also use AST for while constants in python-2.7 #502

The node.id is set to False, True or None is python-2.7: there is no
reason to only check for it with python-3. It is more reliable than
using the DEFAULT_PARTIAL_ALWAYS regexps on source lines.

close #502

--HG--
branch : issue-502-7

1 files changed, 6 insertions, 5 deletions

diff --git a/coverage/parser.py b/coverage/parser.py
index f65e4abb..e2708519 100644
--- a/coverage/parser.py
+++ b/coverage/parser.py
@@ -644,11 +644,12 @@ class AstArcAnalyzer(object):
         """Is this a compile-time constant?"""
         node_name = node.__class__.__name__
         if node_name in ["NameConstant", "Num"]:
-            return True
+            return "Num"
         elif node_name == "Name":
-            if env.PY3 and node.id in ["True", "False", "None"]:
-                return True
-        return False
+            if (( env.PY3 or env.PYVERSION >= (2, 7)) and 
+                node.id in ["True", "False", "None"]):
+                return "Name"
+        return None
 
     # In the fullness of time, these might be good tests to write:
     #   while EXPR:
@@ -950,7 +951,7 @@ class AstArcAnalyzer(object):
     def _handle__While(self, node):
         constant_test = self.is_constant_expr(node.test)
         start = to_top = self.line_for_node(node.test)
-        if constant_test:
+        if constant_test and (env.PY3 or constant_test == "Num"):
             to_top = self.line_for_node(node.body[0])
         self.block_stack.append(LoopBlock(start=to_top))
         from_start = ArcStart(start, cause="the condition on line {lineno} was never true")