close() should never be called on an installed LogCapture()

testfixtures/logcapture.py

@@ -298,6 +298,15 @@ def __exit__(self, type, value, traceback):
         self.uninstall()
         self.ensure_checked()
 
+    def close(self):
+        super().close()
+        if self in self.instances:
+            raise AssertionError(
+                'LogCapture instance closed while still installed, '
+                'loggers captured:\n'
+                '%s' % ('\n'.join((str(i.names) for i in self.instances)))
+            )
+
 
 class LogCaptureForDecorator(LogCapture):
 

testfixtures/tests/test_logcapture.py

@@ -1,12 +1,11 @@
-from logging import getLogger, ERROR, Filter
+from logging import getLogger, ERROR, Filter, shutdown
 from textwrap import dedent
 from unittest import TestCase
 from warnings import catch_warnings
 
-from testfixtures.shouldraise import ShouldAssert
-from testfixtures.mock import Mock
-
 from testfixtures import Replacer, LogCapture, compare, Replace
+from testfixtures.mock import Mock
+from testfixtures.shouldraise import ShouldAssert
 
 root = getLogger()
 one = getLogger('one')
@@ -371,6 +370,18 @@ def test_truthiness_when_empty(self):
         handler = LogCapture(install=False)
         assert handler
         assert bool(handler)
+
+    def test_shutdown_while_installed(self):
+        with LogCapture():
+            with ShouldAssert(
+                    'LogCapture instance closed while still installed, loggers captured:\n'
+                    '(None,)'
+            ):
+                shutdown()
+        # second shutdown should be fine:
+        shutdown()
+
+
 class TestCheckPresent:
 
     def test_order_matters_ok(self):