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Diffstat (limited to 'tests/run/test_named_expressions.py')
| -rw-r--r-- | tests/run/test_named_expressions.py | 559 |
1 files changed, 559 insertions, 0 deletions
diff --git a/tests/run/test_named_expressions.py b/tests/run/test_named_expressions.py new file mode 100644 index 000000000..304749c92 --- /dev/null +++ b/tests/run/test_named_expressions.py @@ -0,0 +1,559 @@ +# mode: run +# tag: pure3.8, no-cpp + +# copied from cpython with minimal modifications (mainly exec->cython_inline, and a few exception strings) +# This is not currently run in C++ because all the cython_inline compilations fail for reasons that are unclear +# cython: language_level=3 + +import unittest +import cython +from Cython.Compiler.Main import CompileError +from Cython.Build.Inline import cython_inline +import re +import sys + +if cython.compiled: + try: + from StringIO import StringIO + except ImportError: + from io import StringIO + + class StdErrHider: + def __enter__(self): + self.old_stderr = sys.stderr + self.new_stderr = StringIO() + sys.stderr = self.new_stderr + + return self + + def __exit__(self, exc_type, exc_value, traceback): + sys.stderr = self.old_stderr + + @property + def stderr_contents(self): + return self.new_stderr.getvalue() + + def exec(code, globals_=None, locals_=None): + if locals_ and globals_ and (locals_ is not globals_): + # a hacky attempt to treat as a class definition + code = "class Cls:\n" + "\n".join( + " " + line for line in code.split("\n")) + code += "\nreturn globals(), locals()" # so we can inspect it for changes, overriding the default cython_inline behaviour + try: + with StdErrHider() as stderr_handler: + try: + g, l = cython_inline(code, globals=globals_, locals=locals_) + finally: + err_messages = stderr_handler.stderr_contents + if globals_ is not None: + # because Cython inline bundles everything into a function some values that + # we'd expect to be in globals end up in locals. This isn't quite right but is + # as close as it's possible to get to retrieving the values + globals_.update(l) + globals_.update(g) + except CompileError as exc: + raised_message = str(exc) + if raised_message.endswith(".pyx"): + # unhelpfully Cython sometimes raises a compile error and sometimes just raises the filename + raised_message = [] + for line in err_messages.split("\n"): + # search for the two line number groups (we can't just split by ':' because Windows + # filenames contain ':') + match = re.match(r"(.+?):\d+:\d+:(.*)", line) + # a usable error message with be filename:line:char: message + if match and match.group(1).endswith(".pyx"): + raised_message.append(match.group(2)) + # output all the errors - we aren't worried about reproducing the exact order CPython + # emits errors in + raised_message = "; ".join(raised_message) + raise SyntaxError(raised_message) from None + +if sys.version_info[0] < 3: + # some monkey patching + unittest.TestCase.assertRaisesRegex = unittest.TestCase.assertRaisesRegexp + + class FakeSubTest(object): + def __init__(self, *args, **kwds): + pass + def __enter__(self): + pass + def __exit__(self, *args): + pass + unittest.TestCase.subTest = FakeSubTest + +class NamedExpressionInvalidTest(unittest.TestCase): + + def test_named_expression_invalid_01(self): + code = """x := 0""" + + with self.assertRaisesRegex(SyntaxError, "invalid syntax"): + exec(code, {}, {}) + + def test_named_expression_invalid_02(self): + code = """x = y := 0""" + + with self.assertRaisesRegex(SyntaxError, "invalid syntax"): + exec(code, {}, {}) + + def test_named_expression_invalid_03(self): + code = """y := f(x)""" + + with self.assertRaisesRegex(SyntaxError, "invalid syntax"): + exec(code, {}, {}) + + def test_named_expression_invalid_04(self): + code = """y0 = y1 := f(x)""" + + with self.assertRaisesRegex(SyntaxError, "invalid syntax"): + exec(code, {}, {}) + + def test_named_expression_invalid_06(self): + code = """((a, b) := (1, 2))""" + + # TODO Cython correctly generates an error but the message could be better + with self.assertRaisesRegex(SyntaxError, ""): + exec(code, {}, {}) + + def test_named_expression_invalid_07(self): + code = """def spam(a = b := 42): pass""" + + with self.assertRaisesRegex(SyntaxError, "invalid syntax"): + exec(code, {}, {}) + + def test_named_expression_invalid_08(self): + code = """def spam(a: b := 42 = 5): pass""" + + with self.assertRaisesRegex(SyntaxError, "invalid syntax"): + exec(code, {}, {}) + + def test_named_expression_invalid_09(self): + code = """spam(a=b := 'c')""" + + with self.assertRaisesRegex(SyntaxError, "invalid syntax"): + exec(code, {}, {}) + + def test_named_expression_invalid_10(self): + code = """spam(x = y := f(x))""" + + with self.assertRaisesRegex(SyntaxError, "invalid syntax"): + exec(code, {}, {}) + + def test_named_expression_invalid_11(self): + code = """spam(a=1, b := 2)""" + + with self.assertRaisesRegex(SyntaxError, + "follow.* keyword arg"): + exec(code, {}, {}) + + def test_named_expression_invalid_12(self): + code = """spam(a=1, (b := 2))""" + + with self.assertRaisesRegex(SyntaxError, + "follow.* keyword arg"): + exec(code, {}, {}) + + def test_named_expression_invalid_13(self): + code = """spam(a=1, (b := 2))""" + + with self.assertRaisesRegex(SyntaxError, + "follow.* keyword arg"): + exec(code, {}, {}) + + def test_named_expression_invalid_14(self): + code = """(x := lambda: y := 1)""" + + with self.assertRaisesRegex(SyntaxError, "invalid syntax"): + exec(code, {}, {}) + + def test_named_expression_invalid_15(self): + code = """(lambda: x := 1)""" + + # TODO at the moment the error message is valid, but not the same as Python + with self.assertRaisesRegex(SyntaxError, + ""): + exec(code, {}, {}) + + def test_named_expression_invalid_16(self): + code = "[i + 1 for i in i := [1,2]]" + + # TODO at the moment the error message is valid, but not the same as Python + with self.assertRaisesRegex(SyntaxError, ""): + exec(code, {}, {}) + + def test_named_expression_invalid_17(self): + code = "[i := 0, j := 1 for i, j in [(1, 2), (3, 4)]]" + + # TODO at the moment the error message is valid, but not the same as Python + with self.assertRaisesRegex(SyntaxError, ""): + exec(code, {}, {}) + + def test_named_expression_invalid_in_class_body(self): + code = """class Foo(): + [(42, 1 + ((( j := i )))) for i in range(5)] + """ + + with self.assertRaisesRegex(SyntaxError, + "assignment expression within a comprehension cannot be used in a class body"): + exec(code, {}, {}) + + def test_named_expression_invalid_rebinding_comprehension_iteration_variable(self): + cases = [ + ("Local reuse", 'i', "[i := 0 for i in range(5)]"), + ("Nested reuse", 'j', "[[(j := 0) for i in range(5)] for j in range(5)]"), + ("Reuse inner loop target", 'j', "[(j := 0) for i in range(5) for j in range(5)]"), + ("Unpacking reuse", 'i', "[i := 0 for i, j in [(0, 1)]]"), + ("Reuse in loop condition", 'i', "[i+1 for i in range(5) if (i := 0)]"), + ("Unreachable reuse", 'i', "[False or (i:=0) for i in range(5)]"), + ("Unreachable nested reuse", 'i', + "[(i, j) for i in range(5) for j in range(5) if True or (i:=10)]"), + ] + for case, target, code in cases: + msg = f"assignment expression cannot rebind comprehension iteration variable '{target}'" + with self.subTest(case=case): + with self.assertRaisesRegex(SyntaxError, msg): + exec(code, {}, {}) + + def test_named_expression_invalid_rebinding_comprehension_inner_loop(self): + cases = [ + ("Inner reuse", 'j', "[i for i in range(5) if (j := 0) for j in range(5)]"), + ("Inner unpacking reuse", 'j', "[i for i in range(5) if (j := 0) for j, k in [(0, 1)]]"), + ] + for case, target, code in cases: + msg = f"comprehension inner loop cannot rebind assignment expression target '{target}'" + with self.subTest(case=case): + with self.assertRaisesRegex(SyntaxError, msg): + exec(code, {}) # Module scope + with self.assertRaisesRegex(SyntaxError, msg): + exec(code, {}, {}) # Class scope + with self.assertRaisesRegex(SyntaxError, msg): + exec(f"lambda: {code}", {}) # Function scope + + def test_named_expression_invalid_comprehension_iterable_expression(self): + cases = [ + ("Top level", "[i for i in (i := range(5))]"), + ("Inside tuple", "[i for i in (2, 3, i := range(5))]"), + ("Inside list", "[i for i in [2, 3, i := range(5)]]"), + ("Different name", "[i for i in (j := range(5))]"), + ("Lambda expression", "[i for i in (lambda:(j := range(5)))()]"), + ("Inner loop", "[i for i in range(5) for j in (i := range(5))]"), + ("Nested comprehension", "[i for i in [j for j in (k := range(5))]]"), + ("Nested comprehension condition", "[i for i in [j for j in range(5) if (j := True)]]"), + ("Nested comprehension body", "[i for i in [(j := True) for j in range(5)]]"), + ] + msg = "assignment expression cannot be used in a comprehension iterable expression" + for case, code in cases: + with self.subTest(case=case): + with self.assertRaisesRegex(SyntaxError, msg): + exec(code, {}) # Module scope - FIXME this test puts it in __invoke in cython_inline + with self.assertRaisesRegex(SyntaxError, msg): + exec(code, {}, {}) # Class scope + with self.assertRaisesRegex(SyntaxError, msg): + exec(f"lambda: {code}", {}) # Function scope + + +class NamedExpressionAssignmentTest(unittest.TestCase): + + def test_named_expression_assignment_01(self): + (a := 10) + + self.assertEqual(a, 10) + + def test_named_expression_assignment_02(self): + a = 20 + (a := a) + + self.assertEqual(a, 20) + + def test_named_expression_assignment_03(self): + (total := 1 + 2) + + self.assertEqual(total, 3) + + def test_named_expression_assignment_04(self): + (info := (1, 2, 3)) + + self.assertEqual(info, (1, 2, 3)) + + def test_named_expression_assignment_05(self): + (x := 1, 2) + + self.assertEqual(x, 1) + + def test_named_expression_assignment_06(self): + (z := (y := (x := 0))) + + self.assertEqual(x, 0) + self.assertEqual(y, 0) + self.assertEqual(z, 0) + + def test_named_expression_assignment_07(self): + (loc := (1, 2)) + + self.assertEqual(loc, (1, 2)) + + def test_named_expression_assignment_08(self): + if spam := "eggs": + self.assertEqual(spam, "eggs") + else: self.fail("variable was not assigned using named expression") + + def test_named_expression_assignment_09(self): + if True and (spam := True): + self.assertTrue(spam) + else: self.fail("variable was not assigned using named expression") + + def test_named_expression_assignment_10(self): + if (match := 10) == 10: + pass + else: self.fail("variable was not assigned using named expression") + + def test_named_expression_assignment_11(self): + def spam(a): + return a + input_data = [1, 2, 3] + res = [(x, y, x/y) for x in input_data if (y := spam(x)) > 0] + + self.assertEqual(res, [(1, 1, 1.0), (2, 2, 1.0), (3, 3, 1.0)]) + + def test_named_expression_assignment_12(self): + def spam(a): + return a + res = [[y := spam(x), x/y] for x in range(1, 5)] + + self.assertEqual(res, [[1, 1.0], [2, 1.0], [3, 1.0], [4, 1.0]]) + + def test_named_expression_assignment_13(self): + length = len(lines := [1, 2]) + + self.assertEqual(length, 2) + self.assertEqual(lines, [1,2]) + + def test_named_expression_assignment_14(self): + """ + Where all variables are positive integers, and a is at least as large + as the n'th root of x, this algorithm returns the floor of the n'th + root of x (and roughly doubling the number of accurate bits per + iteration): + """ + a = 9 + n = 2 + x = 3 + + while a > (d := x // a**(n-1)): + a = ((n-1)*a + d) // n + + self.assertEqual(a, 1) + + def test_named_expression_assignment_15(self): + while a := False: + pass # This will not run + + self.assertEqual(a, False) + + def test_named_expression_assignment_16(self): + a, b = 1, 2 + fib = {(c := a): (a := b) + (b := a + c) - b for __ in range(6)} + self.assertEqual(fib, {1: 2, 2: 3, 3: 5, 5: 8, 8: 13, 13: 21}) + + +class NamedExpressionScopeTest(unittest.TestCase): + + def test_named_expression_scope_01(self): + code = """def spam(): + (a := 5) +print(a)""" + + # FIXME for some reason the error message raised is a nonsense filename instead of "undeclared name not builtin" + # "name .* not"): + with self.assertRaisesRegex(SyntaxError if cython.compiled else NameError, ""): + exec(code, {}, {}) + + def test_named_expression_scope_02(self): + total = 0 + partial_sums = [total := total + v for v in range(5)] + + self.assertEqual(partial_sums, [0, 1, 3, 6, 10]) + self.assertEqual(total, 10) + + def test_named_expression_scope_03(self): + containsOne = any((lastNum := num) == 1 for num in [1, 2, 3]) + + self.assertTrue(containsOne) + self.assertEqual(lastNum, 1) + + def test_named_expression_scope_04(self): + def spam(a): + return a + res = [[y := spam(x), x/y] for x in range(1, 5)] + + self.assertEqual(y, 4) + + def test_named_expression_scope_05(self): + def spam(a): + return a + input_data = [1, 2, 3] + res = [(x, y, x/y) for x in input_data if (y := spam(x)) > 0] + + self.assertEqual(res, [(1, 1, 1.0), (2, 2, 1.0), (3, 3, 1.0)]) + self.assertEqual(y, 3) + + def test_named_expression_scope_06(self): + res = [[spam := i for i in range(3)] for j in range(2)] + + self.assertEqual(res, [[0, 1, 2], [0, 1, 2]]) + self.assertEqual(spam, 2) + + def test_named_expression_scope_07(self): + len(lines := [1, 2]) + + self.assertEqual(lines, [1, 2]) + + def test_named_expression_scope_08(self): + def spam(a): + return a + + def eggs(b): + return b * 2 + + res = [spam(a := eggs(b := h)) for h in range(2)] + + self.assertEqual(res, [0, 2]) + self.assertEqual(a, 2) + self.assertEqual(b, 1) + + def test_named_expression_scope_09(self): + def spam(a): + return a + + def eggs(b): + return b * 2 + + res = [spam(a := eggs(a := h)) for h in range(2)] + + self.assertEqual(res, [0, 2]) + self.assertEqual(a, 2) + + def test_named_expression_scope_10(self): + res = [b := [a := 1 for i in range(2)] for j in range(2)] + + self.assertEqual(res, [[1, 1], [1, 1]]) + self.assertEqual(a, 1) + self.assertEqual(b, [1, 1]) + + def test_named_expression_scope_11(self): + res = [j := i for i in range(5)] + + self.assertEqual(res, [0, 1, 2, 3, 4]) + self.assertEqual(j, 4) + + def test_named_expression_scope_17(self): + b = 0 + res = [b := i + b for i in range(5)] + + self.assertEqual(res, [0, 1, 3, 6, 10]) + self.assertEqual(b, 10) + + def test_named_expression_scope_18(self): + def spam(a): + return a + + res = spam(b := 2) + + self.assertEqual(res, 2) + self.assertEqual(b, 2) + + def test_named_expression_scope_19(self): + def spam(a): + return a + + res = spam((b := 2)) + + self.assertEqual(res, 2) + self.assertEqual(b, 2) + + def test_named_expression_scope_20(self): + def spam(a): + return a + + res = spam(a=(b := 2)) + + self.assertEqual(res, 2) + self.assertEqual(b, 2) + + def test_named_expression_scope_21(self): + def spam(a, b): + return a + b + + res = spam(c := 2, b=1) + + self.assertEqual(res, 3) + self.assertEqual(c, 2) + + def test_named_expression_scope_22(self): + def spam(a, b): + return a + b + + res = spam((c := 2), b=1) + + self.assertEqual(res, 3) + self.assertEqual(c, 2) + + def test_named_expression_scope_23(self): + def spam(a, b): + return a + b + + res = spam(b=(c := 2), a=1) + + self.assertEqual(res, 3) + self.assertEqual(c, 2) + + def test_named_expression_scope_24(self): + a = 10 + def spam(): + nonlocal a + (a := 20) + spam() + + self.assertEqual(a, 20) + + def test_named_expression_scope_25(self): + ns = {} + code = """a = 10 +def spam(): + global a + (a := 20) +spam()""" + + exec(code, ns, {}) + + self.assertEqual(ns["a"], 20) + + def test_named_expression_variable_reuse_in_comprehensions(self): + # The compiler is expected to raise syntax error for comprehension + # iteration variables, but should be fine with rebinding of other + # names (e.g. globals, nonlocals, other assignment expressions) + + # The cases are all defined to produce the same expected result + # Each comprehension is checked at both function scope and module scope + rebinding = "[x := i for i in range(3) if (x := i) or not x]" + filter_ref = "[x := i for i in range(3) if x or not x]" + body_ref = "[x for i in range(3) if (x := i) or not x]" + nested_ref = "[j for i in range(3) if x or not x for j in range(3) if (x := i)][:-3]" + cases = [ + ("Rebind global", f"x = 1; result = {rebinding}"), + ("Rebind nonlocal", f"result, x = (lambda x=1: ({rebinding}, x))()"), + ("Filter global", f"x = 1; result = {filter_ref}"), + ("Filter nonlocal", f"result, x = (lambda x=1: ({filter_ref}, x))()"), + ("Body global", f"x = 1; result = {body_ref}"), + ("Body nonlocal", f"result, x = (lambda x=1: ({body_ref}, x))()"), + ("Nested global", f"x = 1; result = {nested_ref}"), + ("Nested nonlocal", f"result, x = (lambda x=1: ({nested_ref}, x))()"), + ] + for case, code in cases: + with self.subTest(case=case): + ns = {} + exec(code, ns) + self.assertEqual(ns["x"], 2) + self.assertEqual(ns["result"], [0, 1, 2]) + +if __name__ == "__main__": + unittest.main() |