diff --git a/tests/image-fuzzer/runner.py b/tests/image-fuzzer/runner.py
new file mode 100755
index 0000000..58079d3
--- /dev/null
+++ b/tests/image-fuzzer/runner.py
@@ -0,0 +1,405 @@
+#!/usr/bin/env python
+
+# Tool for running fuzz tests
+#
+# Copyright (C) 2014 Maria Kustova <maria.k@catit.be>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+import sys
+import os
+import signal
+import subprocess
+import random
+import shutil
+from itertools import count
+import getopt
+import StringIO
+import resource
+
+try:
+    import json
+except ImportError:
+    try:
+        import simplejson as json
+    except ImportError:
+        print >>sys.stderr, \
+            "Warning: Module for JSON processing is not found.\n" \
+            "'--config' and '--command' options are not supported."
+
+# Backing file sizes in MB
+MAX_BACKING_FILE_SIZE = 10
+MIN_BACKING_FILE_SIZE = 1
+
+
+def multilog(msg, *output):
+    """ Write an object to all of specified file descriptors."""
+    for fd in output:
+        fd.write(msg)
+        fd.flush()
+
+
+def str_signal(sig):
+    """ Convert a numeric value of a system signal to the string one
+    defined by the current operational system.
+    """
+    for k, v in signal.__dict__.items():
+        if v == sig:
+            return k
+
+
+def run_app(fd, q_args):
+    """Start an application with specified arguments and return its exit code
+    or kill signal depending on the result of execution.
+    """
+    devnull = open('/dev/null', 'r+')
+    process = subprocess.Popen(q_args, stdin=devnull,
+                               stdout=subprocess.PIPE,
+                               stderr=subprocess.PIPE)
+    out, err = process.communicate()
+    fd.write(out)
+    fd.write(err)
+    return process.returncode
+
+
+class TestException(Exception):
+    """Exception for errors risen by TestEnv objects."""
+    pass
+
+
+class TestEnv(object):
+
+    """Test object.
+
+    The class sets up test environment, generates backing and test images
+    and executes application under tests with specified arguments and a test
+    image provided.
+
+    All logs are collected.
+
+    The summary log will contain short descriptions and statuses of tests in
+    a run.
+
+    The test log will include application (e.g. 'qemu-img') logs besides info
+    sent to the summary log.
+    """
+
+    def __init__(self, test_id, seed, work_dir, run_log,
+                 cleanup=True, log_all=False):
+        """Set test environment in a specified work directory.
+
+        Path to qemu-img and qemu-io will be retrieved from 'QEMU_IMG' and
+        'QEMU_IO' environment variables.
+        """
+        if seed is not None:
+            self.seed = seed
+        else:
+            self.seed = str(random.randint(0, sys.maxint))
+        random.seed(self.seed)
+
+        self.init_path = os.getcwd()
+        self.work_dir = work_dir
+        self.current_dir = os.path.join(work_dir, 'test-' + test_id)
+        self.qemu_img = os.environ.get('QEMU_IMG', 'qemu-img')\
+                                  .strip().split(' ')
+        self.qemu_io = os.environ.get('QEMU_IO', 'qemu-io').strip().split(' ')
+        self.commands = [['qemu-img', 'check', '-f', 'qcow2', '$test_img'],
+                         ['qemu-img', 'info', '-f', 'qcow2', '$test_img'],
+                         ['qemu-io', '$test_img', '-c', 'read $off $len'],
+                         ['qemu-io', '$test_img', '-c', 'write $off $len'],
+                         ['qemu-io', '$test_img', '-c',
+                          'aio_read $off $len'],
+                         ['qemu-io', '$test_img', '-c',
+                          'aio_write $off $len'],
+                         ['qemu-io', '$test_img', '-c', 'flush'],
+                         ['qemu-io', '$test_img', '-c',
+                          'discard $off $len'],
+                         ['qemu-io', '$test_img', '-c',
+                          'truncate $off']]
+        for fmt in ['raw', 'vmdk', 'vdi', 'cow', 'qcow2', 'file',
+                    'qed', 'vpc']:
+            self.commands.append(
+                ['qemu-img', 'convert', '-f', 'qcow2', '-O', fmt,
+                 '$test_img', 'converted_image.' + fmt])
+
+        try:
+            os.makedirs(self.current_dir)
+        except OSError, e:
+            print >>sys.stderr, \
+                "Error: The working directory '%s' cannot be used. Reason: %s"\
+                % (self.work_dir, e[1])
+            raise TestException
+        self.log = open(os.path.join(self.current_dir, "test.log"), "w")
+        self.parent_log = open(run_log, "a")
+        self.failed = False
+        self.cleanup = cleanup
+        self.log_all = log_all
+
+    def _create_backing_file(self):
+        """Create a backing file in the current directory.
+
+        Return a tuple of a backing file name and format.
+
+        Format of a backing file is randomly chosen from all formats supported
+        by 'qemu-img create'.
+        """
+        # All formats supported by the 'qemu-img create' command.
+        backing_file_fmt = random.choice(['raw', 'vmdk', 'vdi', 'cow', 'qcow2',
+                                          'file', 'qed', 'vpc'])
+        backing_file_name = 'backing_img.' + backing_file_fmt
+        backing_file_size = random.randint(MIN_BACKING_FILE_SIZE,
+                                           MAX_BACKING_FILE_SIZE) * (1 << 20)
+        cmd = self.qemu_img + ['create', '-f', backing_file_fmt,
+                               backing_file_name, str(backing_file_size)]
+        temp_log = StringIO.StringIO()
+        retcode = run_app(temp_log, cmd)
+        if retcode == 0:
+            temp_log.close()
+            return (backing_file_name, backing_file_fmt)
+        else:
+            multilog("Warning: The %s backing file was not created.\n\n"
+                     % backing_file_fmt, sys.stderr, self.log, self.parent_log)
+            self.log.write("Log for the failure:\n" + temp_log.getvalue() +
+                           '\n\n')
+            temp_log.close()
+            return (None, None)
+
+    def execute(self, input_commands=None, fuzz_config=None):
+        """ Execute a test.
+
+        The method creates backing and test images, runs test app and analyzes
+        its exit status. If the application was killed by a signal, the test
+        is marked as failed.
+        """
+        if input_commands is None:
+            commands = self.commands
+        else:
+            commands = input_commands
+
+        os.chdir(self.current_dir)
+        backing_file_name, backing_file_fmt = self._create_backing_file()
+        img_size = image_generator.create_image('test.img',
+                                                backing_file_name,
+                                                backing_file_fmt,
+                                                fuzz_config)
+        for item in commands:
+            shutil.copy('test.img', 'copy.img')
+            # 'off' and 'len' are multiple of the sector size
+            sector_size = 512
+            start = random.randrange(0, img_size + 1, sector_size)
+            end = random.randrange(start, img_size + 1, sector_size)
+
+            if item[0] == 'qemu-img':
+                current_cmd = list(self.qemu_img)
+            elif item[0] == 'qemu-io':
+                current_cmd = list(self.qemu_io)
+            else:
+                multilog("Warning: test command '%s' is not defined.\n" \
+                         % item[0], sys.stderr, self.log, self.parent_log)
+                continue
+            # Replace all placeholders with their real values
+            for v in item[1:]:
+                c = (v
+                     .replace('$test_img', 'copy.img')
+                     .replace('$off', str(start))
+                     .replace('$len', str(end - start)))
+                current_cmd.append(c)
+
+            # Log string with the test header
+            test_summary = "Seed: %s\nCommand: %s\nTest directory: %s\n" \
+                           "Backing file: %s\n" \
+                           % (self.seed, " ".join(current_cmd),
+                              self.current_dir, backing_file_name)
+
+            temp_log = StringIO.StringIO()
+            try:
+                retcode = run_app(temp_log, current_cmd)
+            except OSError, e:
+                multilog(test_summary + "Error: Start of '%s' failed. " \
+                         "Reason: %s\n\n" % (os.path.basename(
+                             current_cmd[0]), e[1]),
+                         sys.stderr, self.log, self.parent_log)
+                raise TestException
+
+            if retcode < 0:
+                self.log.write(temp_log.getvalue())
+                multilog(test_summary + "FAIL: Test terminated by signal " +
+                         "%s\n\n" % str_signal(-retcode), sys.stderr, self.log,
+                         self.parent_log)
+                self.failed = True
+            else:
+                if self.log_all:
+                    self.log.write(temp_log.getvalue())
+                    multilog(test_summary + "PASS: Application exited with" +
+                             " the code '%d'\n\n" % retcode, sys.stdout,
+                             self.log, self.parent_log)
+            temp_log.close()
+            os.remove('copy.img')
+
+    def finish(self):
+        """Restore the test environment after a test execution."""
+        self.log.close()
+        self.parent_log.close()
+        os.chdir(self.init_path)
+        if self.cleanup and not self.failed:
+            shutil.rmtree(self.current_dir)
+
+if __name__ == '__main__':
+
+    def usage():
+        print """
+        Usage: runner.py [OPTION...] TEST_DIR IMG_GENERATOR
+
+        Set up test environment in TEST_DIR and run a test in it. A module for
+        test image generation should be specified via IMG_GENERATOR.
+        Example:
+        runner.py -c '[["qemu-img", "info", "$test_img"]]' /tmp/test qcow2
+
+        Optional arguments:
+          -h, --help                    display this help and exit
+          -c, --command=JSON            run tests for all commands specified in
+                                        the JSON array
+          -s, --seed=STRING             seed for a test image generation,
+                                        by default will be generated randomly
+          --config=JSON                 take fuzzer configuration from the JSON
+                                        array
+          -k, --keep_passed             don't remove folders of passed tests
+          -v, --verbose                 log information about passed tests
+
+        JSON:
+
+        '--command' accepts a JSON array of commands. Each command presents
+        an application under test with all its paramaters as a list of strings,
+        e.g.
+          ["qemu-io", "$test_img", "-c", "write $off $len"]
+
+        Supported application aliases: 'qemu-img' and 'qemu-io'.
+        Supported argument aliases: $test_img for the fuzzed image, $off
+        for an offset, $len for length.
+
+        Values for $off and $len will be generated based on the virtual disk
+        size of the fuzzed image
+        Paths to 'qemu-img' and 'qemu-io' are retrevied from 'QEMU_IMG' and
+        'QEMU_IO' environment variables
+
+        '--config' accepts a JSON array of fields to be fuzzed, e.g.
+          '[["header"], ["header", "version"]]'
+        Each of the list elements can consist of a complex image element only
+        as ["header"] or ["feature_name_table"] or an exact field as
+        ["header", "version"]. In the first case random portion of the element
+        fields will be fuzzed, in the second one the specified field will be
+        fuzzed always.
+
+        If '--config' argument is specified, fields not listed in
+        the configuration array will not be fuzzed.
+        """
+
+    def run_test(test_id, seed, work_dir, run_log, cleanup, log_all,
+                 command, fuzz_config):
+        """Setup environment for one test and execute this test."""
+        try:
+            test = TestEnv(test_id, seed, work_dir, run_log, cleanup,
+                           log_all)
+        except TestException:
+            sys.exit(1)
+
+        # Python 2.4 doesn't support 'finally' and 'except' in the same 'try'
+        # block
+        try:
+            try:
+                test.execute(command, fuzz_config)
+            except TestException:
+                sys.exit(1)
+        finally:
+            test.finish()
+
+    try:
+        opts, args = getopt.gnu_getopt(sys.argv[1:], 'c:hs:kv',
+                                       ['command=', 'help', 'seed=', 'config=',
+                                        'keep_passed', 'verbose'])
+    except getopt.error, e:
+        print >>sys.stderr, \
+            "Error: %s\n\nTry 'runner.py --help' for more information" % e
+        sys.exit(1)
+
+    command = None
+    cleanup = True
+    log_all = False
+    seed = None
+    config = None
+    for opt, arg in opts:
+        if opt in ('-h', '--help'):
+            usage()
+            sys.exit()
+        elif opt in ('-c', '--command'):
+            try:
+                command = json.loads(arg)
+            except (TypeError, ValueError, NameError), e:
+                print >>sys.stderr, \
+                    "Error: JSON array of test commands cannot be loaded.\n" \
+                    "Reason: %s" % e
+                sys.exit(1)
+        elif opt in ('-k', '--keep_passed'):
+            cleanup = False
+        elif opt in ('-v', '--verbose'):
+            log_all = True
+        elif opt in ('-s', '--seed'):
+            seed = arg
+        elif opt == '--config':
+            try:
+                config = json.loads(arg)
+            except (TypeError, ValueError, NameError), e:
+                print >>sys.stderr, \
+                    "Error: JSON array with the fuzzer configuration cannot" \
+                    " be loaded\nReason: %s" % e
+                sys.exit(1)
+
+    if not len(args) == 2:
+        print >>sys.stderr, \
+            "Expected two parameters\nTry 'runner.py --help'" \
+            " for more information."
+        sys.exit(1)
+
+    work_dir = os.path.realpath(args[0])
+    # run_log is created in 'main', because multiple tests are expected to
+    # log in it
+    run_log = os.path.join(work_dir, 'run.log')
+
+    # Add the path to the image generator module to sys.path
+    sys.path.append(os.path.realpath(os.path.dirname(args[1])))
+    # Remove a script extension from image generator module if any
+    generator_name = os.path.splitext(os.path.basename(args[1]))[0]
+
+    try:
+        image_generator = __import__(generator_name)
+    except ImportError, e:
+        print >>sys.stderr, \
+            "Error: The image generator '%s' cannot be imported.\n" \
+            "Reason: %s" % (generator_name, e)
+        sys.exit(1)
+
+    # Enable core dumps
+    resource.setrlimit(resource.RLIMIT_CORE, (-1, -1))
+    # If a seed is specified, only one test will be executed.
+    # Otherwise runner will terminate after a keyboard interruption
+    for test_id in count(1):
+        try:
+            run_test(str(test_id), seed, work_dir, run_log, cleanup,
+                     log_all, command, config)
+        except (KeyboardInterrupt, SystemExit):
+            sys.exit(1)
+
+        if seed is not None:
+            break