"coverage debug premain"

coverage/cmdline.py

@@ -715,7 +715,7 @@ def do_debug(self, args):
         """Implementation of 'coverage debug'."""
 
         if not args:
-            show_help("What information would you like: config, data, sys?")
+            show_help("What information would you like: config, data, sys, premain?")
             return ERR
 
         for info in args:
@@ -747,6 +747,10 @@ def do_debug(self, args):
                 config_info = self.coverage.config.__dict__.items()
                 for line in info_formatter(config_info):
                     print(" %s" % line)
+            elif info == "premain":
+                print(info_header("premain"))
+                from coverage.debug import short_stack
+                print(short_stack())
             else:
                 show_help("Don't know what you mean by %r" % info)
                 return ERR

doc/cmd.rst

@@ -498,8 +498,9 @@ command can often help::
 Three types of information are available:
 
 * ``config``: show coverage's configuration
-* ``sys``: show system configuration,
+* ``sys``: show system configuration
 * ``data``: show a summary of the collected coverage data
+* ``premain``: show the call stack invoking coverage
 
 
 .. _cmd_run_debug:

tests/test_cmdline.py

@@ -248,7 +248,7 @@ def test_combine_doesnt_confuse_options_with_args(self):
             """)
 
     def test_debug(self):
-        self.cmd_help("debug", "What information would you like: config, data, sys?")
+        self.cmd_help("debug", "What information would you like: config, data, sys, premain?")
         self.cmd_help("debug foo", "Don't know what you mean by 'foo'")
 
     def test_debug_sys(self):