MAINT: Produce a different error message when length is NaN

Also, improve tests.

2 files changed, 43 insertions, 22 deletions

diff --git a/numpy/core/src/multiarray/ctors.c b/numpy/core/src/multiarray/ctors.c
index 319e17a46..f4236f36d 100644
--- a/numpy/core/src/multiarray/ctors.c
+++ b/numpy/core/src/multiarray/ctors.c
@@ -2935,18 +2935,25 @@ PyArray_Empty(int nd, npy_intp *dims, PyArray_Descr *type, int is_f_order)
  * Return 0 on success, -1 on failure. In case of failure, set a PyExc_Overflow
  * exception
  */
-static int _safe_ceil_to_intp(double value, npy_intp* ret)
+static npy_intp
+_arange_safe_ceil_to_intp(double value)
 {
     double ivalue;
 
     ivalue = npy_ceil(value);
     /* condition inverted to handle NaN */
+    if (npy_isnan(ivalue)) {
+        PyErr_SetString(PyExc_ValueError,
+            "arange: cannot compute length");
+        return -1;
+    }
     if (!(NPY_MIN_INTP <= ivalue && ivalue <= NPY_MAX_INTP)) {
+        PyErr_SetString(PyExc_OverflowError,
+                "arange: overflow while computing length");
         return -1;
     }
 
-    *ret = (npy_intp)ivalue;
-    return 0;
+    return (npy_intp)ivalue;
 }
 
 
@@ -2963,9 +2970,8 @@ PyArray_Arange(double start, double stop, double step, int type_num)
     int ret;
     NPY_BEGIN_THREADS_DEF;
 
-    if (_safe_ceil_to_intp((stop - start)/step, &length)) {
-        PyErr_SetString(PyExc_OverflowError,
-                "arange: overflow while computing length");
+    length = _arange_safe_ceil_to_intp((stop - start)/step);
+    if (error_converting(length)) {
         return NULL;
     }
 
@@ -3055,10 +3061,9 @@ _calc_length(PyObject *start, PyObject *stop, PyObject *step, PyObject **next, i
             Py_DECREF(val);
             return -1;
         }
-        if (_safe_ceil_to_intp(value, &len)) {
+        len = _arange_safe_ceil_to_intp(value);
+        if (error_converting(len)) {
             Py_DECREF(val);
-            PyErr_SetString(PyExc_OverflowError,
-                    "arange: overflow while computing length");
             return -1;
         }
         value = PyComplex_ImagAsDouble(val);
@@ -3066,9 +3071,8 @@ _calc_length(PyObject *start, PyObject *stop, PyObject *step, PyObject **next, i
         if (error_converting(value)) {
             return -1;
         }
-        if (_safe_ceil_to_intp(value, &tmp)) {
-            PyErr_SetString(PyExc_OverflowError,
-                    "arange: overflow while computing length");
+        tmp = _arange_safe_ceil_to_intp(value);
+        if (error_converting(tmp)) {
             return -1;
         }
         len = PyArray_MIN(len, tmp);
@@ -3079,9 +3083,8 @@ _calc_length(PyObject *start, PyObject *stop, PyObject *step, PyObject **next, i
         if (error_converting(value)) {
             return -1;
         }
-        if (_safe_ceil_to_intp(value, &len)) {
-            PyErr_SetString(PyExc_OverflowError,
-                    "arange: overflow while computing length");
+        len = _arange_safe_ceil_to_intp(value);
+        if (error_converting(len)) {
             return -1;
         }
     }
diff --git a/numpy/core/tests/test_multiarray.py b/numpy/core/tests/test_multiarray.py
index f55bd0e2b..fdd34b6c0 100644
--- a/numpy/core/tests/test_multiarray.py
+++ b/numpy/core/tests/test_multiarray.py
@@ -1643,7 +1643,7 @@ class TestMethods(object):
         arr = np.array([0, datetime.now(), 1], dtype=object)
         for kind in ['q', 'm', 'h']:
             assert_raises(TypeError, arr.sort, kind=kind)
-        #gh-3879 
+        #gh-3879
         class Raiser(object):
             def raises_anything(*args, **kwargs):
                 raise TypeError("SOMETHING ERRORED")
@@ -7196,8 +7196,30 @@ class TestWritebackIfCopy(TestCase):
         assert_(not arr_wb.ctypes.data == 0)
         arr_wb[:] = 100
         assert_equal(arr, -100)
-        
-        
+
+
+class TestArange(object):
+    def test_infinite(self):
+        assert_raises_regex(
+            ValueError, "size exceeded",
+            np.arange, 0, np.inf
+        )
+
+    def test_nan_step(self):
+        assert_raises_regex(
+            ValueError, "cannot compute length",
+            np.arange, 0, 1, np.nan
+        )
+
+    def test_zero_step(self):
+        assert_raises(ZeroDivisionError, np.arange, 0, 10, 0)
+        assert_raises(ZeroDivisionError, np.arange, 0.0, 10.0, 0.0)
+
+        # empty range
+        assert_raises(ZeroDivisionError, np.arange, 0, 0, 0)
+        assert_raises(ZeroDivisionError, np.arange, 0.0, 0.0, 0.0)
+
+
 def test_orderconverter_with_nonASCII_unicode_ordering():
     # gh-7475
     a = np.arange(5)
@@ -7270,10 +7292,6 @@ def test_npymath_real():
                 expected = npfun(z)
                 assert_allclose(got, expected)
 
-# Test when (stop - start) / step is NaN, ValueError is raised instead
-# of returning a zero-length array.
-def test_arange_nan():
-    assert_raises(ValueError, np.arange, 0, 1, np.nan)
 
 if __name__ == "__main__":
     run_module_suite()