Add a common function to generate a long string to test.

tests/utils.h

@@ -103,6 +103,27 @@ inline bool fileEqual(const string &filename1, const string &filename2)
   return stream1.good() == stream2.good();
 }
 
+#ifdef TAGLIB_STRING_H
+
+namespace TagLib {
+
+  inline String longText(size_t length, bool random = false)
+  {
+    const wchar_t chars[] = L"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz_";
+
+    std::wstring text(length, L'X');
+
+    if(random) {
+      for(size_t i = 0; i < length; ++i)
+        text[i] = chars[rand() % 53];
+    }
+
+    return String(text);
+  }
+}
+
+#endif
+
 class ScopedFileCopy
 {
 public: