Slight API change enabling opting out from null termination in String::Write*().

test/cctest/test-api.cc

Index: test/cctest/test-api.cc
diff --git a/test/cctest/test-api.cc b/test/cctest/test-api.cc
index e206bb9ac366f3ed1ade216406cf9914410b6ca0..cd3e0873032173392c77122a95282fe08380de6e 100644
--- a/test/cctest/test-api.cc
+++ b/test/cctest/test-api.cc
@@ -5296,6 +5296,40 @@ THREADED_TEST(StringWrite) {
   CHECK_EQ(0, strncmp("d\1", buf, 2));
   uint16_t answer7[] = {'d', 0x101};
   CHECK_EQ(0, StrNCmp16(answer7, wbuf, 2));
+
+  memset(wbuf, 0x1, sizeof(wbuf));
+  wbuf[5] = 'X';
+  len = str->Write(wbuf, 0, 6, String::WRITE_NO_NULL_TERMINATION);
+  CHECK_EQ(5, len);
+  CHECK_EQ('X', wbuf[5]);
+  uint16_t answer8a[] = {'a', 'b', 'c', 'd', 'e'};
+  uint16_t answer8b[] = {'a', 'b', 'c', 'd', 'e', '\0'};
+  CHECK_EQ(0, StrNCmp16(answer8a, wbuf, 5));
+  CHECK_NE(0, StrCmp16(answer8b, wbuf));
+  wbuf[5] = '\0';
+  CHECK_EQ(0, StrCmp16(answer8b, wbuf));
+
+  memset(buf, 0x1, sizeof(buf));
+  buf[5] = 'X';
+  len = str->WriteAscii(buf, 0, 6, String::WRITE_NO_NULL_TERMINATION);
+  CHECK_EQ(5, len);
+  CHECK_EQ('X', buf[5]);
+  CHECK_EQ(0, strncmp("abcde", buf, 5));
+  CHECK_NE(0, strcmp("abcde", buf));
+  buf[5] = '\0';
+  CHECK_EQ(0, strcmp("abcde", buf));
+
+  memset(utf8buf, 0x1, sizeof(utf8buf));
+  utf8buf[8] = 'X';
+  len = str2->WriteUtf8(utf8buf, sizeof(utf8buf), &charlen,
+                        String::WRITE_NO_NULL_TERMINATION);
+  CHECK_EQ(8, len);
+  CHECK_EQ('X', utf8buf[8]);
+  CHECK_EQ(5, charlen);
+  CHECK_EQ(0, strncmp(utf8buf, "abc\303\260\342\230\203", 8));
+  CHECK_NE(0, strcmp(utf8buf, "abc\303\260\342\230\203"));
+  utf8buf[8] = '\0';
+  CHECK_EQ(0, strcmp(utf8buf, "abc\303\260\342\230\203"));
 }