Change long/long true division to return as many good bits as it can;

e.g., (1L << 40000)/(1L << 40001) returns 0.5, not Inf or NaN or whatever.

1 files changed, 38 insertions, 0 deletions

diff --git a/Lib/test/test_long_future.py b/Lib/test/test_long_future.py
new file mode 100644
index 0000000..4348bbe
--- /dev/null
+++ b/Lib/test/test_long_future.py
@@ -0,0 +1,38 @@
+from __future__ import division
+# When true division is the default, get rid of this and add it to
+# test_long.py instead.  In the meantime, it's too obscure to try to
+# trick just part of test_long into using future division.
+
+from test_support import TestFailed, verify, verbose
+
+def test_true_division():
+    if verbose:
+        print "long true division"
+    huge = 1L << 40000
+    mhuge = -huge
+    verify(huge / huge == 1.0)
+    verify(mhuge / mhuge == 1.0)
+    verify(huge / mhuge == -1.0)
+    verify(mhuge / huge == -1.0)
+    verify(1 / huge == 0.0)
+    verify(1L / huge == 0.0)
+    verify(1 / mhuge == 0.0)
+    verify(1L / mhuge ==- 0.0)
+    verify((666 * huge + (huge >> 1)) / huge == 666.5)
+    verify((666 * mhuge + (mhuge >> 1)) / mhuge == 666.5)
+    verify((666 * huge + (huge >> 1)) / mhuge == -666.5)
+    verify((666 * mhuge + (mhuge >> 1)) / huge == -666.5)
+    verify(huge / (huge << 1) == 0.5)
+
+    namespace = {'huge': huge, 'mhuge': mhuge}
+    for overflow in ["float(huge)", "float(mhuge)",
+                     "huge / 1", "huge / 2L", "huge / -1", "huge / -2L",
+                     "mhuge / 100", "mhuge / 100L"]:
+        try:
+            eval(overflow, namespace)
+        except OverflowError:
+            pass
+        else:
+            raise TestFailed("expected OverflowError from %r" % overflow)
+
+test_true_division()