tests/run-tests: Introduce generic "minimal" target.

Used e.g. by Zephyr port.

tests/run-tests

@@ -290,6 +290,9 @@ def run_tests(pyb, tests, args):
             skip_tests.add('float/bytes_construct.py')      # requires fp32
             skip_tests.add('float/bytearray_construct.py')  # requires fp32
             skip_tests.add('misc/rge_sm.py')                # too large
+        elif args.target == 'minimal':
+            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':
@@ -429,7 +432,7 @@ def main():
     cmd_parser.add_argument('files', nargs='*', help='input test files')
     args = cmd_parser.parse_args()
 
-    EXTERNAL_TARGETS = ('pyboard', 'wipy', 'esp8266')
+    EXTERNAL_TARGETS = ('pyboard', 'wipy', 'esp8266', 'minimal')
     if args.target in EXTERNAL_TARGETS:
         import pyboard
         pyb = pyboard.Pyboard(args.device, args.baudrate, args.user, args.password)
@@ -444,7 +447,7 @@ def main():
             if args.target == 'pyboard':
                 # run pyboard tests
                 test_dirs = ('basics', 'micropython', 'float', 'misc', 'stress', 'extmod', 'pyb', 'pybnative', 'inlineasm')
-            elif args.target == 'esp8266':
+            elif args.target in ('esp8266', 'minimal'):
                 test_dirs = ('basics', 'micropython', 'float', 'misc', 'extmod')
             elif args.target == 'wipy':
                 # run WiPy tests