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

6 files changed, 35 insertions, 10 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")
diff --git a/tests/coveragetest.py b/tests/coveragetest.py
index dacb9b63..4a917192 100644
--- a/tests/coveragetest.py
+++ b/tests/coveragetest.py
@@ -397,9 +397,8 @@ class CoverageTest(
 
         # Add our test modules directory to PYTHONPATH.  I'm sure there's too
         # much path munging here, but...
-        here = os.path.dirname(self.nice_file(coverage.__file__, ".."))
-        testmods = self.nice_file(here, 'tests/modules')
-        zipfile = self.nice_file(here, 'tests/zipmods.zip')
+        testmods = self.nice_file(self.here(), 'tests/modules')
+        zipfile = self.nice_file(self.here(), 'tests/zipmods.zip')
         pypath = os.getenv('PYTHONPATH', '')
         if pypath:
             pypath += os.pathsep
@@ -410,6 +409,9 @@ class CoverageTest(
         print(self.last_command_output)
         return self.last_command_status, self.last_command_output
 
+    def here(self):
+        return os.path.dirname(self.nice_file(coverage.__file__, ".."))
+        
     def report_from_command(self, cmd):
         """Return the report from the `cmd`, with some convenience added."""
         report = self.run_command(cmd).replace('\\', '/')
diff --git a/tests/modules/zerocoverage/__init__.py b/tests/modules/zerocoverage/__init__.py
new file mode 100644
index 00000000..0acf595e
--- /dev/null
+++ b/tests/modules/zerocoverage/__init__.py
@@ -0,0 +1 @@
+# no empty file to please hg
diff --git a/tests/modules/zerocoverage/__main__.py b/tests/modules/zerocoverage/__main__.py
new file mode 100644
index 00000000..91082160
--- /dev/null
+++ b/tests/modules/zerocoverage/__main__.py
@@ -0,0 +1 @@
+print('done')
diff --git a/tests/modules/zerocoverage/zero.py b/tests/modules/zerocoverage/zero.py
new file mode 100644
index 00000000..6ae283f1
--- /dev/null
+++ b/tests/modules/zerocoverage/zero.py
@@ -0,0 +1,3 @@
+def method(self):
+    while True:
+        return 1
diff --git a/tests/test_arcs.py b/tests/test_arcs.py
index 2fd033b8..50751826 100644
--- a/tests/test_arcs.py
+++ b/tests/test_arcs.py
@@ -252,10 +252,12 @@ class LoopArcTest(CoverageTest):
             """,
             arcz=".1 12 23 34 45 36 63 57 7.",
             )
-        # With "while True", 2.x thinks it's computation, 3.x thinks it's
-        # constant.
+        # With "while True", 2.x thinks it's computation, 
+        # 2.7+ and 3.x thinks it's constant.
         if env.PY3:
             arcz = ".1 12 23 34 45 36 63 57 7."
+        elif env.PYVERSION >= (2, 7):
+            arcz = ".1 12 23 34 45 36 62 57 7."
         else:
             arcz = ".1 12 23 27 34 45 36 62 57 7."
         self.check_coverage("""\
@@ -270,10 +272,25 @@ class LoopArcTest(CoverageTest):
             arcz=arcz,
         )
 
+    def test_zero_coverage_and_regexps(self):
+        # https://bitbucket.org/ned/coveragepy/issue/502        
+        if env.PYVERSION < (2, 7):
+            self.skipTest("No node.id before 2.7")
+        self.clean_local_file_imports()
+        zerocoverage_path = self.nice_file(self.here(), 'tests/modules/zerocoverage')
+        out = self.run_command(
+            "coverage run --branch --source {0} -m zerocoverage".format(zerocoverage_path))
+        self.assertEqual(out, 'done\n')
+        report = self.report_from_command("coverage report -m")
+        squeezed = self.squeezed_lines(report)
+        self.assertIn("zero.py 3 3 0 0 0% 1-3", squeezed[4])
+
     def test_bug_496_continue_in_constant_while(self):
         # https://bitbucket.org/ned/coveragepy/issue/496
         if env.PY3:
             arcz = ".1 12     23 34 45 53 46 6."
+        elif env.PYVERSION >= (2, 7):
+            arcz = ".1 12     23 34 45 52 46 6."
         else:
             arcz = ".1 12 2-1 23 34 45 52 46 6."
         self.check_coverage("""\