Raise TypeError instead of ValueError.

Author: serhiy-storchaka

Doc/library/random.rst

@@ -135,6 +135,10 @@ Functions for integers
       values.  Formerly it used a style like ``int(random()*n)`` which could produce
       slightly uneven distributions.
 
+   .. versionchanged:: 3.10
+      Formerly :exc:`ValueError` could be raised for non-integer arguments
+      instead of :exc:`TypeError`.
+
    .. deprecated:: 3.10
       Accepting non-integer arguments is deprecated.
 

Lib/random.py

@@ -303,7 +303,7 @@ def randrange(self, start, stop=None, step=1):
         except TypeError:
             istart = int(start)
             if istart != start:
-                raise ValueError("non-integer arg 1 for randrange()")
+                raise TypeError("non-integer arg 1 for randrange()")
             _warn('non-integer arg 1 for randrange()',
                   DeprecationWarning, 2)
         if stop is None:
@@ -317,7 +317,7 @@ def randrange(self, start, stop=None, step=1):
         except TypeError:
             istop = int(stop)
             if istop != stop:
-                raise ValueError("non-integer stop for randrange()")
+                raise TypeError("non-integer stop for randrange()")
             _warn('non-integer stop for randrange()',
                   DeprecationWarning, 2)
         width = istop - istart
@@ -326,7 +326,7 @@ def randrange(self, start, stop=None, step=1):
         except TypeError:
             istep = int(step)
             if istep != step:
-                raise ValueError("non-integer step for randrange()")
+                raise TypeError("non-integer step for randrange()")
             _warn('non-integer step for randrange()',
                   DeprecationWarning, 2)
         # Fast path.

Lib/test/test_random.py

@@ -504,28 +504,40 @@ def test_randrange_nonunit_step(self):
         rint = self.gen.randrange(0, 2, 2)
         self.assertEqual(rint, 0)
 
+    def test_randrange_non_integers(self):
+        randrange = self.gen.randrange
+        with self.assertWarns(DeprecationWarning):
+            self.assertIn(randrange(3.0), range(3))
+        with self.assertWarns(DeprecationWarning):
+            self.assertIn(randrange(0, 3.0), range(0, 3))
+        with self.assertWarns(DeprecationWarning):
+            self.assertIn(randrange(0, 42, 1.0), range(0, 42, 1))
+        with self.assertWarns(DeprecationWarning):
+            self.assertIn(randrange(0, 42, 3.0), range(0, 42, 3))
+
     def test_randrange_errors(self):
-        raises = partial(self.assertRaises, ValueError, self.gen.randrange)
+        randrange = self.gen.randrange
+        raises = partial(self.assertRaises, ValueError, randrange)
         # Empty range
         raises(3, 3)
         raises(-721)
         raises(0, 100, -12)
         self.assertWarns(DeprecationWarning, raises, 3, 3, 1.0)
         # Non-integer start/stop
-        raises(3.14159)
-        self.assertWarns(DeprecationWarning, self.gen.randrange, 3.0)
-        self.assertWarns(DeprecationWarning, self.gen.randrange, Fraction(3, 1))
-        raises('3')
-        raises(0, 2.71828)
-        self.assertWarns(DeprecationWarning, self.gen.randrange, 0, 2.0)
-        self.assertWarns(DeprecationWarning, self.gen.randrange, 0, Fraction(2, 1))
-        raises(0, '2')
+        self.assertRaises(TypeError, randrange, 3.14159)
+        self.assertWarns(DeprecationWarning, randrange, 3.0)
+        self.assertWarns(DeprecationWarning, randrange, Fraction(3, 1))
+        self.assertRaises(TypeError, randrange, '3')
+        self.assertRaises(TypeError, randrange, 0, 2.71828)
+        self.assertWarns(DeprecationWarning, randrange, 0, 2.0)
+        self.assertWarns(DeprecationWarning, randrange, 0, Fraction(2, 1))
+        self.assertRaises(TypeError, randrange, 0, '2')
         # Zero and non-integer step
         raises(0, 42, 0)
-        raises(0, 42, 3.14159)
-        self.assertWarns(DeprecationWarning, self.gen.randrange, 0, 42, 3.0)
-        self.assertWarns(DeprecationWarning, self.gen.randrange, 0, 42, Fraction(3, 1))
-        raises(0, 42, '3')
+        self.assertRaises(TypeError, randrange, 0, 42, 3.14159)
+        self.assertWarns(DeprecationWarning, randrange, 0, 42, 3.0)
+        self.assertWarns(DeprecationWarning, randrange, 0, 42, Fraction(3, 1))
+        self.assertRaises(TypeError, randrange, 0, 42, '3')
 
     def test_randbelow_logic(self, _log=log, int=int):
         # check bitcount transition points:  2**i and 2**(i+1)-1

Misc/NEWS.d/next/Library/2020-03-22-21-33-31.bpo-37319.BrIAir.rst

@@ -1 +1,3 @@
 Deprecated support of non-integer arguments in :func:`random.randrange`.
+:exc:`TypeError` is now always raised for wrong type of arguments
+(formerly :exc:`ValueError` could be raised for some non-integer arguments).