COVERAGE_DEBUG_FILE accepts "stdout" and "stderr"

3 files changed, 8 insertions, 1 deletions

diff --git a/CHANGES.rst b/CHANGES.rst
index 3c65e5d8..1dd5c175 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -33,6 +33,9 @@ Unreleased
   imported a file that will be measured" warnings about Django itself.  These
   have been fixed, closing `issue 1150`_.
 
+- The ``COVERAGE_DEBUG_FILE`` environment variable now accepts ``stdout`` and
+  ``stderr`` to write to those destinations.
+
 .. _Django coverage plugin: https://pypi.org/project/django-coverage-plugin/
 .. _issue 1150: https://github.com/nedbat/coveragepy/issues/1150
 
diff --git a/coverage/debug.py b/coverage/debug.py
index f86e0244..da4093ff 100644
--- a/coverage/debug.py
+++ b/coverage/debug.py
@@ -307,7 +307,9 @@ class DebugOutputFile:                              # pragma: debugging
         if the_one is None or is_interim:
             if fileobj is None:
                 debug_file_name = os.environ.get("COVERAGE_DEBUG_FILE", FORCED_DEBUG_FILE)
-                if debug_file_name:
+                if debug_file_name in ("stdout", "stderr"):
+                    fileobj = getattr(sys, debug_file_name)
+                elif debug_file_name:
                     fileobj = open(debug_file_name, "a")
                 else:
                     fileobj = sys.stderr
diff --git a/doc/cmd.rst b/doc/cmd.rst
index 111d1274..b4bf41ab 100644
--- a/doc/cmd.rst
+++ b/doc/cmd.rst
@@ -594,3 +594,5 @@ a comma-separated list of these options.
 
 The debug output goes to stderr, unless the ``COVERAGE_DEBUG_FILE`` environment
 variable names a different file, which will be appended to.
+``COVERAGE_DEBUG_FILE`` accepts the special names ``stdout`` and ``stderr`` to
+write to those destinations.