fix(latex-renderer): rendering of package options

Rendering package options with string delimiters leads to LaTeX errors,
e.g., when `render_strikethrough` activates the 'ulem' package with
option 'normalem', the rendered LaTeX should read
`\usepackage[normalem]{ulem}` rather than
`\usepackage['normalem']{ulem}` as it previously did. This patch fixes
that.

NB: Too keep the implementation simple (and as it has not shown adverse
side-effects when using pdflatex), the generated LaTeX for an added
package listings without options is now \usepackage[]{listings} rather
than \usepackage{listings}.

mistletoe/latex_renderer.py

@@ -165,8 +165,8 @@ def render_line_break(token):
         return '\n' if token.soft else '\\newline\n'
 
     def render_packages(self):
-        pattern = '\\usepackage{options}{{{package}}}\n'
-        return ''.join(pattern.format(options=options or '', package=package)
+        pattern = '\\usepackage[{options}]{{{package}}}\n'
+        return ''.join(pattern.format(options=', '.join(options) or '', package=package)
                          for package, options in self.packages.items())
 
     def render_document(self, token):

test/test_latex_renderer.py

@@ -1,6 +1,5 @@
 from unittest import TestCase, mock
 from parameterized import parameterized
-import mistletoe.latex_renderer
 from mistletoe.latex_renderer import LaTeXRenderer
 from mistletoe import markdown
 
@@ -132,6 +131,14 @@ def test_document(self):
                   '\\end{document}\n')
         self._test_token('Document', expected, footnotes={})
 
+    def test_packages(self):
+        self.renderer.packages = {
+            'ulem': ['normalem'],
+            'hyperref': [],
+        }
+        self.assertEqual(self.renderer.render_packages(),
+                         '\\usepackage[normalem]{ulem}\n' +
+                         '\\usepackage[]{hyperref}\n')
 
 class TestHtmlEntity(TestCase):
     def test_html_entity(self):
@@ -151,7 +158,7 @@ def test_footnote_image(self):
         from mistletoe import Document
         raw = ['![alt][foo]\n', '\n', '[foo]: bar "title"\n']
         expected = ('\\documentclass{article}\n'
-                  '\\usepackage{graphicx}\n'
+                  '\\usepackage[]{graphicx}\n'
                   '\\begin{document}\n'
                   '\n'
                   '\n\\includegraphics{bar}\n'
@@ -163,7 +170,7 @@ def test_footnote_link(self):
         from mistletoe import Document
         raw = ['[name][key]\n', '\n', '[key]: target\n']
         expected = ('\\documentclass{article}\n'
-                  '\\usepackage{hyperref}\n'
+                  '\\usepackage[]{hyperref}\n'
                   '\\begin{document}\n'
                   '\n'
                   '\\href{target}{name}'