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Issue 8257: Decimal constructor to accept float.

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This commit is contained in:
Raymond Hettinger 2010-04-02 18:39:24 +00:00
parent dc36d7cf85
commit ed171abd93
3 changed files with 45 additions and 11 deletions
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26
Lib/test/test_decimal.py
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@ -54,6 +54,11 @@ def init():
)
setcontext(DefaultTestContext)
# decorator for skipping tests on non-IEEE 754 platforms
requires_IEEE_754 = unittest.skipUnless(
float.__getformat__("double").startswith("IEEE"),
"test requires IEEE 754 doubles")
TESTDATADIR = 'decimaltestdata'
if __name__ == '__main__':
file = sys.argv[0]
@ -509,6 +514,27 @@ class DecimalExplicitConstructionTest(unittest.TestCase):
self.assertEqual(str(e), '0')
self.assertNotEqual(id(d), id(e))
@requires_IEEE_754
def test_explicit_from_float(self):
r = Decimal(0.1)
self.assertEqual(type(r), Decimal)
self.assertEqual(str(r),
'0.1000000000000000055511151231257827021181583404541015625')
self.assertTrue(Decimal(float('nan')).is_qnan())
self.assertTrue(Decimal(float('inf')).is_infinite())
self.assertTrue(Decimal(float('-inf')).is_infinite())
self.assertEqual(str(Decimal(float('nan'))),
str(Decimal('NaN')))
self.assertEqual(str(Decimal(float('inf'))),
str(Decimal('Infinity')))
self.assertEqual(str(Decimal(float('-inf'))),
str(Decimal('-Infinity')))
self.assertEqual(str(Decimal(float('-0.0'))),
str(Decimal('-0')))
for i in range(200):
x = random.expovariate(0.01) * (random.random() * 2.0 - 1.0)
self.assertEqual(x, float(Decimal(x))) # roundtrip
def test_explicit_context_create_decimal(self):
nc = copy.copy(getcontext())