test_jupytext_nbconvert_round_trip.py

import pytest
import jupytext
from jupytext.header import header_to_metadata_and_cell
from .utils import list_notebooks, requires_nbconvert


@requires_nbconvert
@pytest.mark.parametrize('md_file', list_notebooks('md', skip='jupytext'))
def test_markdown_jupytext_nbconvert_is_identity(md_file):
    """Test that a Markdown file, converted to a notebook, then
    exported back to Markdown with nbconvert, yields the original file"""

    with open(md_file) as fp:
        md_org = fp.read()

    nb = jupytext.reads(md_org, 'md')
    import nbconvert
    md_nbconvert, _ = nbconvert.export(nbconvert.MarkdownExporter, nb)

    # Our expectations
    md_expected = md_org.splitlines()
    # #region and #endregion comments are removed
    md_expected = [line for line in md_expected if line not in ['<!-- #region -->', '<!-- #endregion -->']]
    # language is not inserted by nbconvert
    md_expected = ['```' if line.startswith('```') else line for line in md_expected]
    # nbconvert inserts no empty line after the YAML header (which is in a Raw cell)
    md_expected = '\n'.join(md_expected).replace('---\n\n', '---\n') + '\n'

    # an extra blank line is inserted before code cells
    md_nbconvert = md_nbconvert.replace('\n\n```', '\n```')

    jupytext.compare.compare(md_nbconvert, md_expected)


@requires_nbconvert
@pytest.mark.parametrize('nb_file', list_notebooks(skip='(html|magic)'))
def test_jupytext_markdown_similar_to_nbconvert(nb_file):
    """Test that the nbconvert export for a notebook matches Jupytext's one"""

    nb = jupytext.read(nb_file)

    # Remove cell outputs and metadata
    for cell in nb.cells:
        cell.outputs = []
        cell.execution_count = None
        cell.metadata = {}

    md_jupytext = jupytext.writes(nb, fmt='md')

    import nbconvert
    md_nbconvert, _ = nbconvert.export(nbconvert.MarkdownExporter, nb)

    # our expectations

    # nbconvert file has no YAML header
    md_jupytext_lines = md_jupytext.splitlines()
    _, _, raw_cell, pos = header_to_metadata_and_cell(md_jupytext_lines, '')
    md_jupytext = '\n'.join(md_jupytext_lines[pos:]) + '\n'
    if raw_cell is not None:
        md_jupytext = raw_cell.source + '\n\n' + md_jupytext

    # region comments are not in nbconvert
    md_jupytext = md_jupytext.replace('<!-- #region -->\n', '').replace('<!-- #endregion -->\n', '')

    # Jupytext uses HTML comments to keep track of raw cells
    md_jupytext = (md_jupytext
                   .replace('\n<!-- #raw -->\n', '')
                   .replace('<!-- #raw -->\n', '')
                   .replace('\n<!-- #endraw -->\n', ''))

    # nbconvert file may start with an empty line
    md_jupytext = md_jupytext.lstrip('\n')
    md_nbconvert = md_nbconvert.lstrip('\n')

    # Jupytext may not always have two blank lines between cells like Jupyter nbconvert
    md_jupytext = md_jupytext.replace('\n\n\n', '\n\n')
    md_nbconvert = md_nbconvert.replace('\n\n\n', '\n\n')

    jupytext.compare.compare(md_nbconvert, md_jupytext)