diff --git a/build-cp.sh b/build-cp.sh
index 7da4aae..675243a 100755
--- a/build-cp.sh
+++ b/build-cp.sh
@@ -8,7 +8,7 @@ make -C circuitpython/mpy-cross -j$nproc
 make -C circuitpython/ports/unix -j$nproc deplibs
 make -C circuitpython/ports/unix -j$nproc
 
-if ! env MICROPY_MICROPYTHON=circuitpython/ports/unix/micropython circuitpython/tests/run-tests -d tests; then
+if ! env MICROPY_MICROPYTHON=circuitpython/ports/unix/micropython ./run-tests -d tests; then
     for exp in *.exp; do
         testbase=$(basename $exp .exp);
         echo -e "\nFAILURE $testbase";
diff --git a/build.sh b/build.sh
index f43b2fb..ecc541a 100755
--- a/build.sh
+++ b/build.sh
@@ -8,7 +8,7 @@ make -C micropython/mpy-cross -j$(nproc)
 make -C micropython/ports/unix -j$(nproc) deplibs
 make -C micropython/ports/unix -j$(nproc) USER_C_MODULES="${HERE}" DEBUG=1 STRIP=:
 
-if ! env MICROPY_MICROPYTHON=micropython/ports/unix/micropython micropython/tests/run-tests -d tests; then
+if ! env MICROPY_MICROPYTHON=micropython/ports/unix/micropython ./run-tests -d tests; then
     for exp in *.exp; do
         testbase=$(basename $exp .exp);
         echo -e "\nFAILURE $testbase";
diff --git a/run-tests b/run-tests
new file mode 100755
index 0000000..880b13f
--- /dev/null
+++ b/run-tests
@@ -0,0 +1,570 @@
+#! /usr/bin/env python3
+
+import os
+import subprocess
+import sys
+import platform
+import argparse
+import re
+import threading
+import multiprocessing
+from multiprocessing.pool import ThreadPool
+from glob import glob
+
+if os.name == 'nt':
+    MICROPYTHON = os.getenv('MICROPY_MICROPYTHON', 'micropython/ports/windows/micropython.exe')
+else:
+    MICROPYTHON = os.getenv('MICROPY_MICROPYTHON', 'micropython/ports/unix/micropython')
+
+# mpy-cross is only needed if --via-mpy command-line arg is passed
+MPYCROSS = os.getenv('MICROPY_MPYCROSS', '../mpy-cross/mpy-cross')
+
+# Set PYTHONIOENCODING so that CPython will use utf-8 on systems which set another encoding in the locale
+os.environ['PYTHONIOENCODING'] = 'utf-8'
+
+def rm_f(fname):
+    if os.path.exists(fname):
+        os.remove(fname)
+
+
+# unescape wanted regex chars and escape unwanted ones
+def convert_regex_escapes(line):
+    cs = []
+    escape = False
+    for c in str(line, 'utf8'):
+        if escape:
+            escape = False
+            cs.append(c)
+        elif c == '\\':
+            escape = True
+        elif c in ('(', ')', '[', ']', '{', '}', '.', '*', '+', '^', '$'):
+            cs.append('\\' + c)
+        else:
+            cs.append(c)
+    # accept carriage-return(s) before final newline
+    if cs[-1] == '\n':
+        cs[-1] = '\r*\n'
+    return bytes(''.join(cs), 'utf8')
+
+
+def run_micropython(pyb, args, test_file, is_special=False):
+    special_tests = (
+        'micropython/meminfo.py', 'basics/bytes_compare3.py',
+        'basics/builtin_help.py', 'thread/thread_exc2.py',
+    )
+    had_crash = False
+    if pyb is None:
+        # run on PC
+        if test_file.startswith(('cmdline/', 'feature_check/')) or test_file in special_tests:
+            # special handling for tests of the unix cmdline program
+            is_special = True
+
+        if is_special:
+            # check for any cmdline options needed for this test
+            args = [MICROPYTHON]
+            with open(test_file, 'rb') as f:
+                line = f.readline()
+                if line.startswith(b'# cmdline:'):
+                    # subprocess.check_output on Windows only accepts strings, not bytes
+                    args += [str(c, 'utf-8') for c in line[10:].strip().split()]
+
+            # run the test, possibly with redirected input
+            try:
+                if 'repl_' in test_file:
+                    # Need to use a PTY to test command line editing
+                    try:
+                        import pty
+                    except ImportError:
+                        # in case pty module is not available, like on Windows
+                        return b'SKIP\n'
+                    import select
+
+                    def get(required=False):
+                        rv = b''
+                        while True:
+                            ready = select.select([emulator], [], [], 0.02)
+                            if ready[0] == [emulator]:
+                                rv += os.read(emulator, 1024)
+                            else:
+                                if not required or rv:
+                                    return rv
+
+                    def send_get(what):
+                        os.write(emulator, what)
+                        return get()
+
+                    with open(test_file, 'rb') as f:
+                        # instead of: output_mupy = subprocess.check_output(args, stdin=f)
+                        # openpty returns two read/write file descriptors.  The first one is
+                        # used by the program which provides the virtual
+                        # terminal service, and the second one is used by the
+                        # subprogram which requires a tty to work.
+                        emulator, subterminal = pty.openpty()
+                        p = subprocess.Popen(args, stdin=subterminal, stdout=subterminal,
+                                             stderr=subprocess.STDOUT, bufsize=0)
+                        banner = get(True)
+                        output_mupy = banner + b''.join(send_get(line) for line in f)
+                        send_get(b'\x04') # exit the REPL, so coverage info is saved
+                        p.kill()
+                        os.close(emulator)
+                        os.close(subterminal)
+                else:
+                    output_mupy = subprocess.check_output(args + [test_file], stderr=subprocess.STDOUT)
+            except subprocess.CalledProcessError:
+                return b'CRASH'
+
+        else:
+            # a standard test run on PC
+
+            # create system command
+            cmdlist = [MICROPYTHON, '-X', 'emit=' + args.emit]
+            if args.heapsize is not None:
+                cmdlist.extend(['-X', 'heapsize=' + args.heapsize])
+
+            # if running via .mpy, first compile the .py file
+            if args.via_mpy:
+                subprocess.check_output([MPYCROSS, '-mcache-lookup-bc', '-o', 'mpytest.mpy', test_file])
+                cmdlist.extend(['-m', 'mpytest'])
+            else:
+                cmdlist.append(test_file)
+
+            # run the actual test
+            e = {"MICROPYPATH": os.getcwd() + ":", "LANG": "en_US.UTF-8"}
+            p = subprocess.Popen(cmdlist, env=e, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
+            output_mupy = b''
+            while p.poll() is None:
+                output_mupy += p.stdout.read()
+            output_mupy += p.stdout.read()
+            if p.returncode != 0:
+                output_mupy = b'CRASH'
+
+            # clean up if we had an intermediate .mpy file
+            if args.via_mpy:
+                rm_f('mpytest.mpy')
+
+    else:
+        # run on pyboard
+        import pyboard
+        pyb.enter_raw_repl()
+        try:
+            output_mupy = pyb.execfile(test_file)
+        except pyboard.PyboardError:
+            had_crash = True
+            output_mupy = b'CRASH'
+
+    # canonical form for all ports/platforms is to use \n for end-of-line
+    output_mupy = output_mupy.replace(b'\r\n', b'\n')
+
+    # don't try to convert the output if we should skip this test
+    if had_crash or output_mupy in (b'SKIP\n', b'CRASH'):
+        return output_mupy
+
+    if is_special or test_file in special_tests:
+        # convert parts of the output that are not stable across runs
+        with open(test_file + '.exp', 'rb') as f:
+            lines_exp = []
+            for line in f.readlines():
+                if line == b'########\n':
+                    line = (line,)
+                else:
+                    line = (line, re.compile(convert_regex_escapes(line)))
+                lines_exp.append(line)
+        lines_mupy = [line + b'\n' for line in output_mupy.split(b'\n')]
+        if output_mupy.endswith(b'\n'):
+            lines_mupy = lines_mupy[:-1] # remove erroneous last empty line
+        i_mupy = 0
+        for i in range(len(lines_exp)):
+            if lines_exp[i][0] == b'########\n':
+                # 8x #'s means match 0 or more whole lines
+                line_exp = lines_exp[i + 1]
+                skip = 0
+                while i_mupy + skip < len(lines_mupy) and not line_exp[1].match(lines_mupy[i_mupy + skip]):
+                    skip += 1
+                if i_mupy + skip >= len(lines_mupy):
+                    lines_mupy[i_mupy] = b'######## FAIL\n'
+                    break
+                del lines_mupy[i_mupy:i_mupy + skip]
+                lines_mupy.insert(i_mupy, b'########\n')
+                i_mupy += 1
+            else:
+                # a regex
+                if lines_exp[i][1].match(lines_mupy[i_mupy]):
+                    lines_mupy[i_mupy] = lines_exp[i][0]
+                else:
+                    #print("don't match: %r %s" % (lines_exp[i][1], lines_mupy[i_mupy])) # DEBUG
+                    pass
+                i_mupy += 1
+            if i_mupy >= len(lines_mupy):
+                break
+        output_mupy = b''.join(lines_mupy)
+
+    return output_mupy
+
+
+def run_feature_check(pyb, args, base_path, test_file):
+    return run_micropython(pyb, args, base_path + "/feature_check/" + test_file, is_special=True)
+
+class ThreadSafeCounter:
+    def __init__(self, start=0):
+        self._value = start
+        self._lock = threading.Lock()
+
+    def add(self, to_add):
+        with self._lock: self._value += to_add
+
+    def append(self, arg):
+        self.add([arg])
+
+    @property
+    def value(self):
+        return self._value
+
+def run_tests(pyb, tests, args, base_path=".", num_threads=1):
+    test_count = ThreadSafeCounter()
+    testcase_count = ThreadSafeCounter()
+    passed_count = ThreadSafeCounter()
+    failed_tests = ThreadSafeCounter([])
+    skipped_tests = ThreadSafeCounter([])
+
+    skip_tests = set()
+    skip_native = False
+    skip_int_big = False
+    skip_set_type = False
+    skip_async = False
+    skip_const = False
+    skip_revops = False
+    skip_endian = False
+    has_complex = True
+    has_coverage = False
+
+    upy_float_precision = 32
+
+    # Some tests shouldn't be run under Travis CI
+    if os.getenv('TRAVIS') == 'true':
+        skip_tests.add('basics/memoryerror.py')
+        skip_tests.add('thread/thread_gc1.py') # has reliability issues
+        skip_tests.add('thread/thread_lock4.py') # has reliability issues
+        skip_tests.add('thread/stress_heap.py') # has reliability issues
+        skip_tests.add('thread/stress_recurse.py') # has reliability issues
+
+    if upy_float_precision == 0:
+        skip_tests.add('extmod/ujson_dumps_float.py')
+        skip_tests.add('extmod/ujson_loads_float.py')
+        skip_tests.add('misc/rge_sm.py')
+    if upy_float_precision < 32:
+        skip_tests.add('float/float2int_intbig.py') # requires fp32, there's float2int_fp30_intbig.py instead
+        skip_tests.add('float/string_format.py') # requires fp32, there's string_format_fp30.py instead
+        skip_tests.add('float/bytes_construct.py') # requires fp32
+        skip_tests.add('float/bytearray_construct.py') # requires fp32
+    if upy_float_precision < 64:
+        skip_tests.add('float/float_divmod.py') # tested by float/float_divmod_relaxed.py instead
+        skip_tests.add('float/float2int_doubleprec_intbig.py')
+        skip_tests.add('float/float_parse_doubleprec.py')
+
+    if not has_complex:
+        skip_tests.add('float/complex1.py')
+        skip_tests.add('float/complex1_intbig.py')
+        skip_tests.add('float/int_big_float.py')
+        skip_tests.add('float/true_value.py')
+        skip_tests.add('float/types.py')
+
+    if not has_coverage:
+        skip_tests.add('cmdline/cmd_parsetree.py')
+
+    # Some tests shouldn't be run on a PC
+    if args.target == 'unix':
+        # unix build does not have the GIL so can't run thread mutation tests
+        for t in tests:
+            if t.startswith('thread/mutate_'):
+                skip_tests.add(t)
+
+    # Some tests shouldn't be run on pyboard
+    if args.target != 'unix':
+        skip_tests.add('basics/exception_chain.py') # warning is not printed
+        skip_tests.add('micropython/meminfo.py') # output is very different to PC output
+        skip_tests.add('extmod/machine_mem.py') # raw memory access not supported
+
+        if args.target == 'wipy':
+            skip_tests.add('misc/print_exception.py')       # requires error reporting full
+            skip_tests.update({'extmod/uctypes_%s.py' % t for t in 'bytearray le native_le ptr_le ptr_native_le sizeof sizeof_native array_assign_le array_assign_native_le'.split()}) # requires uctypes
+            skip_tests.add('extmod/zlibd_decompress.py')    # requires zlib
+            skip_tests.add('extmod/uheapq1.py')             # uheapq not supported by WiPy
+            skip_tests.add('extmod/urandom_basic.py')       # requires urandom
+            skip_tests.add('extmod/urandom_extra.py')       # requires urandom
+        elif args.target == 'esp8266':
+            skip_tests.add('misc/rge_sm.py')                # too large
+        elif args.target == 'minimal':
+            skip_tests.add('basics/class_inplace_op.py')    # all special methods not supported
+            skip_tests.add('basics/subclass_native_init.py')# native subclassing corner cases not support
+            skip_tests.add('misc/rge_sm.py')                # too large
+            skip_tests.add('micropython/opt_level.py')      # don't assume line numbers are stored
+
+    # Some tests are known to fail on 64-bit machines
+    if pyb is None and platform.architecture()[0] == '64bit':
+        pass
+
+    # Some tests use unsupported features on Windows
+    if os.name == 'nt':
+        skip_tests.add('import/import_file.py') # works but CPython prints forward slashes
+
+    # Some tests are known to fail with native emitter
+    # Remove them from the below when they work
+    if args.emit == 'native':
+        skip_tests.update({'basics/%s.py' % t for t in 'gen_yield_from gen_yield_from_close gen_yield_from_ducktype gen_yield_from_exc gen_yield_from_executing gen_yield_from_iter gen_yield_from_send gen_yield_from_stopped gen_yield_from_throw gen_yield_from_throw2 gen_yield_from_throw3 generator1 generator2 generator_args generator_close generator_closure generator_exc generator_pend_throw generator_return generator_send'.split()}) # require yield
+        skip_tests.update({'basics/%s.py' % t for t in 'bytes_gen class_store_class globals_del string_join gen_stack_overflow'.split()}) # require yield
+        skip_tests.update({'basics/async_%s.py' % t for t in 'def await await2 for for2 with with2 coroutine'.split()}) # require yield
+        skip_tests.update({'basics/%s.py' % t for t in 'try_reraise try_reraise2'.split()}) # require raise_varargs
+        skip_tests.update({'basics/%s.py' % t for t in 'with_break with_continue with_return'.split()}) # require complete with support
+        skip_tests.add('basics/array_construct2.py') # requires generators
+        skip_tests.add('basics/bool1.py') # seems to randomly fail
+        skip_tests.add('basics/builtin_hash_gen.py') # requires yield
+        skip_tests.add('basics/class_bind_self.py') # requires yield
+        skip_tests.add('basics/del_deref.py') # requires checking for unbound local
+        skip_tests.add('basics/del_local.py') # requires checking for unbound local
+        skip_tests.add('basics/exception_chain.py') # raise from is not supported
+        skip_tests.add('basics/for_range.py') # requires yield_value
+        skip_tests.add('basics/try_finally_loops.py') # requires proper try finally code
+        skip_tests.add('basics/try_finally_return.py') # requires proper try finally code
+        skip_tests.add('basics/try_finally_return2.py') # requires proper try finally code
+        skip_tests.add('basics/unboundlocal.py') # requires checking for unbound local
+        skip_tests.add('import/gen_context.py') # requires yield_value
+        skip_tests.add('misc/features.py') # requires raise_varargs
+        skip_tests.add('misc/rge_sm.py') # requires yield
+        skip_tests.add('misc/print_exception.py') # because native doesn't have proper traceback info
+        skip_tests.add('misc/sys_exc_info.py') # sys.exc_info() is not supported for native
+        skip_tests.add('micropython/emg_exc.py') # because native doesn't have proper traceback info
+        skip_tests.add('micropython/heapalloc_traceback.py') # because native doesn't have proper traceback info
+        skip_tests.add('micropython/heapalloc_iter.py') # requires generators
+        skip_tests.add('micropython/schedule.py') # native code doesn't check pending events
+        skip_tests.add('stress/gc_trace.py') # requires yield
+        skip_tests.add('stress/recursive_gen.py') # requires yield
+        skip_tests.add('extmod/vfs_userfs.py') # because native doesn't properly handle globals across different modules
+        skip_tests.add('../extmod/ulab/tests/argminmax.py') # requires yield
+
+    def run_one_test(test_file):
+        test_file = test_file.replace('\\', '/')
+
+        if args.filters:
+            # Default verdict is the opposit of the first action
+            verdict = "include" if args.filters[0][0] == "exclude" else "exclude"
+            for action, pat in args.filters:
+                if pat.search(test_file):
+                    verdict = action
+            if verdict == "exclude":
+                return
+
+        test_basename = os.path.basename(test_file)
+        test_name = os.path.splitext(test_basename)[0]
+        is_native = test_name.startswith("native_") or test_name.startswith("viper_")
+        is_endian = test_name.endswith("_endian")
+        is_int_big = test_name.startswith("int_big") or test_name.endswith("_intbig")
+        is_set_type = test_name.startswith("set_") or test_name.startswith("frozenset")
+        is_async = test_name.startswith("async_")
+        is_const = test_name.startswith("const")
+
+        skip_it = test_file in skip_tests
+        skip_it |= skip_native and is_native
+        skip_it |= skip_endian and is_endian
+        skip_it |= skip_int_big and is_int_big
+        skip_it |= skip_set_type and is_set_type
+        skip_it |= skip_async and is_async
+        skip_it |= skip_const and is_const
+        skip_it |= skip_revops and test_name.startswith("class_reverse_op")
+
+        if args.list_tests:
+            if not skip_it:
+                print(test_file)
+            return
+
+        if skip_it:
+            print("skip ", test_file)
+            skipped_tests.append(test_name)
+            return
+
+        # get expected output
+        test_file_expected = test_file + '.exp'
+        if os.path.isfile(test_file_expected):
+            # expected output given by a file, so read that in
+            with open(test_file_expected, 'rb') as f:
+                output_expected = f.read()
+        else:
+            if not args.write_exp:
+                output_expected = b"NOEXP\n"
+            else:
+                # run CPython to work out expected output
+                e = {"PYTHONPATH": os.getcwd(),
+                     "PATH": os.environ["PATH"],
+                     "LANG": "en_US.UTF-8"}
+                p = subprocess.Popen([MICROPYTHON, test_file], env=e, stdout=subprocess.PIPE)
+                output_expected = b''
+                while p.poll() is None:
+                    output_expected += p.stdout.read()
+                output_expected += p.stdout.read()
+                with open(test_file_expected, 'wb') as f:
+                    f.write(output_expected)
+
+        # canonical form for all host platforms is to use \n for end-of-line
+        output_expected = output_expected.replace(b'\r\n', b'\n')
+
+        if args.write_exp:
+            return
+
+        # run MicroPython
+        output_mupy = run_micropython(pyb, args, test_file)
+
+        if output_mupy == b'SKIP\n':
+            print("skip ", test_file)
+            skipped_tests.append(test_name)
+            return
+
+        if output_expected == b'NOEXP\n':
+            print("noexp", test_file)
+            failed_tests.append(test_name)
+            return
+
+        testcase_count.add(len(output_expected.splitlines()))
+
+        filename_expected = test_basename + ".exp"
+        filename_mupy = test_basename + ".out"
+
+        if output_expected == output_mupy:
+            print("pass ", test_file)
+            passed_count.add(1)
+            rm_f(filename_expected)
+            rm_f(filename_mupy)
+        else:
+            with open(filename_expected, "wb") as f:
+                f.write(output_expected)
+            with open(filename_mupy, "wb") as f:
+                f.write(output_mupy)
+            print("### Expected")
+            print(output_expected)
+            print("### Actual")
+            print(output_mupy)
+            print("FAIL ", test_file)
+            failed_tests.append(test_name)
+
+        test_count.add(1)
+
+    if args.list_tests:
+        return True
+
+    if num_threads > 1:
+        pool = ThreadPool(num_threads)
+        pool.map(run_one_test, tests)
+    else:
+        for test in tests:
+            run_one_test(test)
+
+    print("{} tests performed ({} individual testcases)".format(test_count.value, testcase_count.value))
+    print("{} tests passed".format(passed_count.value))
+
+    if len(skipped_tests.value) > 0:
+        print("{} tests skipped: {}".format(len(skipped_tests.value), ' '.join(sorted(skipped_tests.value))))
+    if len(failed_tests.value) > 0:
+        print("{} tests failed: {}".format(len(failed_tests.value), ' '.join(sorted(failed_tests.value))))
+        return False
+
+    # all tests succeeded
+    return True
+
+
+class append_filter(argparse.Action):
+
+    def __init__(self, option_strings, dest, **kwargs):
+        super().__init__(option_strings, dest, default=[], **kwargs)
+
+    def __call__(self, parser, args, value, option):
+        if not hasattr(args, self.dest):
+            args.filters = []
+        if option.startswith(("-e", "--e")):
+            option = "exclude"
+        else:
+            option = "include"
+        args.filters.append((option, re.compile(value)))
+
+
+def main():
+    cmd_parser = argparse.ArgumentParser(
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+        description='Run and manage tests for MicroPython.',
+        epilog='''\
+Options -i and -e can be multiple and processed in the order given. Regex
+"search" (vs "match") operation is used. An action (include/exclude) of
+the last matching regex is used:
+  run-tests -i async - exclude all, then include tests containg "async" anywhere
+  run-tests -e '/big.+int' - include all, then exclude by regex
+  run-tests -e async -i async_foo - include all, exclude async, yet still include async_foo
+''')
+    cmd_parser.add_argument('--target', default='unix', help='the target platform')
+    cmd_parser.add_argument('--device', default='/dev/ttyACM0', help='the serial device or the IP address of the pyboard')
+    cmd_parser.add_argument('-b', '--baudrate', default=115200, help='the baud rate of the serial device')
+    cmd_parser.add_argument('-u', '--user', default='micro', help='the telnet login username')
+    cmd_parser.add_argument('-p', '--password', default='python', help='the telnet login password')
+    cmd_parser.add_argument('-d', '--test-dirs', nargs='*', help='input test directories (if no files given)')
+    cmd_parser.add_argument('-e', '--exclude', action=append_filter, metavar='REGEX', dest='filters', help='exclude test by regex on path/name.py')
+    cmd_parser.add_argument('-i', '--include', action=append_filter, metavar='REGEX', dest='filters', help='include test by regex on path/name.py')
+    cmd_parser.add_argument('--write-exp', action='store_true', help='save .exp files to run tests w/o CPython')
+    cmd_parser.add_argument('--list-tests', action='store_true', help='list tests instead of running them')
+    cmd_parser.add_argument('--emit', default='bytecode', help='MicroPython emitter to use (bytecode or native)')
+    cmd_parser.add_argument('--heapsize', help='heapsize to use (use default if not specified)')
+    cmd_parser.add_argument('--via-mpy', action='store_true', help='compile .py files to .mpy first')
+    cmd_parser.add_argument('--keep-path', action='store_true', help='do not clear MICROPYPATH when running tests')
+    cmd_parser.add_argument('-j', '--jobs', default=1, metavar='N', type=int, help='Number of tests to run simultaneously')
+    cmd_parser.add_argument('--auto-jobs', action='store_const', dest='jobs', const=multiprocessing.cpu_count(), help='Set the -j values to the CPU (thread) count')
+    cmd_parser.add_argument('files', nargs='*', help='input test files')
+    args = cmd_parser.parse_args()
+
+    EXTERNAL_TARGETS = ('pyboard', 'wipy', 'esp8266', 'esp32', 'minimal')
+    if args.target == 'unix' or args.list_tests:
+        pyb = None
+    elif args.target in EXTERNAL_TARGETS:
+        import pyboard
+        pyb = pyboard.Pyboard(args.device, args.baudrate, args.user, args.password)
+        pyb.enter_raw_repl()
+    else:
+        raise ValueError('target must be either %s or unix' % ", ".join(EXTERNAL_TARGETS))
+
+    if len(args.files) == 0:
+        if args.test_dirs is None:
+            if args.target == 'pyboard':
+                # run pyboard tests
+                test_dirs = ('basics', 'micropython', 'float', 'misc', 'stress', 'extmod', 'pyb', 'pybnative', 'inlineasm')
+            elif args.target in ('esp8266', 'esp32', 'minimal'):
+                test_dirs = ('basics', 'micropython', 'float', 'misc', 'extmod')
+            elif args.target == 'wipy':
+                # run WiPy tests
+                test_dirs = ('basics', 'micropython', 'misc', 'extmod', 'wipy')
+            else:
+                # run PC tests
+                test_dirs = (
+                    'basics', 'micropython', 'float', 'import', 'io', 'misc',
+                    'stress', 'unicode', 'extmod', '../extmod/ulab/tests', 'unix', 'cmdline',
+                )
+        else:
+            # run tests from these directories
+            test_dirs = args.test_dirs
+        tests = sorted(test_file for test_files in (glob('{}/*.py'.format(dir)) for dir in test_dirs) for test_file in test_files)
+    else:
+        # tests explicitly given
+        tests = args.files
+
+    if not args.keep_path:
+        # clear search path to make sure tests use only builtin modules
+        os.environ['MICROPYPATH'] = ''
+
+    # Even if we run completely different tests in a different directory,
+    # we need to access feature_check's from the same directory as the
+    # run-tests script itself.
+    base_path = os.path.dirname(sys.argv[0]) or "."
+    try:
+        res = run_tests(pyb, tests, args, base_path, args.jobs)
+    finally:
+        if pyb:
+            pyb.close()
+
+    if not res:
+        sys.exit(1)
+
+if __name__ == "__main__":
+    main()