Adding tests and another line normalization for stderr.

IPython/testing/tests/test_tools.py

@@ -88,3 +88,27 b' class TestAssertPrints(unittest.TestCase):'
                 print b"ghi"
         
         self.assertRaises(AssertionError, func)
+
+
+class Test_ipexec_validate(unittest.TestCase, tt.TempFileMixin):
+    def test_main_path(self):
+        """Test with only stdout results.
+        """
+        self.mktmp("print('A')\n"
+                   "print('B')\n"
+                   )
+        out = "A\nB"
+        tt.ipexec_validate(self.fname, out)
+
+    def test_exception_path(self):
+        """Test exception path in exception_validate.
+        """
+        self.mktmp("from __future__ import print_function\n"
+                   "import sys\n"
+                   "print('A')\n"
+                   "print('B')\n"
+                   "print('C', file=sys.stderr)\n"
+                   "print('D', file=sys.stderr)\n"
+                   )
+        out = "A\nB"
+        tt.ipexec_validate(self.fname, expected_out=out, expected_err="C\nD")

IPython/testing/tools.py

@@ -235,7 +235,7 b" def ipexec_validate(fname, expected_out, expected_err='',"
     # more informative than simply having an empty stdout.
     if err:
         if expected_err:
-            nt.assert_equal(err.strip(), expected_err.strip())
+            nt.assert_equal("\n".join(err.strip().splitlines()), "\n".join(expected_err.strip().splitlines()))
         else:
             raise ValueError('Running file %r produced error: %r' %
                              (fname, err))