Issue #21407: _decimal now supports function signatures.

Lib/test/test_decimal.py

@@ -39,6 +39,7 @@ from test.support import (check_warnings, import_fresh_module, TestFailed,
 import random
 import time
 import warnings
+import inspect
 try:
     import threading
 except ImportError:
@@ -5390,6 +5391,142 @@ class CWhitebox(unittest.TestCase):
             y = Decimal(10**(9*25)).__sizeof__()
             self.assertEqual(y, x+4)
 
+unittest.skipUnless(C, "test requires C version")
+class SignatureTest(unittest.TestCase):
+    """Function signatures"""
+
+    def test_inspect_module(self):
+        for attr in dir(P):
+            if attr.startswith('_'):
+                continue
+            p_func = getattr(P, attr)
+            c_func = getattr(C, attr)
+            if (attr == 'Decimal' or attr == 'Context' or
+                inspect.isfunction(p_func)):
+                p_sig = inspect.signature(p_func)
+                c_sig = inspect.signature(c_func)
+
+                # parameter names:
+                c_names = list(c_sig.parameters.keys())
+                p_names = [x for x in p_sig.parameters.keys() if not
+                           x.startswith('_')]
+
+                self.assertEqual(c_names, p_names,
+                                 msg="parameter name mismatch in %s" % p_func)
+
+                c_kind = [x.kind for x in c_sig.parameters.values()]
+                p_kind = [x[1].kind for x in p_sig.parameters.items() if not
+                          x[0].startswith('_')]
+
+                # parameters:
+                if attr != 'setcontext':
+                    self.assertEqual(c_kind, p_kind,
+                                     msg="parameter kind mismatch in %s" % p_func)
+
+    def test_inspect_types(self):
+
+        POS = inspect._ParameterKind.POSITIONAL_ONLY
+        POS_KWD = inspect._ParameterKind.POSITIONAL_OR_KEYWORD
+
+        # Type heuristic (type annotations would help!):
+        pdict = {C: {'other': C.Decimal(1),
+                     'third': C.Decimal(1),
+                     'x': C.Decimal(1),
+                     'y': C.Decimal(1),
+                     'z': C.Decimal(1),
+                     'a': C.Decimal(1),
+                     'b': C.Decimal(1),
+                     'c': C.Decimal(1),
+                     'exp': C.Decimal(1),
+                     'modulo': C.Decimal(1),
+                     'num': "1",
+                     'f': 1.0,
+                     'rounding': C.ROUND_HALF_UP,
+                     'context': C.getcontext()},
+                 P: {'other': P.Decimal(1),
+                     'third': P.Decimal(1),
+                     'a': P.Decimal(1),
+                     'b': P.Decimal(1),
+                     'c': P.Decimal(1),
+                     'exp': P.Decimal(1),
+                     'modulo': P.Decimal(1),
+                     'num': "1",
+                     'f': 1.0,
+                     'rounding': P.ROUND_HALF_UP,
+                     'context': P.getcontext()}}
+
+        def mkargs(module, sig):
+            args = []
+            kwargs = {}
+            for name, param in sig.parameters.items():
+                if name == 'self': continue
+                if param.kind == POS:
+                    args.append(pdict[module][name])
+                elif param.kind == POS_KWD:
+                    kwargs[name] = pdict[module][name]
+                else:
+                    raise TestFailed("unexpected parameter kind")
+            return args, kwargs
+
+        def tr(s):
+            """The C Context docstrings use 'x' in order to prevent confusion
+               with the article 'a' in the descriptions."""
+            if s == 'x': return 'a'
+            if s == 'y': return 'b'
+            if s == 'z': return 'c'
+            return s
+
+        def doit(ty):
+            p_type = getattr(P, ty)
+            c_type = getattr(C, ty)
+            for attr in dir(p_type):
+                if attr.startswith('_'):
+                    continue
+                p_func = getattr(p_type, attr)
+                c_func = getattr(c_type, attr)
+                if inspect.isfunction(p_func):
+                    p_sig = inspect.signature(p_func)
+                    c_sig = inspect.signature(c_func)
+
+                    # parameter names:
+                    p_names = list(p_sig.parameters.keys())
+                    c_names = [tr(x) for x in c_sig.parameters.keys()]
+
+                    self.assertEqual(c_names, p_names,
+                                     msg="parameter name mismatch in %s" % p_func)
+
+                    p_kind = [x.kind for x in p_sig.parameters.values()]
+                    c_kind = [x.kind for x in c_sig.parameters.values()]
+
+                    # 'self' parameter:
+                    self.assertIs(p_kind[0], POS_KWD)
+                    self.assertIs(c_kind[0], POS)
+
+                    # remaining parameters:
+                    if ty == 'Decimal':
+                        self.assertEqual(c_kind[1:], p_kind[1:],
+                                         msg="parameter kind mismatch in %s" % p_func)
+                    else: # Context methods are positional only in the C version.
+                        self.assertEqual(len(c_kind), len(p_kind),
+                                         msg="parameter kind mismatch in %s" % p_func)
+
+                    # Run the function:
+                    args, kwds = mkargs(C, c_sig)
+                    try:
+                        getattr(c_type(9), attr)(*args, **kwds)
+                    except Exception as err:
+                        raise TestFailed("invalid signature for %s: %s %s" % (c_func, args, kwds))
+
+                    args, kwds = mkargs(P, p_sig)
+                    try:
+                        getattr(p_type(9), attr)(*args, **kwds)
+                    except Exception as err:
+                        raise TestFailed("invalid signature for %s: %s %s" % (p_func, args, kwds))
+
+        doit('Decimal')
+        doit('Context')
+
+
 all_tests = [
   CExplicitConstructionTest, PyExplicitConstructionTest,
   CImplicitConstructionTest, PyImplicitConstructionTest,
@@ -5415,6 +5552,7 @@ if not C:
     all_tests = all_tests[1::2]
 else:
     all_tests.insert(0, CheckAttributes)
+    all_tests.insert(1, SignatureTest)
 
 
 def test_main(arith=False, verbose=None, todo_tests=None, debug=None):

Misc/NEWS

@@ -310,6 +310,8 @@ Library
 Extension Modules
 -----------------
 
+- Issue #21407: _decimal: The module now supports function signatures.
+
 - Issue #21276: posixmodule: Don't define USE_XATTRS on KFreeBSD and the Hurd.
 
 IDLE