Cleanup; add unicode test

common/lib/calc/preview.py

@@ -136,6 +136,9 @@ def render_power(children):
 
     If you have 'a^(b+c)' don't include that last set of parens ('a^{b+c}').
     """
+    if len(children) == 1:
+        return children[0]
+
     children_latex = [k.latex for k in children if k.latex != "^"]
     children_latex[-1] = children[-1].sans_parens
 
@@ -237,13 +240,13 @@ def render_atom(children):
     """
     parens = None
     if children[0].latex in "([{":
+        # then len(children) == 3
         parens = children[0].latex
-        children = children[1:-1]
-    tall = any(k.tall for k in children)
+        children = [children[1]]
     return LatexRendered(
-        "".join(k.latex for k in children),
+        children[0].latex,
         parens,
-        tall
+        children[0].tall
     )
 
 
@@ -281,8 +284,8 @@ def latex_preview(math_expr, variables=(), functions=(), case_sensitive=False):
         'sum': render_sum
     }
 
-    bs = "\\"
-    wrap_escaped_strings = lambda s: LatexRendered(s.replace(bs, bs * 2))
+    bksh = "\\"
+    wrap_escaped_strings = lambda s: LatexRendered(s.replace(bksh, bksh * 2))
 
     output = thing.handle_tree(render_actions, wrap_escaped_strings)
     return output.latex

common/lib/calc/tests/test_preview.py

@@ -42,7 +42,12 @@ class LatexRenderedTest(PreviewTestUtility):
         Helper method to test the way parens are wrapped.
         """
         obj = preview.LatexRendered(math, parens=parens, tall=tall)
-        self.assert_latex_rendered(obj, tall=tall, latex=with_parens, sans_parens=math)
+        self.assert_latex_rendered(
+            obj,
+            tall=tall,
+            latex=with_parens,
+            sans_parens=math
+        )
 
     def test_parens(self):
         """ Test curvy parens. """
@@ -107,6 +112,18 @@ class RenderMethodsTest(PreviewTestUtility):
         out = _call_render_method(render_variable, ['x'])
         self.assert_latex_rendered(out, latex='x')
 
+    def test_variable_unicode(self):
+        """
+        Simple valid unicode variables should pass through as well.
+
+        Note: it isn't supported right now in the rest of the code (esp. the
+        way we have set up pyparsing), but when it is, this should work.
+        """
+        var = "✖"
+        render_variable = preview.variable_closure([var], lambda x: x.lower())
+        out = _call_render_method(render_variable, [var])
+        self.assert_latex_rendered(out, latex=var)
+
     def test_greek(self):
         """ Variable names that are greek should be formatted accordingly. """
         render_variable = preview.variable_closure(['pi'], lambda x: x.lower())