Clean up and test the callers debugging info

2 files changed, 17 insertions, 4 deletions

diff --git a/coverage/debug.py b/coverage/debug.py
index 3d67c611..d173f43f 100644
--- a/coverage/debug.py
+++ b/coverage/debug.py
@@ -49,7 +49,7 @@ class DebugControl(object):
             msg = "pid %5d: %s" % (os.getpid(), msg)
         self.output.write(msg+"\n")
         if callers and self.should('callers'):
-            dump_stack_frames(out=self.output)
+            dump_stack_frames(out=self.output, skip=1)
         self.output.flush()
 
     def write_formatted_info(self, header, info):
@@ -109,10 +109,10 @@ def short_stack(limit=None, skip=0):
     return "\n".join("%30s : %s @%d" % (t[3], t[1], t[2]) for t in stack)
 
 
-def dump_stack_frames(limit=None, out=None):                # pragma: debugging
+def dump_stack_frames(limit=None, out=None, skip=0):
     """Print a summary of the stack to stdout, or some place else."""
     out = out or sys.stdout
-    out.write(short_stack(limit=limit))
+    out.write(short_stack(limit=limit, skip=skip+1))
     out.write("\n")
 
 
@@ -121,7 +121,7 @@ def log(msg, stack=False):                                  # pragma: debugging
     with open("/tmp/covlog.txt", "a") as f:
         f.write("{pid}: {msg}\n".format(pid=os.getpid(), msg=msg))
         if stack:
-            dump_stack_frames(out=f)
+            dump_stack_frames(out=f, skip=1)
 
 
 def enable_aspectlib_maybe():
diff --git a/tests/test_debug.py b/tests/test_debug.py
index 8309395b..e80beecf 100644
--- a/tests/test_debug.py
+++ b/tests/test_debug.py
@@ -103,6 +103,19 @@ class DebugTraceTest(CoverageTest):
         self.assertTrue(lines_matching(out_lines, pid_prefix + "Tracing "))
         self.assertTrue(lines_matching(out_lines, pid_prefix + "Not tracing "))
 
+    def test_debug_trace_callers(self):
+        out_lines = self.f1_debug_output(["trace", "callers"])
+
+        # For every "Tracing" or "Not tracing" message, there should be a stack
+        # trace with a line like "_should_trace : /Users/ned/coverage/control.py @616"
+        trace_messages = lines_matching(out_lines, r"^(T|Not t)racing ")
+        should_trace_pattern = r"\s+_should_trace : .*coverage[/\\]control.py @\d+$"
+        should_trace_frames = lines_matching(out_lines, should_trace_pattern)
+        self.assertEqual(len(trace_messages), len(should_trace_frames))
+
+        # The very last line should be a _should_trace frame.
+        self.assertRegex(out_lines[-1], should_trace_pattern)
+
     def test_debug_config(self):
         out_lines = self.f1_debug_output(["config"])