Plotly graphs not rendered in extras data

I'm trying to add Plotly graphs in my test report, but they are somehow not visible when I open the report (either Chrome or Edge).

To reproduce, two files need to be created: conftest.py and test_dummy_plot.py. Bellow, the content of those two files, respectively:

import pytest
import pytest_html


@pytest.mark.hookwrapper
def pytest_runtest_makereport(item, call):
    outcome = yield
    report = outcome.get_result()
    if call.when == 'call':
        extras = getattr(report, 'extras', [])
        fig = item.user_properties[0]
        c = fig.to_html(full_html=False, div_id='my_plot', include_plotlyjs='cdn')

        fig.write_html('my_plot.html', include_plotlyjs='cdn')  # export the figure to HTML to validate its content (just for debugging).

        extras.append(pytest_html.extras.html("<div>Additional HTML 1</div>"))  # only for debugging.
        extras.append(pytest_html.extras.html(c))
        extras.append(pytest_html.extras.html("<div>Additional HTML 2</div>"))  # only for debugging.
        report.extras = extras

import plotly.graph_objects as go
import pytest
from plotly.subplots import make_subplots


def test_example(request: pytest.FixtureRequest):
    fig = make_subplots()
    fig.add_trace(go.Scatter(x=[1, 2, 3, 4], y=[1, 2, 4, 8]))
    request.node.user_properties.append(fig)

Now, when running the test by invoking python -m pytest --html=report.html --self-contained-html . in the folder containing those two files, two new files are generated:

• my_plot.html
• report.html

Here is a screenshot of the plot itself, when opening my_plot.html:

And now, a screenshot of the test report, when opening report.html:

We can see that the plot is not rendered, even if present in the HTML file, as depicted in the following screenshot:

I'm not really sure why it is not rendered properly. I raised a question on StackOverflow and it seems that a solution exists, but I don't know how to integrate it properly.

Start with the provided conftest.py and test_dummy_plot.py, then run python -m pytest --html=report.html --self-contained-html . to compare report.html with the standalone my_plot.html. Trace how the Plotly HTML is embedded in report.html and use the linked StackOverflow solution as context. Done means the Plotly graph renders in the generated pytest report in Chrome and Edge.