Reproduce empty cell issue #53

tests/test_preserve_empty_cells.py

@@ -0,0 +1,32 @@
+import pytest
+from testfixtures import compare
+from nbformat.v4.nbbase import new_notebook, new_code_cell, new_markdown_cell
+import jupytext
+
+jupytext.file_format_version.FILE_FORMAT_VERSION = {}
+
+
+@pytest.mark.parametrize('blank_lines', range(1, 6))
+def test_file_with_blank_lines(blank_lines):
+    py_script = """# Markdown cell{0}
+# Another one{0}
+""".format('\n'.join([''] * blank_lines))
+
+    notebook = jupytext.reads(py_script, ext='.py')
+    py_script2 = jupytext.writes(notebook, ext='.py')
+    compare(py_script, py_script2)
+
+
+@pytest.mark.skip(reason='#53')
+@pytest.mark.parametrize('blank_cells', range(1, 3))
+def test_notebook_with_empty_cells(blank_cells):
+    notebook = new_notebook(cells=[new_markdown_cell('markdown cell one')] +
+                                  [new_code_cell('')] * blank_cells +
+                                  [new_markdown_cell('markdown cell two')] +
+                                  [new_code_cell('')] * blank_cells,
+                            metadata={'main_language': 'python'})
+
+    script = jupytext.writes(notebook, ext='.py')
+    notebook2 = jupytext.reads(script, ext='.py')
+
+    compare(notebook, notebook2)