type", &post_data);
   AddMultipartValueForUpload("value name", "value", "boundary",
                              "", &post_data);
   AddMultipartFinalDelimiterForUpload("boundary", &post_data);
   EXPECT_STREQ(ref_output, post_data.c_str());
 }
 
 }  // namespace net