TST: added regression test for io.readsav issue with invalid pointers.

Author: astrofrog

scipy/io/tests/data/invalid_pointer.sav

@@ -1,7 +1,7 @@
 from __future__ import division, print_function, absolute_import
 
 from os import path
-
+from warnings import catch_warnings
 
 DATA_PATH = path.join(path.dirname(__file__), 'data')
 
@@ -408,12 +408,27 @@ def test_description(self):
 
 
 def test_null_pointer():
-    """
-    Regression test for null pointers.
-    """
+    # Regression test for null pointers.
     s = readsav(path.join(DATA_PATH, 'null_pointer.sav'), verbose=False)
     assert_identical(s.point, None)
     assert_identical(s.check, np.int16(5))
 
+
+def test_invalid_pointer():
+    # Regression test for invalid pointers (gh-4613).
+
+    # In some files in the wild, pointers can sometimes refer to a heap
+    # variable that does not exist. In that case, we now gracefully fail for
+    # that variable and replace the variable with None and emit a warning.
+    # Since it's difficult to artificially produce such files, the file used
+    # here has been edited to force the pointer reference to be invalid.
+    with catch_warnings(record=True) as w:
+        s = readsav(path.join(DATA_PATH, 'invalid_pointer.sav'), verbose=False)
+    assert_(len(w) == 1)
+    assert_(str(w[0].message) == ("Variable referenced by pointer not found in "
+                                  "heap: variable will be set to None"))
+    assert_identical(s['a'], np.array([None, None]))
+
+
 if __name__ == "__main__":
     run_module_suite()