Merged revisions 80753 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/trunk

........
  r80753 | mark.dickinson | 2010-05-04 15:25:50 +0100 (Tue, 04 May 2010) | 10 lines

  Issue #8567: Fix incorrect precedence of signals in Decimal module.

  When a Decimal operation raises multiple signals and more than one of
  those signals is trapped, the specification determines the order in
  which the signals should be handled.  In many cases this order wasn't
  being followed, leading to the wrong Python exception being raised.
  This commit fixes those cases, and adds extra tests.  The tests are
  only enabled when EXTENDEDERRORTESTS is True, since they involve
  rerunning each Decimal testcase several times.
........

1 files changed, 25 insertions, 0 deletions

diff --git a/Lib/test/test_decimal.py b/Lib/test/test_decimal.py
index d6e170d1e4..21590880b0 100644
--- a/Lib/test/test_decimal.py
+++ b/Lib/test/test_decimal.py
@@ -41,6 +41,12 @@ except ImportError:
 # Useful Test Constant
 Signals = tuple(getcontext().flags.keys())
 
+# Signals ordered with respect to precedence: when an operation
+# produces multiple signals, signals occurring later in the list
+# should be handled before those occurring earlier in the list.
+OrderedSignals = (Clamped, Rounded, Inexact, Subnormal,
+                  Underflow, Overflow, DivisionByZero, InvalidOperation)
+
 # Tests are built around these assumed context defaults.
 # test_main() restores the original context.
 def init():
@@ -351,6 +357,25 @@ class DecimalTest(unittest.TestCase):
                 else:
                     self.fail("Did not raise %s in %s" % (error, s))
                 self.context.traps[error] = 0
+
+            # as above, but add traps cumulatively, to check precedence
+            ordered_errors = [e for e in OrderedSignals if e in theirexceptions]
+            for error in ordered_errors:
+                self.context.traps[error] = 1
+                try:
+                    funct(*vals)
+                except error:
+                    pass
+                except Signals as e:
+                    self.fail("Raised %s in %s; expected %s" %
+                              (type(e), s, error))
+                else:
+                    self.fail("Did not raise %s in %s" % (error, s))
+            # reset traps
+            for error in ordered_errors:
+                self.context.traps[error] = 0
+
+
         if DEBUG:
             print("--", self.context)
         try: