Lib/test/test_syntax.py

   1 """This module tests SyntaxErrors.
   2
   3 Here's an example of the sort of thing that is tested.
   4
   5 >>> def f(x):
   6 ...     global x
   7 Traceback (most recent call last):
   8 SyntaxError: name 'x' is local and global (<doctest test.test_syntax[0]>, line 1)
   9
  10 The tests are all raise SyntaxErrors.  They were created by checking
  11 each C call that raises SyntaxError.  There are several modules that
  12 raise these exceptions-- ast.c, compile.c, future.c, pythonrun.c, and
  13 symtable.c.
  14
  15 The parser itself outlaws a lot of invalid syntax.  None of these
  16 errors are tested here at the moment.  We should add some tests; since
  17 there are infinitely many programs with invalid syntax, we would need
  18 to be judicious in selecting some.
  19
  20 The compiler generates a synthetic module name for code executed by
  21 doctest.  Since all the code comes from the same module, a suffix like
  22 [1] is appended to the module name, As a consequence, changing the
  23 order of tests in this module means renumbering all the errors after
  24 it.  (Maybe we should enable the ellipsis option for these tests.)
  25
  26 In ast.c, syntax errors are raised by calling ast_error().
  27
  28 Errors from set_context():
  29
  30 >>> obj.None = 1
  31 Traceback (most recent call last):
  32   File "<doctest test.test_syntax[1]>", line 1
  33 SyntaxError: cannot assign to None
  34
  35 >>> None = 1
  36 Traceback (most recent call last):
  37   File "<doctest test.test_syntax[2]>", line 1
  38 SyntaxError: cannot assign to None
  39
  40 It's a syntax error to assign to the empty tuple.  Why isn't it an
  41 error to assign to the empty list?  It will always raise some error at
  42 runtime.
  43
  44 >>> () = 1
  45 Traceback (most recent call last):
  46   File "<doctest test.test_syntax[3]>", line 1
  47 SyntaxError: can't assign to ()
  48
  49 >>> f() = 1
  50 Traceback (most recent call last):
  51   File "<doctest test.test_syntax[4]>", line 1
  52 SyntaxError: can't assign to function call
  53
  54 >>> del f()
  55 Traceback (most recent call last):
  56   File "<doctest test.test_syntax[5]>", line 1
  57 SyntaxError: can't delete function call
  58
  59 >>> a + 1 = 2
  60 Traceback (most recent call last):
  61   File "<doctest test.test_syntax[6]>", line 1
  62 SyntaxError: can't assign to operator
  63
  64 >>> (x for x in x) = 1
  65 Traceback (most recent call last):
  66   File "<doctest test.test_syntax[7]>", line 1
  67 SyntaxError: can't assign to generator expression
  68
  69 >>> 1 = 1
  70 Traceback (most recent call last):
  71   File "<doctest test.test_syntax[8]>", line 1
  72 SyntaxError: can't assign to literal
  73
  74 >>> "abc" = 1
  75 Traceback (most recent call last):
  76   File "<doctest test.test_syntax[8]>", line 1
  77 SyntaxError: can't assign to literal
  78
  79 >>> `1` = 1
  80 Traceback (most recent call last):
  81   File "<doctest test.test_syntax[10]>", line 1
  82 SyntaxError: can't assign to repr
  83
  84 If the left-hand side of an assignment is a list or tuple, an illegal
  85 expression inside that contain should still cause a syntax error.
  86 This test just checks a couple of cases rather than enumerating all of
  87 them.
  88
  89 >>> (a, "b", c) = (1, 2, 3)
  90 Traceback (most recent call last):
  91   File "<doctest test.test_syntax[11]>", line 1
  92 SyntaxError: can't assign to literal
  93
  94 >>> [a, b, c + 1] = [1, 2, 3]
  95 Traceback (most recent call last):
  96   File "<doctest test.test_syntax[12]>", line 1
  97 SyntaxError: can't assign to operator
  98
  99 >>> a if 1 else b = 1
 100 Traceback (most recent call last):
 101   File "<doctest test.test_syntax[13]>", line 1
 102 SyntaxError: can't assign to conditional expression
 103
 104 From compiler_complex_args():
 105
 106 >>> def f(None=1):
 107 ...     pass
 108 Traceback (most recent call last):
 109   File "<doctest test.test_syntax[14]>", line 1
 110 SyntaxError: cannot assign to None
 111
 112
 113 From ast_for_arguments():
 114
 115 >>> def f(x, y=1, z):
 116 ...     pass
 117 Traceback (most recent call last):
 118   File "<doctest test.test_syntax[15]>", line 1
 119 SyntaxError: non-default argument follows default argument
 120
 121 >>> def f(x, None):
 122 ...     pass
 123 Traceback (most recent call last):
 124   File "<doctest test.test_syntax[16]>", line 1
 125 SyntaxError: cannot assign to None
 126
 127 >>> def f(*None):
 128 ...     pass
 129 Traceback (most recent call last):
 130   File "<doctest test.test_syntax[17]>", line 1
 131 SyntaxError: cannot assign to None
 132
 133 >>> def f(**None):
 134 ...     pass
 135 Traceback (most recent call last):
 136   File "<doctest test.test_syntax[18]>", line 1
 137 SyntaxError: cannot assign to None
 138
 139
 140 From ast_for_funcdef():
 141
 142 >>> def None(x):
 143 ...     pass
 144 Traceback (most recent call last):
 145   File "<doctest test.test_syntax[19]>", line 1
 146 SyntaxError: cannot assign to None
 147
 148
 149 From ast_for_call():
 150
 151 >>> def f(it, *varargs):
 152 ...     return list(it)
 153 >>> L = range(10)
 154 >>> f(x for x in L)
 155 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
 156 >>> f(x for x in L, 1)
 157 Traceback (most recent call last):
 158   File "<doctest test.test_syntax[23]>", line 1
 159 SyntaxError: Generator expression must be parenthesized if not sole argument
 160 >>> f((x for x in L), 1)
 161 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
 162
 163 >>> f(i0,  i1,  i2,  i3,  i4,  i5,  i6,  i7,  i8,  i9,  i10,  i11,
 164 ...   i12,  i13,  i14,  i15,  i16,  i17,  i18,  i19,  i20,  i21,  i22,
 165 ...   i23,  i24,  i25,  i26,  i27,  i28,  i29,  i30,  i31,  i32,  i33,
 166 ...   i34,  i35,  i36,  i37,  i38,  i39,  i40,  i41,  i42,  i43,  i44,
 167 ...   i45,  i46,  i47,  i48,  i49,  i50,  i51,  i52,  i53,  i54,  i55,
 168 ...   i56,  i57,  i58,  i59,  i60,  i61,  i62,  i63,  i64,  i65,  i66,
 169 ...   i67,  i68,  i69,  i70,  i71,  i72,  i73,  i74,  i75,  i76,  i77,
 170 ...   i78,  i79,  i80,  i81,  i82,  i83,  i84,  i85,  i86,  i87,  i88,
 171 ...   i89,  i90,  i91,  i92,  i93,  i94,  i95,  i96,  i97,  i98,  i99,
 172 ...   i100,  i101,  i102,  i103,  i104,  i105,  i106,  i107,  i108,
 173 ...   i109,  i110,  i111,  i112,  i113,  i114,  i115,  i116,  i117,
 174 ...   i118,  i119,  i120,  i121,  i122,  i123,  i124,  i125,  i126,
 175 ...   i127,  i128,  i129,  i130,  i131,  i132,  i133,  i134,  i135,
 176 ...   i136,  i137,  i138,  i139,  i140,  i141,  i142,  i143,  i144,
 177 ...   i145,  i146,  i147,  i148,  i149,  i150,  i151,  i152,  i153,
 178 ...   i154,  i155,  i156,  i157,  i158,  i159,  i160,  i161,  i162,
 179 ...   i163,  i164,  i165,  i166,  i167,  i168,  i169,  i170,  i171,
 180 ...   i172,  i173,  i174,  i175,  i176,  i177,  i178,  i179,  i180,
 181 ...   i181,  i182,  i183,  i184,  i185,  i186,  i187,  i188,  i189,
 182 ...   i190,  i191,  i192,  i193,  i194,  i195,  i196,  i197,  i198,
 183 ...   i199,  i200,  i201,  i202,  i203,  i204,  i205,  i206,  i207,
 184 ...   i208,  i209,  i210,  i211,  i212,  i213,  i214,  i215,  i216,
 185 ...   i217,  i218,  i219,  i220,  i221,  i222,  i223,  i224,  i225,
 186 ...   i226,  i227,  i228,  i229,  i230,  i231,  i232,  i233,  i234,
 187 ...   i235,  i236,  i237,  i238,  i239,  i240,  i241,  i242,  i243,
 188 ...   i244,  i245,  i246,  i247,  i248,  i249,  i250,  i251,  i252,
 189 ...   i253,  i254,  i255)
 190 Traceback (most recent call last):
 191   File "<doctest test.test_syntax[25]>", line 1
 192 SyntaxError: more than 255 arguments
 193
 194 The actual error cases counts positional arguments, keyword arguments,
 195 and generator expression arguments separately.  This test combines the
 196 three.
 197
 198 >>> f(i0,  i1,  i2,  i3,  i4,  i5,  i6,  i7,  i8,  i9,  i10,  i11,
 199 ...   i12,  i13,  i14,  i15,  i16,  i17,  i18,  i19,  i20,  i21,  i22,
 200 ...   i23,  i24,  i25,  i26,  i27,  i28,  i29,  i30,  i31,  i32,  i33,
 201 ...   i34,  i35,  i36,  i37,  i38,  i39,  i40,  i41,  i42,  i43,  i44,
 202 ...   i45,  i46,  i47,  i48,  i49,  i50,  i51,  i52,  i53,  i54,  i55,
 203 ...   i56,  i57,  i58,  i59,  i60,  i61,  i62,  i63,  i64,  i65,  i66,
 204 ...   i67,  i68,  i69,  i70,  i71,  i72,  i73,  i74,  i75,  i76,  i77,
 205 ...   i78,  i79,  i80,  i81,  i82,  i83,  i84,  i85,  i86,  i87,  i88,
 206 ...   i89,  i90,  i91,  i92,  i93,  i94,  i95,  i96,  i97,  i98,  i99,
 207 ...   i100,  i101,  i102,  i103,  i104,  i105,  i106,  i107,  i108,
 208 ...   i109,  i110,  i111,  i112,  i113,  i114,  i115,  i116,  i117,
 209 ...   i118,  i119,  i120,  i121,  i122,  i123,  i124,  i125,  i126,
 210 ...   i127,  i128,  i129,  i130,  i131,  i132,  i133,  i134,  i135,
 211 ...   i136,  i137,  i138,  i139,  i140,  i141,  i142,  i143,  i144,
 212 ...   i145,  i146,  i147,  i148,  i149,  i150,  i151,  i152,  i153,
 213 ...   i154,  i155,  i156,  i157,  i158,  i159,  i160,  i161,  i162,
 214 ...   i163,  i164,  i165,  i166,  i167,  i168,  i169,  i170,  i171,
 215 ...   i172,  i173,  i174,  i175,  i176,  i177,  i178,  i179,  i180,
 216 ...   i181,  i182,  i183,  i184,  i185,  i186,  i187,  i188,  i189,
 217 ...   i190,  i191,  i192,  i193,  i194,  i195,  i196,  i197,  i198,
 218 ...   i199,  i200,  i201,  i202,  i203,  i204,  i205,  i206,  i207,
 219 ...   i208,  i209,  i210,  i211,  i212,  i213,  i214,  i215,  i216,
 220 ...   i217,  i218,  i219,  i220,  i221,  i222,  i223,  i224,  i225,
 221 ...   i226,  i227,  i228,  i229,  i230,  i231,  i232,  i233,  i234,
 222 ...   i235, i236,  i237,  i238,  i239,  i240,  i241,  i242,  i243,
 223 ...   (x for x in i244),  i245,  i246,  i247,  i248,  i249,  i250,  i251,
 224 ...    i252=1, i253=1,  i254=1,  i255=1)
 225 Traceback (most recent call last):
 226   File "<doctest test.test_syntax[26]>", line 1
 227 SyntaxError: more than 255 arguments
 228
 229 >>> f(lambda x: x[0] = 3)
 230 Traceback (most recent call last):
 231   File "<doctest test.test_syntax[27]>", line 1
 232 SyntaxError: lambda cannot contain assignment
 233
 234 The grammar accepts any test (basically, any expression) in the
 235 keyword slot of a call site.  Test a few different options.
 236
 237 >>> f(x()=2)
 238 Traceback (most recent call last):
 239   File "<doctest test.test_syntax[28]>", line 1
 240 SyntaxError: keyword can't be an expression
 241 >>> f(a or b=1)
 242 Traceback (most recent call last):
 243   File "<doctest test.test_syntax[29]>", line 1
 244 SyntaxError: keyword can't be an expression
 245 >>> f(x.y=1)
 246 Traceback (most recent call last):
 247   File "<doctest test.test_syntax[30]>", line 1
 248 SyntaxError: keyword can't be an expression
 249
 250
 251 More set_context():
 252
 253 >>> (x for x in x) += 1
 254 Traceback (most recent call last):
 255   File "<doctest test.test_syntax[31]>", line 1
 256 SyntaxError: can't assign to generator expression
 257 >>> None += 1
 258 Traceback (most recent call last):
 259   File "<doctest test.test_syntax[32]>", line 1
 260 SyntaxError: cannot assign to None
 261 >>> f() += 1
 262 Traceback (most recent call last):
 263   File "<doctest test.test_syntax[33]>", line 1
 264 SyntaxError: can't assign to function call
 265
 266
 267 Test continue in finally in weird combinations.
 268
 269 continue in for loop under finally shouuld be ok.
 270
 271     >>> def test():
 272     ...     try:
 273     ...         pass
 274     ...     finally:
 275     ...         for abc in range(10):
 276     ...             continue
 277     ...     print abc
 278     >>> test()
 279     9
 280
 281 Start simple, a continue in a finally should not be allowed.
 282
 283     >>> def test():
 284     ...    for abc in range(10):
 285     ...        try:
 286     ...            pass
 287     ...        finally:
 288     ...            continue
 289     Traceback (most recent call last):
 290       ...
 291       File "<doctest test.test_syntax[36]>", line 6
 292     SyntaxError: 'continue' not supported inside 'finally' clause
 293
 294 This is essentially a continue in a finally which should not be allowed.
 295
 296     >>> def test():
 297     ...    for abc in range(10):
 298     ...        try:
 299     ...            pass
 300     ...        finally:
 301     ...            try:
 302     ...                continue
 303     ...            except:
 304     ...                pass
 305     Traceback (most recent call last):
 306       ...
 307       File "<doctest test.test_syntax[37]>", line 6
 308     SyntaxError: 'continue' not supported inside 'finally' clause
 309
 310     >>> def foo():
 311     ...     try:
 312     ...         pass
 313     ...     finally:
 314     ...         continue
 315     Traceback (most recent call last):
 316       ...
 317       File "<doctest test.test_syntax[38]>", line 5
 318     SyntaxError: 'continue' not supported inside 'finally' clause
 319
 320     >>> def foo():
 321     ...     for a in ():
 322     ...       try:
 323     ...           pass
 324     ...       finally:
 325     ...           continue
 326     Traceback (most recent call last):
 327       ...
 328       File "<doctest test.test_syntax[39]>", line 6
 329     SyntaxError: 'continue' not supported inside 'finally' clause
 330
 331     >>> def foo():
 332     ...     for a in ():
 333     ...         try:
 334     ...             pass
 335     ...         finally:
 336     ...             try:
 337     ...                 continue
 338     ...             finally:
 339     ...                 pass
 340     Traceback (most recent call last):
 341       ...
 342       File "<doctest test.test_syntax[40]>", line 7
 343     SyntaxError: 'continue' not supported inside 'finally' clause
 344
 345     >>> def foo():
 346     ...  for a in ():
 347     ...   try: pass
 348     ...   finally:
 349     ...    try:
 350     ...     pass
 351     ...    except:
 352     ...     continue
 353     Traceback (most recent call last):
 354       ...
 355       File "<doctest test.test_syntax[41]>", line 8
 356     SyntaxError: 'continue' not supported inside 'finally' clause
 357
 358 There is one test for a break that is not in a loop.  The compiler
 359 uses a single data structure to keep track of try-finally and loops,
 360 so we need to be sure that a break is actually inside a loop.  If it
 361 isn't, there should be a syntax error.
 362
 363    >>> try:
 364    ...     print 1
 365    ...     break
 366    ...     print 2
 367    ... finally:
 368    ...     print 3
 369    Traceback (most recent call last):
 370      ...
 371      File "<doctest test.test_syntax[42]>", line 3
 372    SyntaxError: 'break' outside loop
 373
 374 This should probably raise a better error than a SystemError (or none at all).
 375 In 2.5 there was a missing exception and an assert was triggered in a debug
 376 build.  The number of blocks must be greater than CO_MAXBLOCKS.  SF #1565514
 377
 378    >>> while 1:
 379    ...  while 2:
 380    ...   while 3:
 381    ...    while 4:
 382    ...     while 5:
 383    ...      while 6:
 384    ...       while 8:
 385    ...        while 9:
 386    ...         while 10:
 387    ...          while 11:
 388    ...           while 12:
 389    ...            while 13:
 390    ...             while 14:
 391    ...              while 15:
 392    ...               while 16:
 393    ...                while 17:
 394    ...                 while 18:
 395    ...                  while 19:
 396    ...                   while 20:
 397    ...                    while 21:
 398    ...                     while 22:
 399    ...                      break
 400    Traceback (most recent call last):
 401      ...
 402    SystemError: too many statically nested blocks
 403
 404 This tests assignment-context; there was a bug in Python 2.5 where compiling
 405 a complex 'if' (one with 'elif') would fail to notice an invalid suite,
 406 leading to spurious errors.
 407
 408    >>> if 1:
 409    ...   x() = 1
 410    ... elif 1:
 411    ...   pass
 412    Traceback (most recent call last):
 413      ...
 414      File "<doctest test.test_syntax[44]>", line 2
 415    SyntaxError: can't assign to function call
 416
 417    >>> if 1:
 418    ...   pass
 419    ... elif 1:
 420    ...   x() = 1
 421    Traceback (most recent call last):
 422      ...
 423      File "<doctest test.test_syntax[45]>", line 4
 424    SyntaxError: can't assign to function call
 425
 426    >>> if 1:
 427    ...   x() = 1
 428    ... elif 1:
 429    ...   pass
 430    ... else:
 431    ...   pass
 432    Traceback (most recent call last):
 433      ...
 434      File "<doctest test.test_syntax[46]>", line 2
 435    SyntaxError: can't assign to function call
 436
 437    >>> if 1:
 438    ...   pass
 439    ... elif 1:
 440    ...   x() = 1
 441    ... else:
 442    ...   pass
 443    Traceback (most recent call last):
 444      ...
 445      File "<doctest test.test_syntax[47]>", line 4
 446    SyntaxError: can't assign to function call
 447
 448    >>> if 1:
 449    ...   pass
 450    ... elif 1:
 451    ...   pass
 452    ... else:
 453    ...   x() = 1
 454    Traceback (most recent call last):
 455      ...
 456      File "<doctest test.test_syntax[48]>", line 6
 457    SyntaxError: can't assign to function call
 458
 459 >>> f(a=23, a=234)
 460 Traceback (most recent call last):
 461    ...
 462   File "<doctest test.test_syntax[49]>", line 1
 463 SyntaxError: keyword argument repeated
 464
 465 >>> del ()
 466 Traceback (most recent call last):
 467    ...
 468   File "<doctest test.test_syntax[50]>", line 1
 469 SyntaxError: can't delete ()
 470
 471 >>> {1, 2, 3} = 42
 472 Traceback (most recent call last):
 473    ...
 474    File "<doctest test.test_syntax[50]>", line 1
 475 SyntaxError: can't assign to literal
 476
 477 """
 478
 479 import re
 480 import unittest
 481 import warnings
 482
 483 from test import test_support
 484
 485 class SyntaxTestCase(unittest.TestCase):
 486
 487     def _check_error(self, code, errtext,
 488                      filename="<testcase>", mode="exec", subclass=None):
 489         """Check that compiling code raises SyntaxError with errtext.
 490
 491         errtest is a regular expression that must be present in the
 492         test of the exception raised.  If subclass is specified it
 493         is the expected subclass of SyntaxError (e.g. IndentationError).
 494         """
 495         try:
 496             compile(code, filename, mode)
 497         except SyntaxError, err:
 498             if subclass and not isinstance(err, subclass):
 499                 self.fail("SyntaxError is not a %s" % subclass.__name__)
 500             mo = re.search(errtext, str(err))
 501             if mo is None:
 502                 self.fail("%s did not contain '%r'" % (err, errtext,))
 503         else:
 504             self.fail("compile() did not raise SyntaxError")
 505
 506     def test_paren_arg_with_default(self):
 507         self._check_error("def f((x)=23): pass",
 508                           "parenthesized arg with default")
 509
 510     def test_assign_call(self):
 511         self._check_error("f() = 1", "assign")
 512
 513     def test_assign_del(self):
 514         self._check_error("del f()", "delete")
 515
 516     def test_global_err_then_warn(self):
 517         # Bug tickler:  The SyntaxError raised for one global statement
 518         # shouldn't be clobbered by a SyntaxWarning issued for a later one.
 519         source = re.sub('(?m)^ *:', '', """\
 520             :def error(a):
 521             :    global a  # SyntaxError
 522             :def warning():
 523             :    b = 1
 524             :    global b  # SyntaxWarning
 525             :""")
 526         warnings.filterwarnings(action='ignore', category=SyntaxWarning)
 527         self._check_error(source, "global")
 528         warnings.filters.pop(0)
 529
 530     def test_break_outside_loop(self):
 531         self._check_error("break", "outside loop")
 532
 533     def test_delete_deref(self):
 534         source = re.sub('(?m)^ *:', '', """\
 535             :def foo(x):
 536             :  def bar():
 537             :    print x
 538             :  del x
 539             :""")
 540         self._check_error(source, "nested scope")
 541
 542     def test_unexpected_indent(self):
 543         self._check_error("foo()\n bar()\n", "unexpected indent",
 544                           subclass=IndentationError)
 545
 546     def test_no_indent(self):
 547         self._check_error("if 1:\nfoo()", "expected an indented block",
 548                           subclass=IndentationError)
 549
 550     def test_bad_outdent(self):
 551         self._check_error("if 1:\n  foo()\n bar()",
 552                           "unindent does not match .* level",
 553                           subclass=IndentationError)
 554
 555     def test_kwargs_last(self):
 556         self._check_error("int(base=10, '2')", "non-keyword arg")
 557
 558 def test_main():
 559     test_support.run_unittest(SyntaxTestCase)
 560     from test import test_syntax
 561     with test_support.check_py3k_warnings(("backquote not supported",
 562                                              SyntaxWarning)):
 563         test_support.run_doctest(test_syntax, verbosity=True)
 564
 565 if __name__ == "__main__":
 566     test_main()