Be more precise in test marking (use xfail on broken test).

pymbolic/__init__.py

@@ -43,7 +43,7 @@ def grad(expression, variables):
 
 def jacobian(expression_list, variables):
     return [grad(expr, variables) for expr in expression_list]
-    
+
 def laplace(expression, variables):
     return sum(differentiate(differentiate(expression,var), var) for var in variables)
 
@@ -52,7 +52,7 @@ def laplace(expression, variables):
 
 class VectorFunction:
     def __init__(self, function_list, variables=[]):
-        self.FunctionList = [pymbolic.compile(expr, variables=variables) 
+        self.FunctionList = [pymbolic.compile(expr, variables=variables)
                              for expr in function_list]
 
     def __call__(self, x):

test/test_maxima.py

 import pytest
+from pytools.test import mark_test
 
 def test_kernel():
     pytest.importorskip("pexpect")
@@ -63,7 +64,7 @@ def test_lax_round_trip(knl):
     from pymbolic.maxima import MaximaParser
     k_setup = [
             "k:1/(sqrt((x0-(a+t*b))^2+(y0-(c+t*d))^2))",
-            "result:sum(diff(k, t,deg)*t^deg,deg,0,6)",
+            "result:sum(diff(k, t,deg)*t^deg,deg,0,4)",
             ]
     parsed = MaximaParser()(
             knl.clean_eval_str_with_setup(k_setup, "result"))
@@ -79,6 +80,7 @@ def test_diff():
     from pymbolic import parse
     diff(parse("sqrt(x**2+y**2)"), parse("x"))
 
+@mark_test.xfail
 def test_long_command(knl):
     from pymbolic.maxima import set_debug
     set_debug(4)