Added regression test for single_reference=True bug

Author: astrofrog

tests/baseline/test_single_reference.fits

@@ -152,5 +152,15 @@ def test_absolute_tolerance():
     return np.ones((3, 4)) * 1.6 + 1.4
 
 
+@pytest.mark.array_compare(
+        reference_dir=reference_dir,
+        atol=1.5,
+        file_format='fits',
+        single_reference=True)
+@pytest.mark.parametrize('spam', ('egg', 'bacon'))
+def test_single_reference(spam):
+    return np.ones((3, 4)) * 1.6 + 1.4
+
+
 def test_nofile():
     pass