Use batchmode in latex_to_png_dvipng

Latex is running into some unrelated error on my system, and making an
unseen prompt for output, which results in a test hanging. This turns
the hang into a failure.

IPython/lib/latextools.py

@@ -1,251 +1,251 b''
 # -*- coding: utf-8 -*-
 """Tools for handling LaTeX.
 
 Authors:
 
 * Brian Granger
 """
 #-----------------------------------------------------------------------------
 # Copyright (C) 2010 IPython Development Team.
 #
 # Distributed under the terms of the Modified BSD License.
 #
 # The full license is in the file COPYING.txt, distributed with this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 from io import BytesIO
 from base64 import encodestring
 import os
 import tempfile
 import shutil
 import subprocess
 
 from IPython.utils.process import find_cmd, FindCmdError
 from IPython.config.configurable import SingletonConfigurable
 from IPython.utils.traitlets import List, CBool, CUnicode
 from IPython.utils.py3compat import bytes_to_str
 
 #-----------------------------------------------------------------------------
 # Tools
 #-----------------------------------------------------------------------------
 
 
 class LaTeXTool(SingletonConfigurable):
     """An object to store configuration of the LaTeX tool."""
 
     backends = List(
         CUnicode, ["matplotlib", "dvipng"],
         help="Preferred backend to draw LaTeX math equations. "
         "Backends in the list are checked one by one and the first "
         "usable one is used.  Note that `matplotlib` backend "
         "is usable only for inline style equations.  To draw  "
         "display style equations, `dvipng` backend must be specified. ",
         # It is a List instead of Enum, to make configuration more
         # flexible.  For example, to use matplotlib mainly but dvipng
         # for display style, the default ["matplotlib", "dvipng"] can
         # be used.  To NOT use dvipng so that other repr such as
         # unicode pretty printing is used, you can use ["matplotlib"].
         config=True)
 
     use_breqn = CBool(
         True,
         help="Use breqn.sty to automatically break long equations. "
         "This configuration takes effect only for dvipng backend.",
         config=True)
 
     packages = List(
         ['amsmath', 'amsthm', 'amssymb', 'bm'],
         help="A list of packages to use for dvipng backend. "
         "'breqn' will be automatically appended when use_breqn=True.",
         config=True)
 
     preamble = CUnicode(
         help="Additional preamble to use when generating LaTeX source "
         "for dvipng backend.",
         config=True)
 
 
 def latex_to_png(s, encode=False, backend=None, wrap=False):
     """Render a LaTeX string to PNG.
 
     Parameters
     ----------
     s : str
         The raw string containing valid inline LaTeX.
     encode : bool, optional
         Should the PNG data bebase64 encoded to make it JSON'able.
     backend : {matplotlib, dvipng}
         Backend for producing PNG data.
     wrap : bool
         If true, Automatically wrap `s` as a LaTeX equation.
 
     None is returned when the backend cannot be used.
 
     """
     allowed_backends = LaTeXTool.instance().backends
     if backend is None:
         backend = allowed_backends[0]
     if backend not in allowed_backends:
         return None
     if backend == 'matplotlib':
         f = latex_to_png_mpl
     elif backend == 'dvipng':
         f = latex_to_png_dvipng
     else:
         raise ValueError('No such backend {0}'.format(backend))
     bin_data = f(s, wrap)
     if encode and bin_data:
         bin_data = encodestring(bin_data)
     return bin_data
 
 
 def latex_to_png_mpl(s, wrap):
     try:
         from matplotlib import mathtext
     except ImportError:
         return None
 
     if wrap:
         s = '${0}$'.format(s)
     mt = mathtext.MathTextParser('bitmap')
     f = BytesIO()
     mt.to_png(f, s, fontsize=12)
     return f.getvalue()
 
 
 def latex_to_png_dvipng(s, wrap):
     try:
         find_cmd('latex')
         find_cmd('dvipng')
     except FindCmdError:
         return None
     try:
         workdir = tempfile.mkdtemp()
         tmpfile = os.path.join(workdir, "tmp.tex")
         dvifile = os.path.join(workdir, "tmp.dvi")
         outfile = os.path.join(workdir, "tmp.png")
 
         with open(tmpfile, "w") as f:
             f.writelines(genelatex(s, wrap))
 
         with open(os.devnull, 'w') as devnull:
             subprocess.check_call(
-                ["latex", "-halt-on-error", tmpfile], cwd=workdir,
-                stdout=devnull, stderr=devnull)
+                ["latex", "-halt-on-error", "-interaction", "batchmode", tmpfile],
+                cwd=workdir, stdout=devnull, stderr=devnull)
 
             subprocess.check_call(
                 ["dvipng", "-T", "tight", "-x", "1500", "-z", "9",
                  "-bg", "transparent", "-o", outfile, dvifile], cwd=workdir,
                 stdout=devnull, stderr=devnull)
 
         with open(outfile, "rb") as f:
             return f.read()
     finally:
         shutil.rmtree(workdir)
 
 
 def kpsewhich(filename):
     """Invoke kpsewhich command with an argument `filename`."""
     try:
         find_cmd("kpsewhich")
         proc = subprocess.Popen(
             ["kpsewhich", filename],
             stdout=subprocess.PIPE, stderr=subprocess.PIPE)
         (stdout, stderr) = proc.communicate()
         return stdout.strip()
     except FindCmdError:
         pass
 
 
 def genelatex(body, wrap):
     """Generate LaTeX document for dvipng backend."""
     lt = LaTeXTool.instance()
     breqn = wrap and lt.use_breqn and kpsewhich("breqn.sty")
     yield r'\documentclass{article}'
     packages = lt.packages
     if breqn:
         packages = packages + ['breqn']
     for pack in packages:
         yield r'\usepackage{{{0}}}'.format(pack)
     yield r'\pagestyle{empty}'
     if lt.preamble:
         yield lt.preamble
     yield r'\begin{document}'
     if breqn:
         yield r'\begin{dmath*}'
         yield body
         yield r'\end{dmath*}'
     elif wrap:
         yield '$${0}$$'.format(body)
     else:
         yield body
     yield r'\end{document}'
 
 
 _data_uri_template_png = """<img src="data:image/png;base64,%s" alt=%s />"""
 
 def latex_to_html(s, alt='image'):
     """Render LaTeX to HTML with embedded PNG data using data URIs.
 
     Parameters
     ----------
     s : str
         The raw string containing valid inline LateX.
     alt : str
         The alt text to use for the HTML.
     """
     base64_data = bytes_to_str(latex_to_png(s, encode=True), 'ascii')
     if base64_data:
         return _data_uri_template_png  % (base64_data, alt)
 
 
 # From matplotlib, thanks to mdboom. Once this is in matplotlib releases, we
 # will remove.
 def math_to_image(s, filename_or_obj, prop=None, dpi=None, format=None):
     """
     Given a math expression, renders it in a closely-clipped bounding
     box to an image file.
 
     *s*
        A math expression.  The math portion should be enclosed in
        dollar signs.
 
     *filename_or_obj*
        A filepath or writable file-like object to write the image data
        to.
 
     *prop*
        If provided, a FontProperties() object describing the size and
        style of the text.
 
     *dpi*
        Override the output dpi, otherwise use the default associated
        with the output format.
 
     *format*
        The output format, eg. 'svg', 'pdf', 'ps' or 'png'.  If not
        provided, will be deduced from the filename.
     """
     from matplotlib import figure
     # backend_agg supports all of the core output formats
     from matplotlib.backends import backend_agg
     from matplotlib.font_manager import FontProperties
     from matplotlib.mathtext import MathTextParser
 
     if prop is None:
         prop = FontProperties()
 
     parser = MathTextParser('path')
     width, height, depth, _, _ = parser.parse(s, dpi=72, prop=prop)
 
     fig = figure.Figure(figsize=(width / 72.0, height / 72.0))
     fig.text(0, depth/height, s, fontproperties=prop)
     backend_agg.FigureCanvasAgg(fig)
     fig.savefig(filename_or_obj, dpi=dpi, format=format)
 
     return depth