Merge 75d887f into e6d1a9e

CHANGES.rst

@@ -187,6 +187,9 @@ astropy.io.misc
 astropy.io.fits
 ^^^^^^^^^^^^^^^
 
+- Override ``HDUList.copy()`` to return a copy instead
+  of ``list``. [#7218]
+
 astropy.io.registry
 ^^^^^^^^^^^^^^^^^^^
 

astropy/io/fits/hdu/hdulist.py

@@ -510,6 +510,27 @@ def fileinfo(self, index):
 
         return output
 
+    def copy(self, deep=True):
+        """
+        Return a copy of the object.
+
+        Parameters
+        ----------
+        deep : bool (default=True)
+            Whether to create a deep copy or a shallow copy.
+
+        Returns
+        -------
+        self : HDUList
+            A copy of this :class:`HDUList` object.
+
+        """
+
+        if deep:
+            return HDUList([hdu.copy() for hdu in self])
+        else:
+            return self[:]
+
     def pop(self, index=-1):
         # Make sure that HDUs are loaded before attempting to pop
         self.readall()

astropy/io/fits/tests/test_hdulist.py

@@ -376,6 +376,35 @@ def test_file_like_3(self):
         info = [(0, 'PRIMARY', 1, 'PrimaryHDU', 5, (100,), 'int32', '')]
         assert fits.info(self.temp('tmpfile.fits'), output=False) == info
 
+    def test_copy_list(self):
+        """
+        Tests that HDUList.copy() returns a shallow copy (regression test
+        for ticket:7211).
+        """
+
+        n = np.arange(10.0)
+        primary_hdu = fits.PrimaryHDU(n)
+        hdu = fits.ImageHDU(n)
+        hdul = fits.HDUList([primary_hdu, hdu])
+
+        shallow_copy = hdul.copy(deep=False)
+        deep_copy = hdul.copy(deep=True)
+
+        assert isinstance(shallow_copy, fits.HDUList)
+        assert isinstance(deep_copy, fits.HDUList)
+
+        assert shallow_copy is not hdul
+        assert shallow_copy[0] is hdul[0]
+        assert shallow_copy[1] is hdul[1]
+
+        assert deep_copy is not hdul
+        assert deep_copy[0] is not hdul[0]
+        assert deep_copy[1] is not hdul[1]
+        assert deep_copy[0].header == hdul[0].header
+        assert deep_copy[1].header == hdul[1].header
+        assert (deep_copy[0].data == hdul[0].data).all()
+        assert (deep_copy[1].data == hdul[1].data).all()
+
     def test_new_hdu_extname(self):
         """
         Tests that new extension HDUs that are added to an HDUList can be