[pypy-commit] pypy math-improvements: improve test coverage by adding an explicit test for a rare case in division

[cfbolz]

Author: Carl Friedrich Bolz-Tereick <cfbolz at gmx.de>
Branch: math-improvements
Changeset: r95472:bab1896b4351
Date: 2018-12-13 13:09 +0100
http://bitbucket.org/pypy/pypy/changeset/bab1896b4351/

Log:	improve test coverage by adding an explicit test for a rare case in
	division

diff --git a/rpython/rlib/test/test_rbigint.py b/rpython/rlib/test/test_rbigint.py
--- a/rpython/rlib/test/test_rbigint.py
+++ b/rpython/rlib/test/test_rbigint.py
@@ -900,6 +900,18 @@
                 assert rem.tolong() == _rem
         py.test.raises(ZeroDivisionError, rbigint.fromlong(x).divmod, rbigint.fromlong(0))
 
+        # an explicit example for a very rare case in _x_divrem:
+        # "add w back if q was too large (this branch taken rarely)"
+        x = 2401064762424988628303678384283622960038813848808995811101817752058392725584695633
+        y = 510439143470502793407446782273075179624699774495710665331026
+        f1 = rbigint.fromlong(x)
+        f2 = rbigint.fromlong(y)
+        div, rem = f1.divmod(f2)
+        _div, _rem = divmod(x, y)
+        assert div.tolong() == _div
+        assert rem.tolong() == _rem
+
+
     def test_int_divmod(self):
         for x in long_vals:
             for y in int_vals + [-sys.maxint-1]: