diff --git a/http2/hpack/decoder/hpack_string_collector.h b/http2/hpack/decoder/hpack_string_collector.h
new file mode 100644
index 0000000..76be13b
--- /dev/null
+++ b/http2/hpack/decoder/hpack_string_collector.h
@@ -0,0 +1,63 @@
+// Copyright 2016 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.
+
+#ifndef QUICHE_HTTP2_HPACK_DECODER_HPACK_STRING_COLLECTOR_H_
+#define QUICHE_HTTP2_HPACK_DECODER_HPACK_STRING_COLLECTOR_H_
+
+// Supports tests of decoding HPACK strings.
+
+#include <stddef.h>
+
+#include <iosfwd>
+
+#include "testing/gtest/include/gtest/gtest.h"
+#include "net/third_party/quiche/src/http2/hpack/decoder/hpack_string_decoder_listener.h"
+#include "net/third_party/quiche/src/http2/platform/api/http2_string.h"
+#include "net/third_party/quiche/src/http2/platform/api/http2_string_piece.h"
+
+namespace http2 {
+namespace test {
+
+// Records the callbacks associated with a decoding a string; must
+// call Clear() between decoding successive strings.
+struct HpackStringCollector : public HpackStringDecoderListener {
+  enum CollectorState {
+    kGenesis,
+    kStarted,
+    kEnded,
+  };
+
+  HpackStringCollector();
+  HpackStringCollector(const Http2String& str, bool huffman);
+
+  void Clear();
+  bool IsClear() const;
+  bool IsInProgress() const;
+  bool HasEnded() const;
+
+  void OnStringStart(bool huffman, size_t length) override;
+  void OnStringData(const char* data, size_t length) override;
+  void OnStringEnd() override;
+
+  ::testing::AssertionResult Collected(Http2StringPiece str,
+                                       bool is_huffman_encoded) const;
+
+  Http2String ToString() const;
+
+  Http2String s;
+  size_t len;
+  bool huffman_encoded;
+  CollectorState state;
+};
+
+bool operator==(const HpackStringCollector& a, const HpackStringCollector& b);
+
+bool operator!=(const HpackStringCollector& a, const HpackStringCollector& b);
+
+std::ostream& operator<<(std::ostream& out, const HpackStringCollector& v);
+
+}  // namespace test
+}  // namespace http2
+
+#endif  // QUICHE_HTTP2_HPACK_DECODER_HPACK_STRING_COLLECTOR_H_