epub2md/tests/test_math.py

import pytest
from lxml import etree

from conftest import PNG, SVG, Book, Doc
from epub2md.mathml import Unsupported, mathml_to_tex, portable_tex

M = 'xmlns="http://www.w3.org/1998/Math/MathML"'


def tex(xml: str) -> str:
    return mathml_to_tex(etree.fromstring(f"<math {M}>{xml}</math>"))


@pytest.mark.parametrize(
    ("xml", "expected"),
    [
        ("<mfrac><mi>a</mi><mi>b</mi></mfrac>", r"\frac{a}{b}"),
        ("<msup><mi>x</mi><mn>2</mn></msup>", "x^{2}"),
        ("<msub><mi>a</mi><mi>i</mi></msub>", "a_{i}"),
        ("<msubsup><mi>x</mi><mi>i</mi><mn>2</mn></msubsup>", "x_{i}^{2}"),
        ("<msqrt><mi>x</mi></msqrt>", r"\sqrt{x}"),
        ("<mroot><mi>x</mi><mn>3</mn></mroot>", r"\sqrt[3]{x}"),
        ("<munderover><mo>∑</mo><mrow><mi>i</mi><mo>=</mo><mn>1</mn></mrow><mi>n</mi></munderover><msub><mi>a</mi><mi>i</mi></msub>",
         r"\sum_{i = 1}^{n} a_{i}"),
        ("<mi>α</mi><mo>≤</mo><mi>β</mi>", r"\alpha \leq \beta"),
        ("<mover><mi>x</mi><mo>^</mo></mover>", r"\hat{x}"),
        ("<mi mathvariant='double-struck'>R</mi>", r"\mathbb{R}"),
        ("<mtext>für alle</mtext>", r"\text{für alle}"),
        ("<mrow><mo>(</mo><mtable><mtr><mtd><mn>1</mn></mtd><mtd><mn>0</mn></mtd></mtr>"
         "<mtr><mtd><mn>0</mn></mtd><mtd><mn>1</mn></mtd></mtr></mtable><mo>)</mo></mrow>",
         r"\left( \begin{matrix} 1 & 0 \\ 0 & 1 \end{matrix} \right)"),
    ],
)
def test_mathml_to_tex(xml, expected):
    assert tex(xml) == expected


def test_tex_annotation_is_preferred():
    xml = ('<semantics><mi>x</mi><annotation encoding="application/x-tex">\\mathbf{x}</annotation></semantics>')
    assert tex(xml) == r"\mathbf{x}"


@pytest.mark.parametrize("xml", ["<menclose><mi>x</mi></menclose>", "<mmultiscripts><mi>x</mi></mmultiscripts>",
                                 "<mtable><mlabeledtr><mtd>1</mtd></mlabeledtr></mtable>"])
def test_unsupported_mathml_raises(xml):
    with pytest.raises(Unsupported):
        tex(xml)


BODY = (
    "<h1>Formeln</h1>"
    f'<p>Inline <math {M}><mfrac><mi>a</mi><mi>b</mi></mfrac></math> im Satz.</p>'
    f'<div class="equation"><math {M} display="block"><msup><mi>x</mi><mn>2</mn></msup></math> <span>(3.7)</span></div>'
    f'<p>Unbekannt: <math {M}><menclose notation="box"><mi>z</mi></menclose></math></p>'
    '<p>SVG: <span class="math"><img src="f.svg" alt="Formel 1"/></span></p>'
    '<p>Bild ohne TeX: <span class="equation"><img src="eq.png" alt="Summe"/></span></p>'
    '<p>Bild mit TeX: <span class="InlineEquation"><img src="eq2.png" alt="$$a &amp;amp; b \\leq c$$"/></span></p>'
)


def math_book() -> Book:
    return Book(docs=[Doc("m.xhtml", BODY)], media={"f.svg": SVG, "eq.png": PNG, "eq2.png": PNG})


def test_math_auto(convert):
    run = convert(math_book())
    text = run.chapter("001")
    assert r"Inline $\frac{a}{b}$ im Satz." in text
    assert "$$\nx^{2}\n$$" in text
    assert "(3.7)" in text  # equation number visible
    assert "<math" in text and "menclose" in text  # unsupported MathML kept, not lost
    assert "![Formel 1](../media/images/" in text  # SVG formula stays SVG
    assert "![Summe](../media/images/" in text
    assert r"$a & b \leq c$" in text  # TeX from alt, double escaping repaired
    codes = [w["code"] for w in run.report["warnings"]]
    assert "mathml-kept" in codes and "formula-image" in codes
    svgs = [m for m in run.report["media"]["files"] if m["file"].endswith(".svg")]
    assert svgs and svgs[0]["media_type"] == "image/svg+xml"


def test_math_tex_mode_uses_backslash_delimiters(convert):
    text = convert(math_book(), "--math", "tex").chapter("001")
    assert r"\(\frac{a}{b}\)" in text
    assert "\\[\nx^{2}\n\\]" in text
    assert "$" not in text.replace("\\$", "")


def test_math_mathml_mode_keeps_mathml(convert):
    text = convert(math_book(), "--math", "mathml").chapter("001")
    assert '<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mi>a</mi><mi>b</mi></mfrac></math>' in text
    assert "frac{" not in text


def test_math_image_mode(convert):
    run = convert(math_book(), "--math", "image")
    text = run.chapter("001")
    assert text.count("![") == 3  # svg + both formula images
    assert "<math" in text  # pure MathML without image is not lost
    assert any(w["code"] == "mathml-no-image" for w in run.report["warnings"])


def test_svg_file_formula_is_reported_as_svg(convert):
    """QA-F3: <img src="*.svg"> inside a formula container is an SVG formula in the report."""
    report = convert(math_book()).report
    origins = {f["origin"] for f in report["formulas"]["items"]}
    assert "svg" in origins


def test_book_readme_suggests_mathml_for_pandoc_only_with_formulas(convert):
    run = convert(math_book())
    readme = (run.out / "README.md").read_text(encoding="utf-8")
    assert "## Weiterverarbeitung" in readme and "epub2md_merge.py" in readme
    assert "--mathml" in readme
    pandoc_lines = [ln for ln in readme.splitlines() if ln.startswith("pandoc ")]
    assert pandoc_lines and all("--mathml" in ln for ln in pandoc_lines)  # EPUB too, else TeX stays text (QA3-04)
    plain = convert(Book(docs=[Doc("a.xhtml", "<h1>A</h1><p>Text</p>")]))
    plain_readme = (plain.out / "README.md").read_text(encoding="utf-8")
    assert "## Weiterverarbeitung" in plain_readme and "--mathml" not in plain_readme


@pytest.mark.parametrize("tex,expected", [
    (r'\mbox{gr\"un}, \text{F\"{u}r}', r"\mbox{grün}, \text{Für}"),
    (r'\text{ f{\"u}r } j', r"\text{ f{ü}r } j"),  # braces stay balanced
    (r"{\mathscr L}(A,b)={{\O }}", r"{\mathscr L}(A,b)={{\emptyset }}"),
    (r"M\cap N=\text{\O }", r"M\cap N=\emptyset"),
    (r"\Omega\neq\O", r"\Omega\neq\emptyset"),
    (r"\begin{array}{@{}l@{\qquad \quad }l@{}} a & b\end{array}", r"\begin{array}{ll} a & b\end{array}"),
    (r"\arraycolsep8pt\begin{array}{c@{\,}r} x\end{array}", r"\begin{array}{cr} x\end{array}"),
    (r"a & =&\displaystyle b, \\ & \vdots &\displaystyle \\ c", r"a & =&\displaystyle b, \\ & \vdots &\\ c"),
    (r"\frac{a}{b}+\{x\}", r"\frac{a}{b}+\{x\}"),
])
def test_publisher_tex_is_made_portable(tex, expected):
    """Pandoc's texmath rejects \\", \\O, @{…} and \\arraycolsep (Springer alt texts, QA3-06)."""
    assert portable_tex(tex) == expected