BUG: ticket #1793, fix failing npyio test under py3k. Thanks to Derek…

… Homeier.

numpy/lib/npyio.py

@@ -765,6 +765,7 @@ def split_line(line):
             # End of lines reached
             first_line = ''
             first_vals = []
+            warnings.warn('loadtxt: Empty input file: "%s"' % fname)
         N = len(usecols or first_vals)
 
         dtype_types, packing = flatten_dtype(dtype)
@@ -1299,8 +1300,10 @@ def genfromtxt(fname, dtype=float, comments='#', delimiter=None,
                     first_line = asbytes('').join(first_line.split(comments)[1:])
             first_values = split_line(first_line)
     except StopIteration:
-        # might want to return empty array instead of raising error.
-        raise IOError('End-of-file reached before encountering data.')
+        # return an empty array if the datafile is empty
+        first_line = asbytes('')
+        first_values = []
+        warnings.warn('genfromtxt: Empty input file: "%s"' % fname)
 
     # Should we take the first values as names ?
     if names is True:

numpy/lib/tests/test_io.py

@@ -428,6 +428,7 @@ def test_3d_shaped_dtype(self):
         assert_array_equal(x, a)
 
     def test_empty_file(self):
+        warnings.filterwarnings("ignore", message="loadtxt: Empty input file:")
         c = StringIO()
         x = np.loadtxt(c)
         assert_equal(x.shape, (0,))
@@ -987,11 +988,17 @@ def test_usecols_with_named_columns(self):
                              usecols=('a', 'c'), **kwargs)
         assert_equal(test, ctrl)
 
-
     def test_empty_file(self):
-        "Test that an empty file raises the proper exception"
-        data = StringIO()
-        assert_raises(IOError, np.ndfromtxt, data)
+        "Test that an empty file raises the proper warning."
+        warn_ctx = WarningManager()
+        warn_ctx.__enter__()
+        try:
+            warnings.filterwarnings("ignore", message="genfromtxt: Empty input file:")
+            data = StringIO()
+            test = np.genfromtxt(data)
+            assert_equal(test, np.array([]))
+        finally:
+            warn_ctx.__exit__()
 
 
     def test_fancy_dtype_alt(self):