Add back doctest

Author: kwankyu

src/sage/plot/graphics.py

@@ -2419,7 +2419,11 @@ def _matplotlib_tick_formatter(self, subplot, base=(10, 10),
                     LogFormatterMathtext(base=base[0])(n, pos).replace(
                         "\\mathdefault", ""))
             else:
-                x_formatter = FuncFormatter(lambda n, pos: '$%s$' % latex(n))
+                # circumvent the problem of symbolic tick values (trac #34693)
+                if isinstance(x_locator, FixedLocator):
+                    x_formatter = FixedFormatter(['$%s$' % latex(n) for n in x_locator.locs])
+                else:
+                    x_formatter = FuncFormatter(lambda n, pos: '$%s$' % latex(n))
         elif isinstance(x_formatter, (list, tuple)):
             if (not isinstance(ticks[0], (list, tuple)) or
                     len(ticks[0]) != len(x_formatter)):

src/sage/plot/plot.py

@@ -1741,9 +1741,14 @@ def b(n): return lambda x: bessel_J(n, x) + 0.5*(n-1)
 
     ::
 
-        sage: plot(2*x+1,(x,0,5),ticks=[[0,1,e,pi,sqrt(20)],2],tick_formatter="latex") # not tested (broken with matplotlib 3.6)
+        sage: plot(2*x + 1,(x, 0, 5), ticks=[[0, 1, e, pi, sqrt(20)], 2], tick_formatter="latex")
         Graphics object consisting of 1 graphics primitive
 
+    .. PLOT::
+
+        g = plot(2*x + 1, (x, 0, 5), ticks=[[0, 1, e, pi, sqrt(20)], 2], tick_formatter="latex")
+        sphinx_plot(g)
+
     This is particularly useful when setting custom ticks in multiples of `pi`.
 
     ::