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 """
 472
 473 import re
 474 import unittest
 475 import warnings
 476
 477 from test import test_support
 478
 479 class SyntaxTestCase(unittest.TestCase):
 480
 481     def _check_error(self, code, errtext,
 482                      filename="<testcase>", mode="exec", subclass=None):
 483         """Check that compiling code raises SyntaxError with errtext.
 484
 485         errtest is a regular expression that must be present in the
 486         test of the exception raised.  If subclass is specified it
 487         is the expected subclass of SyntaxError (e.g. IndentationError).
 488         """
 489         try:
 490             compile(code, filename, mode)
 491         except SyntaxError, err:
 492             if subclass and not isinstance(err, subclass):
 493                 self.fail("SyntaxError is not a %s" % subclass.__name__)
 494             mo = re.search(errtext, str(err))
 495             if mo is None:
 496                 self.fail("%s did not contain '%r'" % (err, errtext,))
 497         else:
 498             self.fail("compile() did not raise SyntaxError")
 499
 500     def test_paren_arg_with_default(self):
 501         self._check_error("def f((x)=23): pass",
 502                           "parenthesized arg with default")
 503
 504     def test_assign_call(self):
 505         self._check_error("f() = 1", "assign")
 506
 507     def test_assign_del(self):
 508         self._check_error("del f()", "delete")
 509
 510     def test_global_err_then_warn(self):
 511         # Bug tickler:  The SyntaxError raised for one global statement
 512         # shouldn't be clobbered by a SyntaxWarning issued for a later one.
 513         source = re.sub('(?m)^ *:', '', """\
 514             :def error(a):
 515             :    global a  # SyntaxError
 516             :def warning():
 517             :    b = 1
 518             :    global b  # SyntaxWarning
 519             :""")
 520         warnings.filterwarnings(action='ignore', category=SyntaxWarning)
 521         self._check_error(source, "global")
 522         warnings.filters.pop(0)
 523
 524     def test_break_outside_loop(self):
 525         self._check_error("break", "outside loop")
 526
 527     def test_delete_deref(self):
 528         source = re.sub('(?m)^ *:', '', """\
 529             :def foo(x):
 530             :  def bar():
 531             :    print x
 532             :  del x
 533             :""")
 534         self._check_error(source, "nested scope")
 535
 536     def test_unexpected_indent(self):
 537         self._check_error("foo()\n bar()\n", "unexpected indent",
 538                           subclass=IndentationError)
 539
 540     def test_no_indent(self):
 541         self._check_error("if 1:\nfoo()", "expected an indented block",
 542                           subclass=IndentationError)
 543
 544     def test_bad_outdent(self):
 545         self._check_error("if 1:\n  foo()\n bar()",
 546                           "unindent does not match .* level",
 547                           subclass=IndentationError)
 548
 549     def test_kwargs_last(self):
 550         self._check_error("int(base=10, '2')", "non-keyword arg")
 551
 552 def test_main():
 553     test_support.run_unittest(SyntaxTestCase)
 554     from test import test_syntax
 555     test_support.run_doctest(test_syntax, verbosity=True)
 556
 557 if __name__ == "__main__":
 558     test_main()