Move ODFReader get_sheet exception testing code to its own function

that ends with _raises

Author: detrout

pandas/tests/io/test_excel.py

@@ -2567,18 +2567,24 @@ def test_get_sheet(self):
         pth = os.path.join(self.dirpath, 'datatypes.ods')
         book = _ODFReader(pth)
 
+        assert len(book.sheet_names) == 1
+        assert book.sheet_names == ['Sheet1']
+
+    def test_get_sheet_raises(self):
+        from pandas.io.excel._odfreader import _ODFReader
+
+        pth = os.path.join(self.dirpath, 'datatypes.ods')
+        book = _ODFReader(pth)
+
         with pytest.raises(ValueError):
-            book.get_sheet(3.14)
+            book._get_sheet(3.14)
 
         with pytest.raises(ValueError):
             book.get_sheet_by_name("Invalid Sheet 77")
 
         with pytest.raises(IndexError):
             book.get_sheet_by_index(-33)
 
-        assert len(book.sheet_names) == 1
-        assert book.sheet_names == ['Sheet1']
-
     def test_read_types(self):
         """Make sure we read ODF data types correctly
         """