TST: Division overflow tests

numpy/core/tests/test_umath.py

@@ -686,6 +686,49 @@ def test_float_remainder_corner_cases(self):
                 assert_(np.isnan(fmod), 'dt: %s, fmod: %s' % (dt, rem))
 
 
+class TestDivisionOverflows:
+    @pytest.mark.parametrize("dividend_dtype",
+            np.sctypes['int'])
+    @pytest.mark.parametrize("divisor_dtype",
+            np.sctypes['int'])
+    @pytest.mark.parametrize("operation",
+            [np.remainder, np.fmod, np.floor_divide])
+    def test_scalars(self, dividend_dtype, divisor_dtype, operation):
+        with np.errstate(divide='raise'):
+            # If dividend is a larger type than the divisor (`else` case),
+            # then, result will be a larger type than dividend and will not
+            # result in an overflow.
+            if np.dtype(dividend_dtype).itemsize >= np.dtype(
+                    divisor_dtype).itemsize:
+                with pytest.raises(FloatingPointError):
+                    operation(
+                        dividend_dtype(np.iinfo(dividend_dtype).min),
+                        divisor_dtype(-1)
+                    )
+            else:
+                operation(
+                    dividend_dtype(np.iinfo(dividend_dtype).min),
+                    divisor_dtype(-1)
+                )
+
+    @pytest.mark.parametrize("dividend_dtype",
+            np.sctypes['int'])
+    @pytest.mark.parametrize("divisor_dtype",
+            np.sctypes['int'])
+    @pytest.mark.parametrize("operation",
+            [np.remainder, np.fmod, np.floor_divide])
+    def test_arrays(self, dividend_dtype, divisor_dtype, operation):
+        # Cover all edge cases in SIMD
+        arrays = [np.array(
+                    [dividend_dtype(
+                        np.iinfo(dividend_dtype).min)]*i
+                    ) for i in range(1, 129)]
+        with np.errstate(divide='raise'):
+            for a in arrays:
+                with pytest.raises(FloatingPointError):
+                    operation(a, divisor_dtype(-1))
+
+
 class TestCbrt:
     def test_cbrt_scalar(self):
         assert_almost_equal((np.cbrt(np.float32(-2.5)**3)), -2.5)