tests/cpydiff: Add initial set of tests for uPy-CPython differences.

These tests are intended to fail, as they provide a programatic record of
differences between uPy and CPython.  They also contain a special comment
at the start of the file which has meta-data describing the difference,
including known causes and known workarounds.

tests/cpydiff/syntax_spaces.py

+"""
+categories: Syntax,Spaces
+description: uPy requires spaces between literal numbers and keywords, CPy doesn't
+cause: Unknown
+workaround: Unknown
+"""
+try:
+    print(eval('1and 0'))
+except SyntaxError:
+    print('Should have worked')
+try:
+    print(eval('1or 0'))
+except SyntaxError:
+    print('Should have worked')
+try:
+    print(eval('1if 1else 0'))
+except SyntaxError:
+    print('Should have worked')

tests/cpydiff/syntax_unicode_nameesc.py

+"""
+categories: Syntax,Unicode
+description: Unicode name escapes are not implemented
+cause: Unknown
+workaround: Unknown
+"""
+print("\N{LATIN SMALL LETTER A}")

tests/cpydiff/types_bytearray_sliceassign.py

+"""
+categories: Types,bytearray
+description: Array slice assignment with unsupported RHS
+cause: Unknown
+workaround: Unknown
+"""
+b = bytearray(4)
+b[0:1] = [1, 2]
+print(b)

tests/cpydiff/types_bytes_keywords.py

+"""
+categories: Types,bytes
+description: bytes(...) with keywords not implemented
+cause: Unknown
+workaround: Input the encoding format directly. eg. ``print(bytes('abc', 'utf-8'))``
+"""
+print(bytes('abc', encoding='utf8'))

tests/cpydiff/types_bytes_subscrstep.py

+"""
+categories: Types,bytes
+description: Bytes subscr with step != 1 not implemented
+cause: Unknown
+workaround: Unknown
+"""
+print(b'123'[0:3:2])

tests/cpydiff/types_exception_chaining.py

+"""
+categories: Types,Exception
+description: Exception chaining not implemented
+cause: Unknown
+workaround: Unknown
+"""
+try:
+    raise TypeError
+except TypeError:
+    raise ValueError

tests/cpydiff/types_exception_instancevar.py

+"""
+categories: Types,Exception
+description: Assign instance variable to exception
+cause: Unknown
+workaround: Unknown
+"""
+e = Exception()
+e.x = 0
+print(e.x)

tests/cpydiff/types_exception_loops.py

+"""
+categories: Types,Exception
+description: While loop guards will obscure exception line number reporting due to being optimised onto the end of the code block
+cause: Unknown
+workaround: Unknown
+"""
+l = ["-foo", "-bar"]
+
+i = 0
+while l[i][0] == "-":
+    print("iter")
+    i += 1

tests/cpydiff/types_exception_subclassinit.py

+"""
+categories: Types,Exception
+description: Exception.__init__ raises TypeError if overridden and called by subclass
+cause: Unknown
+workaround: Unknown
+"""
+class A(Exception):
+    def __init__(self):
+        Exception.__init__(self)
+
+a = A()

tests/cpydiff/types_float_rounding.py

+"""
+categories: Types,float
+description: uPy and CPython outputs formats differ
+cause: Unknown
+workaround: Unknown
+"""
+print('%.1g' % -9.9)
+print('%.1e' % 9.99)
+print('%.1e' % 0.999)

tests/cpydiff/types_int_subclassconv.py

+"""
+categories: Types,int
+description: No int conversion for int-derived types available
+cause: Unknown
+workaround: Unknown
+"""
+class A(int):
+    __add__ = lambda self, other: A(int(self) + other)
+
+a = A(42)
+print(a+a)

tests/cpydiff/types_int_tobytesfloat.py

+"""
+categories: Types,int
+description: Incorrect error message when passing float into to_bytes
+cause: Unknown
+workaround: Unknown
+"""
+try:
+    int('1').to_bytes(1.0)
+except TypeError as e:
+    print(e)

tests/cpydiff/types_list_delete_subscrstep.py

+"""
+categories: Types,list
+description: List delete with step != 1 not implemented
+cause: Unknown
+workaround: Unknown
+"""
+l = [1, 2, 3, 4]
+del l[0:4:2]
+print(l)

tests/cpydiff/types_list_store_subscrstep.py

+"""
+categories: Types,list
+description: List store with step != 1 not implemented
+cause: Unknown
+workaround: Unknown
+"""
+l = [1, 2, 3, 4]
+l[0:4:2] = [5, 6]
+print(l)

tests/cpydiff/types_str_decodeerror.py

+"""
+categories: Types,str
+description: UnicodeDecodeError not raised when expected
+cause: Unknown
+workaround: Unknown
+"""
+try:
+    print(repr(str(b"\xa1\x80", 'utf8')))
+    print('Should not get here')
+except UnicodeDecodeError:
+    print('UnicodeDecodeError')

tests/cpydiff/types_str_endswith.py

+"""
+categories: Types,str
+description: Start/end indices such as str.endswith(s, start) not implemented
+cause: Unknown
+workaround: Unknown
+"""
+print('abc'.endswith('c', 1))

tests/cpydiff/types_str_formatsubscr.py

+"""
+categories: Types,str
+description: Attributes/subscr not implemented
+cause: Unknown
+workaround: Unknown
+"""
+print('{a[0]}'.format(a=[1, 2]))

tests/cpydiff/types_str_keywords.py

+"""
+categories: Types,str
+description: str(...) with keywords not implemented
+cause: Unknown
+workaround: Input the encoding format directly. eg ``print(bytes('abc', 'utf-8'))``
+"""
+print(str(b'abc', encoding='utf8'))

tests/cpydiff/types_str_rsplitnone.py

+"""
+categories: Types,str
+description: None as first argument for rsplit such as str.rsplit(None, n) not implemented
+cause: Unknown
+workaround: Unknown
+"""
+print('a a a'.rsplit(None, 1))

tests/cpydiff/types_str_subclassequality.py

+"""
+categories: Types,str
+description: Instance of a subclass of str cannot be compared for equality with an instance of a str
+cause: Unknown
+workaround: Unknown
+"""
+class S(str):
+    pass
+
+s = S('hello')
+print(s == 'hello')