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diff --git a/src/rocksdb/test_util/testutil.h b/src/rocksdb/test_util/testutil.h
new file mode 100644
index 000000000..3f6b47929
--- /dev/null
+++ b/src/rocksdb/test_util/testutil.h
@@ -0,0 +1,802 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#pragma once
+#include <algorithm>
+#include <deque>
+#include <string>
+#include <vector>
+
+#include "env/composite_env_wrapper.h"
+#include "file/writable_file_writer.h"
+#include "rocksdb/compaction_filter.h"
+#include "rocksdb/env.h"
+#include "rocksdb/iterator.h"
+#include "rocksdb/merge_operator.h"
+#include "rocksdb/options.h"
+#include "rocksdb/slice.h"
+#include "rocksdb/table.h"
+#include "table/block_based/block_based_table_factory.h"
+#include "table/internal_iterator.h"
+#include "table/plain/plain_table_factory.h"
+#include "util/mutexlock.h"
+#include "util/random.h"
+
+namespace ROCKSDB_NAMESPACE {
+class SequentialFile;
+class SequentialFileReader;
+
+namespace test {
+
+extern const uint32_t kDefaultFormatVersion;
+extern const uint32_t kLatestFormatVersion;
+
+// Store in *dst a random string of length "len" and return a Slice that
+// references the generated data.
+extern Slice RandomString(Random* rnd, int len, std::string* dst);
+
+extern std::string RandomHumanReadableString(Random* rnd, int len);
+
+// Return a random key with the specified length that may contain interesting
+// characters (e.g. \x00, \xff, etc.).
+enum RandomKeyType : char { RANDOM, LARGEST, SMALLEST, MIDDLE };
+extern std::string RandomKey(Random* rnd, int len,
+                             RandomKeyType type = RandomKeyType::RANDOM);
+
+// Store in *dst a string of length "len" that will compress to
+// "N*compressed_fraction" bytes and return a Slice that references
+// the generated data.
+extern Slice CompressibleString(Random* rnd, double compressed_fraction,
+                                int len, std::string* dst);
+
+// A wrapper that allows injection of errors.
+class ErrorEnv : public EnvWrapper {
+ public:
+  bool writable_file_error_;
+  int num_writable_file_errors_;
+
+  ErrorEnv() : EnvWrapper(Env::Default()),
+               writable_file_error_(false),
+               num_writable_file_errors_(0) { }
+
+  virtual Status NewWritableFile(const std::string& fname,
+                                 std::unique_ptr<WritableFile>* result,
+                                 const EnvOptions& soptions) override {
+    result->reset();
+    if (writable_file_error_) {
+      ++num_writable_file_errors_;
+      return Status::IOError(fname, "fake error");
+    }
+    return target()->NewWritableFile(fname, result, soptions);
+  }
+};
+
+#ifndef NDEBUG
+// An internal comparator that just forward comparing results from the
+// user comparator in it. Can be used to test entities that have no dependency
+// on internal key structure but consumes InternalKeyComparator, like
+// BlockBasedTable.
+class PlainInternalKeyComparator : public InternalKeyComparator {
+ public:
+  explicit PlainInternalKeyComparator(const Comparator* c)
+      : InternalKeyComparator(c) {}
+
+  virtual ~PlainInternalKeyComparator() {}
+
+  virtual int Compare(const Slice& a, const Slice& b) const override {
+    return user_comparator()->Compare(a, b);
+  }
+};
+#endif
+
+// A test comparator which compare two strings in this way:
+// (1) first compare prefix of 8 bytes in alphabet order,
+// (2) if two strings share the same prefix, sort the other part of the string
+//     in the reverse alphabet order.
+// This helps simulate the case of compounded key of [entity][timestamp] and
+// latest timestamp first.
+class SimpleSuffixReverseComparator : public Comparator {
+ public:
+  SimpleSuffixReverseComparator() {}
+
+  virtual const char* Name() const override {
+    return "SimpleSuffixReverseComparator";
+  }
+
+  virtual int Compare(const Slice& a, const Slice& b) const override {
+    Slice prefix_a = Slice(a.data(), 8);
+    Slice prefix_b = Slice(b.data(), 8);
+    int prefix_comp = prefix_a.compare(prefix_b);
+    if (prefix_comp != 0) {
+      return prefix_comp;
+    } else {
+      Slice suffix_a = Slice(a.data() + 8, a.size() - 8);
+      Slice suffix_b = Slice(b.data() + 8, b.size() - 8);
+      return -(suffix_a.compare(suffix_b));
+    }
+  }
+  virtual void FindShortestSeparator(std::string* /*start*/,
+                                     const Slice& /*limit*/) const override {}
+
+  virtual void FindShortSuccessor(std::string* /*key*/) const override {}
+};
+
+// Returns a user key comparator that can be used for comparing two uint64_t
+// slices. Instead of comparing slices byte-wise, it compares all the 8 bytes
+// at once. Assumes same endian-ness is used though the database's lifetime.
+// Symantics of comparison would differ from Bytewise comparator in little
+// endian machines.
+extern const Comparator* Uint64Comparator();
+
+// Iterator over a vector of keys/values
+class VectorIterator : public InternalIterator {
+ public:
+  explicit VectorIterator(const std::vector<std::string>& keys)
+      : keys_(keys), current_(keys.size()) {
+    std::sort(keys_.begin(), keys_.end());
+    values_.resize(keys.size());
+  }
+
+  VectorIterator(const std::vector<std::string>& keys,
+      const std::vector<std::string>& values)
+    : keys_(keys), values_(values), current_(keys.size()) {
+    assert(keys_.size() == values_.size());
+  }
+
+  virtual bool Valid() const override { return current_ < keys_.size(); }
+
+  virtual void SeekToFirst() override { current_ = 0; }
+  virtual void SeekToLast() override { current_ = keys_.size() - 1; }
+
+  virtual void Seek(const Slice& target) override {
+    current_ = std::lower_bound(keys_.begin(), keys_.end(), target.ToString()) -
+               keys_.begin();
+  }
+
+  virtual void SeekForPrev(const Slice& target) override {
+    current_ = std::upper_bound(keys_.begin(), keys_.end(), target.ToString()) -
+               keys_.begin();
+    if (!Valid()) {
+      SeekToLast();
+    } else {
+      Prev();
+    }
+  }
+
+  virtual void Next() override { current_++; }
+  virtual void Prev() override { current_--; }
+
+  virtual Slice key() const override { return Slice(keys_[current_]); }
+  virtual Slice value() const override { return Slice(values_[current_]); }
+
+  virtual Status status() const override { return Status::OK(); }
+
+  virtual bool IsKeyPinned() const override { return true; }
+  virtual bool IsValuePinned() const override { return true; }
+
+ private:
+  std::vector<std::string> keys_;
+  std::vector<std::string> values_;
+  size_t current_;
+};
+extern WritableFileWriter* GetWritableFileWriter(WritableFile* wf,
+                                                 const std::string& fname);
+
+extern RandomAccessFileReader* GetRandomAccessFileReader(RandomAccessFile* raf);
+
+extern SequentialFileReader* GetSequentialFileReader(SequentialFile* se,
+                                                     const std::string& fname);
+
+class StringSink: public WritableFile {
+ public:
+  std::string contents_;
+
+  explicit StringSink(Slice* reader_contents = nullptr) :
+      WritableFile(),
+      contents_(""),
+      reader_contents_(reader_contents),
+      last_flush_(0) {
+    if (reader_contents_ != nullptr) {
+      *reader_contents_ = Slice(contents_.data(), 0);
+    }
+  }
+
+  const std::string& contents() const { return contents_; }
+
+  virtual Status Truncate(uint64_t size) override {
+    contents_.resize(static_cast<size_t>(size));
+    return Status::OK();
+  }
+  virtual Status Close() override { return Status::OK(); }
+  virtual Status Flush() override {
+    if (reader_contents_ != nullptr) {
+      assert(reader_contents_->size() <= last_flush_);
+      size_t offset = last_flush_ - reader_contents_->size();
+      *reader_contents_ = Slice(
+          contents_.data() + offset,
+          contents_.size() - offset);
+      last_flush_ = contents_.size();
+    }
+
+    return Status::OK();
+  }
+  virtual Status Sync() override { return Status::OK(); }
+  virtual Status Append(const Slice& slice) override {
+    contents_.append(slice.data(), slice.size());
+    return Status::OK();
+  }
+  void Drop(size_t bytes) {
+    if (reader_contents_ != nullptr) {
+      contents_.resize(contents_.size() - bytes);
+      *reader_contents_ = Slice(
+          reader_contents_->data(), reader_contents_->size() - bytes);
+      last_flush_ = contents_.size();
+    }
+  }
+
+ private:
+  Slice* reader_contents_;
+  size_t last_flush_;
+};
+
+// A wrapper around a StringSink to give it a RandomRWFile interface
+class RandomRWStringSink : public RandomRWFile {
+ public:
+  explicit RandomRWStringSink(StringSink* ss) : ss_(ss) {}
+
+  Status Write(uint64_t offset, const Slice& data) override {
+    if (offset + data.size() > ss_->contents_.size()) {
+      ss_->contents_.resize(static_cast<size_t>(offset) + data.size(), '\0');
+    }
+
+    char* pos = const_cast<char*>(ss_->contents_.data() + offset);
+    memcpy(pos, data.data(), data.size());
+    return Status::OK();
+  }
+
+  Status Read(uint64_t offset, size_t n, Slice* result,
+              char* /*scratch*/) const override {
+    *result = Slice(nullptr, 0);
+    if (offset < ss_->contents_.size()) {
+      size_t str_res_sz =
+          std::min(static_cast<size_t>(ss_->contents_.size() - offset), n);
+      *result = Slice(ss_->contents_.data() + offset, str_res_sz);
+    }
+    return Status::OK();
+  }
+
+  Status Flush() override { return Status::OK(); }
+
+  Status Sync() override { return Status::OK(); }
+
+  Status Close() override { return Status::OK(); }
+
+  const std::string& contents() const { return ss_->contents(); }
+
+ private:
+  StringSink* ss_;
+};
+
+// Like StringSink, this writes into a string.  Unlink StringSink, it
+// has some initial content and overwrites it, just like a recycled
+// log file.
+class OverwritingStringSink : public WritableFile {
+ public:
+  explicit OverwritingStringSink(Slice* reader_contents)
+      : WritableFile(),
+        contents_(""),
+        reader_contents_(reader_contents),
+        last_flush_(0) {}
+
+  const std::string& contents() const { return contents_; }
+
+  virtual Status Truncate(uint64_t size) override {
+    contents_.resize(static_cast<size_t>(size));
+    return Status::OK();
+  }
+  virtual Status Close() override { return Status::OK(); }
+  virtual Status Flush() override {
+    if (last_flush_ < contents_.size()) {
+      assert(reader_contents_->size() >= contents_.size());
+      memcpy((char*)reader_contents_->data() + last_flush_,
+             contents_.data() + last_flush_, contents_.size() - last_flush_);
+      last_flush_ = contents_.size();
+    }
+    return Status::OK();
+  }
+  virtual Status Sync() override { return Status::OK(); }
+  virtual Status Append(const Slice& slice) override {
+    contents_.append(slice.data(), slice.size());
+    return Status::OK();
+  }
+  void Drop(size_t bytes) {
+    contents_.resize(contents_.size() - bytes);
+    if (last_flush_ > contents_.size()) last_flush_ = contents_.size();
+  }
+
+ private:
+  std::string contents_;
+  Slice* reader_contents_;
+  size_t last_flush_;
+};
+
+class StringSource: public RandomAccessFile {
+ public:
+  explicit StringSource(const Slice& contents, uint64_t uniq_id = 0,
+                        bool mmap = false)
+      : contents_(contents.data(), contents.size()),
+        uniq_id_(uniq_id),
+        mmap_(mmap),
+        total_reads_(0) {}
+
+  virtual ~StringSource() { }
+
+  uint64_t Size() const { return contents_.size(); }
+
+  virtual Status Read(uint64_t offset, size_t n, Slice* result,
+      char* scratch) const override {
+    total_reads_++;
+    if (offset > contents_.size()) {
+      return Status::InvalidArgument("invalid Read offset");
+    }
+    if (offset + n > contents_.size()) {
+      n = contents_.size() - static_cast<size_t>(offset);
+    }
+    if (!mmap_) {
+      memcpy(scratch, &contents_[static_cast<size_t>(offset)], n);
+      *result = Slice(scratch, n);
+    } else {
+      *result = Slice(&contents_[static_cast<size_t>(offset)], n);
+    }
+    return Status::OK();
+  }
+
+  virtual size_t GetUniqueId(char* id, size_t max_size) const override {
+    if (max_size < 20) {
+      return 0;
+    }
+
+    char* rid = id;
+    rid = EncodeVarint64(rid, uniq_id_);
+    rid = EncodeVarint64(rid, 0);
+    return static_cast<size_t>(rid-id);
+  }
+
+  int total_reads() const { return total_reads_; }
+
+  void set_total_reads(int tr) { total_reads_ = tr; }
+
+ private:
+  std::string contents_;
+  uint64_t uniq_id_;
+  bool mmap_;
+  mutable int total_reads_;
+};
+
+inline StringSink* GetStringSinkFromLegacyWriter(
+    const WritableFileWriter* writer) {
+  LegacyWritableFileWrapper* file =
+      static_cast<LegacyWritableFileWrapper*>(writer->writable_file());
+  return static_cast<StringSink*>(file->target());
+}
+
+class NullLogger : public Logger {
+ public:
+  using Logger::Logv;
+  virtual void Logv(const char* /*format*/, va_list /*ap*/) override {}
+  virtual size_t GetLogFileSize() const override { return 0; }
+};
+
+// Corrupts key by changing the type
+extern void CorruptKeyType(InternalKey* ikey);
+
+extern std::string KeyStr(const std::string& user_key,
+                          const SequenceNumber& seq, const ValueType& t,
+                          bool corrupt = false);
+
+class SleepingBackgroundTask {
+ public:
+  SleepingBackgroundTask()
+      : bg_cv_(&mutex_),
+        should_sleep_(true),
+        done_with_sleep_(false),
+        sleeping_(false) {}
+
+  bool IsSleeping() {
+    MutexLock l(&mutex_);
+    return sleeping_;
+  }
+  void DoSleep() {
+    MutexLock l(&mutex_);
+    sleeping_ = true;
+    bg_cv_.SignalAll();
+    while (should_sleep_) {
+      bg_cv_.Wait();
+    }
+    sleeping_ = false;
+    done_with_sleep_ = true;
+    bg_cv_.SignalAll();
+  }
+  void WaitUntilSleeping() {
+    MutexLock l(&mutex_);
+    while (!sleeping_ || !should_sleep_) {
+      bg_cv_.Wait();
+    }
+  }
+  // Waits for the status to change to sleeping,
+  // otherwise times out.
+  // wait_time is in microseconds.
+  // Returns true when times out, false otherwise.
+  bool TimedWaitUntilSleeping(uint64_t wait_time) {
+    auto abs_time = Env::Default()->NowMicros() + wait_time;
+    MutexLock l(&mutex_);
+    while (!sleeping_ || !should_sleep_) {
+      if (bg_cv_.TimedWait(abs_time)) {
+        return true;
+      }
+    }
+    return false;
+  }
+  void WakeUp() {
+    MutexLock l(&mutex_);
+    should_sleep_ = false;
+    bg_cv_.SignalAll();
+  }
+  void WaitUntilDone() {
+    MutexLock l(&mutex_);
+    while (!done_with_sleep_) {
+      bg_cv_.Wait();
+    }
+  }
+  // Similar to TimedWaitUntilSleeping.
+  // Waits until the task is done.
+  bool TimedWaitUntilDone(uint64_t wait_time) {
+    auto abs_time = Env::Default()->NowMicros() + wait_time;
+    MutexLock l(&mutex_);
+    while (!done_with_sleep_) {
+      if (bg_cv_.TimedWait(abs_time)) {
+        return true;
+      }
+    }
+    return false;
+  }
+  bool WokenUp() {
+    MutexLock l(&mutex_);
+    return should_sleep_ == false;
+  }
+
+  void Reset() {
+    MutexLock l(&mutex_);
+    should_sleep_ = true;
+    done_with_sleep_ = false;
+  }
+
+  static void DoSleepTask(void* arg) {
+    reinterpret_cast<SleepingBackgroundTask*>(arg)->DoSleep();
+  }
+
+ private:
+  port::Mutex mutex_;
+  port::CondVar bg_cv_;  // Signalled when background work finishes
+  bool should_sleep_;
+  bool done_with_sleep_;
+  bool sleeping_;
+};
+
+// Filters merge operands and values that are equal to `num`.
+class FilterNumber : public CompactionFilter {
+ public:
+  explicit FilterNumber(uint64_t num) : num_(num) {}
+
+  std::string last_merge_operand_key() { return last_merge_operand_key_; }
+
+  bool Filter(int /*level*/, const ROCKSDB_NAMESPACE::Slice& /*key*/,
+              const ROCKSDB_NAMESPACE::Slice& value, std::string* /*new_value*/,
+              bool* /*value_changed*/) const override {
+    if (value.size() == sizeof(uint64_t)) {
+      return num_ == DecodeFixed64(value.data());
+    }
+    return true;
+  }
+
+  bool FilterMergeOperand(
+      int /*level*/, const ROCKSDB_NAMESPACE::Slice& key,
+      const ROCKSDB_NAMESPACE::Slice& value) const override {
+    last_merge_operand_key_ = key.ToString();
+    if (value.size() == sizeof(uint64_t)) {
+      return num_ == DecodeFixed64(value.data());
+    }
+    return true;
+  }
+
+  const char* Name() const override { return "FilterBadMergeOperand"; }
+
+ private:
+  mutable std::string last_merge_operand_key_;
+  uint64_t num_;
+};
+
+inline std::string EncodeInt(uint64_t x) {
+  std::string result;
+  PutFixed64(&result, x);
+  return result;
+}
+
+  class SeqStringSource : public SequentialFile {
+   public:
+    SeqStringSource(const std::string& data, std::atomic<int>* read_count)
+        : data_(data), offset_(0), read_count_(read_count) {}
+    ~SeqStringSource() override {}
+    Status Read(size_t n, Slice* result, char* scratch) override {
+      std::string output;
+      if (offset_ < data_.size()) {
+        n = std::min(data_.size() - offset_, n);
+        memcpy(scratch, data_.data() + offset_, n);
+        offset_ += n;
+        *result = Slice(scratch, n);
+      } else {
+        return Status::InvalidArgument(
+            "Attemp to read when it already reached eof.");
+      }
+      (*read_count_)++;
+      return Status::OK();
+    }
+    Status Skip(uint64_t n) override {
+      if (offset_ >= data_.size()) {
+        return Status::InvalidArgument(
+            "Attemp to read when it already reached eof.");
+      }
+      // TODO(yhchiang): Currently doesn't handle the overflow case.
+      offset_ += static_cast<size_t>(n);
+      return Status::OK();
+    }
+
+   private:
+    std::string data_;
+    size_t offset_;
+    std::atomic<int>* read_count_;
+  };
+
+  class StringEnv : public EnvWrapper {
+   public:
+    class StringSink : public WritableFile {
+     public:
+      explicit StringSink(std::string* contents)
+          : WritableFile(), contents_(contents) {}
+      virtual Status Truncate(uint64_t size) override {
+        contents_->resize(static_cast<size_t>(size));
+        return Status::OK();
+      }
+      virtual Status Close() override { return Status::OK(); }
+      virtual Status Flush() override { return Status::OK(); }
+      virtual Status Sync() override { return Status::OK(); }
+      virtual Status Append(const Slice& slice) override {
+        contents_->append(slice.data(), slice.size());
+        return Status::OK();
+      }
+
+     private:
+      std::string* contents_;
+    };
+
+    explicit StringEnv(Env* t) : EnvWrapper(t) {}
+    ~StringEnv() override {}
+
+    const std::string& GetContent(const std::string& f) { return files_[f]; }
+
+    const Status WriteToNewFile(const std::string& file_name,
+                                const std::string& content) {
+      std::unique_ptr<WritableFile> r;
+      auto s = NewWritableFile(file_name, &r, EnvOptions());
+      if (!s.ok()) {
+        return s;
+      }
+      r->Append(content);
+      r->Flush();
+      r->Close();
+      assert(files_[file_name] == content);
+      return Status::OK();
+    }
+
+    // The following text is boilerplate that forwards all methods to target()
+    Status NewSequentialFile(const std::string& f,
+                             std::unique_ptr<SequentialFile>* r,
+                             const EnvOptions& /*options*/) override {
+      auto iter = files_.find(f);
+      if (iter == files_.end()) {
+        return Status::NotFound("The specified file does not exist", f);
+      }
+      r->reset(new SeqStringSource(iter->second, &num_seq_file_read_));
+      return Status::OK();
+    }
+    Status NewRandomAccessFile(const std::string& /*f*/,
+                               std::unique_ptr<RandomAccessFile>* /*r*/,
+                               const EnvOptions& /*options*/) override {
+      return Status::NotSupported();
+    }
+    Status NewWritableFile(const std::string& f,
+                           std::unique_ptr<WritableFile>* r,
+                           const EnvOptions& /*options*/) override {
+      auto iter = files_.find(f);
+      if (iter != files_.end()) {
+        return Status::IOError("The specified file already exists", f);
+      }
+      r->reset(new StringSink(&files_[f]));
+      return Status::OK();
+    }
+    virtual Status NewDirectory(
+        const std::string& /*name*/,
+        std::unique_ptr<Directory>* /*result*/) override {
+      return Status::NotSupported();
+    }
+    Status FileExists(const std::string& f) override {
+      if (files_.find(f) == files_.end()) {
+        return Status::NotFound();
+      }
+      return Status::OK();
+    }
+    Status GetChildren(const std::string& /*dir*/,
+                       std::vector<std::string>* /*r*/) override {
+      return Status::NotSupported();
+    }
+    Status DeleteFile(const std::string& f) override {
+      files_.erase(f);
+      return Status::OK();
+    }
+    Status CreateDir(const std::string& /*d*/) override {
+      return Status::NotSupported();
+    }
+    Status CreateDirIfMissing(const std::string& /*d*/) override {
+      return Status::NotSupported();
+    }
+    Status DeleteDir(const std::string& /*d*/) override {
+      return Status::NotSupported();
+    }
+    Status GetFileSize(const std::string& f, uint64_t* s) override {
+      auto iter = files_.find(f);
+      if (iter == files_.end()) {
+        return Status::NotFound("The specified file does not exist:", f);
+      }
+      *s = iter->second.size();
+      return Status::OK();
+    }
+
+    Status GetFileModificationTime(const std::string& /*fname*/,
+                                   uint64_t* /*file_mtime*/) override {
+      return Status::NotSupported();
+    }
+
+    Status RenameFile(const std::string& /*s*/,
+                      const std::string& /*t*/) override {
+      return Status::NotSupported();
+    }
+
+    Status LinkFile(const std::string& /*s*/,
+                    const std::string& /*t*/) override {
+      return Status::NotSupported();
+    }
+
+    Status LockFile(const std::string& /*f*/, FileLock** /*l*/) override {
+      return Status::NotSupported();
+    }
+
+    Status UnlockFile(FileLock* /*l*/) override {
+      return Status::NotSupported();
+    }
+
+    std::atomic<int> num_seq_file_read_;
+
+   protected:
+    std::unordered_map<std::string, std::string> files_;
+  };
+
+// Randomly initialize the given DBOptions
+void RandomInitDBOptions(DBOptions* db_opt, Random* rnd);
+
+// Randomly initialize the given ColumnFamilyOptions
+// Note that the caller is responsible for releasing non-null
+// cf_opt->compaction_filter.
+void RandomInitCFOptions(ColumnFamilyOptions* cf_opt, DBOptions&, Random* rnd);
+
+// A dummy merge operator which can change its name
+class ChanglingMergeOperator : public MergeOperator {
+ public:
+  explicit ChanglingMergeOperator(const std::string& name)
+      : name_(name + "MergeOperator") {}
+  ~ChanglingMergeOperator() {}
+
+  void SetName(const std::string& name) { name_ = name; }
+
+  virtual bool FullMergeV2(const MergeOperationInput& /*merge_in*/,
+                           MergeOperationOutput* /*merge_out*/) const override {
+    return false;
+  }
+  virtual bool PartialMergeMulti(const Slice& /*key*/,
+                                 const std::deque<Slice>& /*operand_list*/,
+                                 std::string* /*new_value*/,
+                                 Logger* /*logger*/) const override {
+    return false;
+  }
+  virtual const char* Name() const override { return name_.c_str(); }
+
+ protected:
+  std::string name_;
+};
+
+// Returns a dummy merge operator with random name.
+MergeOperator* RandomMergeOperator(Random* rnd);
+
+// A dummy compaction filter which can change its name
+class ChanglingCompactionFilter : public CompactionFilter {
+ public:
+  explicit ChanglingCompactionFilter(const std::string& name)
+      : name_(name + "CompactionFilter") {}
+  ~ChanglingCompactionFilter() {}
+
+  void SetName(const std::string& name) { name_ = name; }
+
+  bool Filter(int /*level*/, const Slice& /*key*/,
+              const Slice& /*existing_value*/, std::string* /*new_value*/,
+              bool* /*value_changed*/) const override {
+    return false;
+  }
+
+  const char* Name() const override { return name_.c_str(); }
+
+ private:
+  std::string name_;
+};
+
+// Returns a dummy compaction filter with a random name.
+CompactionFilter* RandomCompactionFilter(Random* rnd);
+
+// A dummy compaction filter factory which can change its name
+class ChanglingCompactionFilterFactory : public CompactionFilterFactory {
+ public:
+  explicit ChanglingCompactionFilterFactory(const std::string& name)
+      : name_(name + "CompactionFilterFactory") {}
+  ~ChanglingCompactionFilterFactory() {}
+
+  void SetName(const std::string& name) { name_ = name; }
+
+  std::unique_ptr<CompactionFilter> CreateCompactionFilter(
+      const CompactionFilter::Context& /*context*/) override {
+    return std::unique_ptr<CompactionFilter>();
+  }
+
+  // Returns a name that identifies this compaction filter factory.
+  const char* Name() const override { return name_.c_str(); }
+
+ protected:
+  std::string name_;
+};
+
+CompressionType RandomCompressionType(Random* rnd);
+
+void RandomCompressionTypeVector(const size_t count,
+                                 std::vector<CompressionType>* types,
+                                 Random* rnd);
+
+CompactionFilterFactory* RandomCompactionFilterFactory(Random* rnd);
+
+const SliceTransform* RandomSliceTransform(Random* rnd, int pre_defined = -1);
+
+TableFactory* RandomTableFactory(Random* rnd, int pre_defined = -1);
+
+std::string RandomName(Random* rnd, const size_t len);
+
+Status DestroyDir(Env* env, const std::string& dir);
+
+bool IsDirectIOSupported(Env* env, const std::string& dir);
+
+// Return the number of lines where a given pattern was found in a file.
+size_t GetLinesCount(const std::string& fname, const std::string& pattern);
+
+}  // namespace test
+}  // namespace ROCKSDB_NAMESPACE