Merge pull request numpy#12604 from danielhrisca/fromfile-bugfix

BUG: Check dtype and formats arguments for None in numpy.core.records.fromfile

numpy/core/records.py

@@ -721,7 +721,7 @@ def fromstring(datastring, dtype=None, shape=None, offset=0, formats=None,
     a string"""
 
     if dtype is None and formats is None:
-        raise ValueError("Must have dtype= or formats=")
+        raise TypeError("fromstring() needs a 'dtype' or 'formats' argument")
 
     if dtype is not None:
         descr = sb.dtype(dtype)
@@ -768,6 +768,9 @@ def fromfile(fd, dtype=None, shape=None, offset=0, formats=None,
     >>> r.shape
     (10,)
     """
+
+    if dtype is None and formats is None:
+        raise TypeError("fromfile() needs a 'dtype' or 'formats' argument")
 
     if (shape is None or shape == 0):
         shape = (-1,)