diff --git a/tests.py b/tests.py
index dfebcb0..7ad1829 100644
--- a/tests.py
+++ b/tests.py
@@ -18,182 +18,152 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 # THE SOFTWARE.
 
+import doctest
+import gc
+import io
+import os
+import tempfile
 import treelog
 import unittest
-import contextlib
-import tempfile
-import os
-import sys
-import hashlib
-import io
 import warnings
-import gc
-import doctest
 
 from treelog import _path, _state
 from treelog.proto import Level, Data
 
 
-class Log(unittest.TestCase):
+@treelog.withcontext
+def generate_test():
+    'decorated function for unit testing'
 
-    maxDiff = None
+    with treelog.warningfile('test.dat', 'wb') as f:
+        f.write(b'test3')
 
-    @contextlib.contextmanager
-    def assertSilent(self):
-        with capture() as captured:
-            yield
-        self.assertEqual(captured.stdout, '')
 
-    @treelog.withcontext
-    def generate_test(self):
-        with treelog.warningfile('test.dat', 'wb') as f:
-            f.write(b'test3')
+def generate():
+    'generate log events for unit testing'
 
-    def generate(self):
-        treelog.user('my message')
-        with treelog.infofile('test.dat', 'w') as f:
-            f.write('test1')
-        with treelog.context('my context'):
-            with treelog.iter.plain('iter', 'abc') as items:
-                for c in items:
-                    treelog.info(c)
-            with treelog.context('empty'):
-                pass
-            treelog.error('multiple..\n  ..lines')
-            with treelog.userfile('test.dat', 'wb') as f:
-                treelog.info('generating')
-                f.write(b'test2')
-        self.generate_test()
-        with treelog.context('context step={}', 0) as format:
-            treelog.info('foo')
-            format(1)
-            treelog.info('bar')
-        treelog.errordata('same.dat', b'test3')
-        with treelog.debugfile('dbg.jpg', 'wb', type='image/jpg') as f:
-            f.write(b'test4')
-        treelog.debug('dbg')
-        treelog.warning('warn')
+    treelog.user('my message')
+    with treelog.infofile('test.dat', 'w') as f:
+        f.write('test1')
+    with treelog.context('my context'):
+        with treelog.iter.plain('iter', 'abc') as items:
+            for c in items:
+                treelog.info(c)
+        with treelog.context('empty'):
+            pass
+        treelog.error('multiple..\n  ..lines')
+        with treelog.userfile('test.dat', 'wb') as f:
+            treelog.info('generating')
+            f.write(b'test2')
+    generate_test()
+    with treelog.context('context step={}', 0) as format:
+        treelog.info('foo')
+        format(1)
+        treelog.info('bar')
+    treelog.errordata('same.dat', b'test3')
+    with treelog.debugfile('dbg.jpg', 'wb', type='image/jpg') as f:
+        f.write(b'test4')
+    treelog.debug('dbg')
+    treelog.warning('warn')
+
+
+class StdoutLog(unittest.TestCase):
+
+    def test_output(self):
+        f = io.StringIO()
+        with treelog.set(treelog.StdoutLog(f)):
+            generate()
+        self.check_output(f)
+
+    def check_output(self, f):
+        self.assertEqual(f.getvalue(),
+           'my message\n'
+           'test.dat [5 bytes]\n'
+           'my context > iter 1 > a\n'
+           'my context > iter 2 > b\n'
+           'my context > iter 3 > c\n'
+           'my context > multiple..\n'
+           '           >   ..lines\n'
+           'my context > test.dat > generating\n'
+           'my context > test.dat [5 bytes]\n'
+           'generate_test > test.dat [5 bytes]\n'
+           'context step=0 > foo\n'
+           'context step=1 > bar\n'
+           'same.dat [5 bytes]\n'
+           'dbg.jpg [image/jpg; 5 bytes]\n'
+           'dbg\n'
+           'warn\n')
+
+
+class RichOutputLog(unittest.TestCase):
+
+    def test_output(self):
+        f = io.StringIO()
+        with treelog.set(treelog.RichOutputLog(f)):
+            generate()
+        self.check_output(f)
+
+    def check_output(self, f):
+        self.assertEqual(f.getvalue(),
+            '\x1b[1;34mmy message\x1b[0m\n'
+            'test.dat > '
+            '\r\x1b[K'
+            '\x1b[1mtest.dat [5 bytes]\x1b[0m\n'
+            'my context > '
+            'iter 0 '
+            '> \x1b[4D1 > '
+            '\x1b[1ma\x1b[0m\nmy context > iter 1 > '
+            '\x1b[4D2 > '
+            '\x1b[1mb\x1b[0m\nmy context > iter 2 > '
+            '\x1b[4D3 > '
+            '\x1b[1mc\x1b[0m\nmy context > iter 3 > '
+            '\x1b[9D\x1b[K'
+            'empty > '
+            '\x1b[8D\x1b[K'
+            '\x1b[1;31mmultiple..\x1b[0m\n           > \x1b[1;31m  ..lines\x1b[0m\nmy context > test.dat > '
+            '\x1b[1mgenerating\x1b[0m\nmy context > test.dat > '
+            '\x1b[11D\x1b[K'
+            '\x1b[1;34mtest.dat [5 bytes]\x1b[0m\nmy context > '
+            '\r\x1b[Kgenerate_test > test.dat > '
+            '\x1b[11D\x1b[K'
+            '\x1b[1;35mtest.dat [5 bytes]\x1b[0m\ngenerate_test > '
+            '\r\x1b[K'
+            'context step=0 > '
+            '\x1b[1mfoo\x1b[0m\n'
+            'context step=0 > '
+            '\x1b[4D1 > '
+            '\x1b[1mbar\x1b[0m\n'
+            'context step=1 > '
+            '\r\x1b[K'
+            '\x1b[1;31msame.dat [5 bytes]\x1b[0m\n'
+            'dbg.jpg > '
+            '\r\x1b[K'
+            '\x1b[1;30mdbg.jpg [image/jpg; 5 bytes]\x1b[0m\n'
+            '\x1b[1;30mdbg\x1b[0m\n'
+            '\x1b[1;35mwarn\x1b[0m\n')
+
+
+class DataLog(unittest.TestCase):
 
     def test_output(self):
-        with self.assertSilent(), self.output_tester() as log, treelog.set(log):
-            self.generate()
-
-
-class StdoutLog(Log):
-
-    @contextlib.contextmanager
-    def output_tester(self):
-        with capture() as captured:
-            yield treelog.StdoutLog()
-        self.assertEqual(captured.stdout,
-                         'my message\n'
-                         'test.dat [5 bytes]\n'
-                         'my context > iter 1 > a\n'
-                         'my context > iter 2 > b\n'
-                         'my context > iter 3 > c\n'
-                         'my context > multiple..\n'
-                         '  ..lines\n'
-                         'my context > test.dat > generating\n'
-                         'my context > test.dat [5 bytes]\n'
-                         'generate_test > test.dat [5 bytes]\n'
-                         'context step=0 > foo\n'
-                         'context step=1 > bar\n'
-                         'same.dat [5 bytes]\n'
-                         'dbg.jpg [image/jpg; 5 bytes]\n'
-                         'dbg\n'
-                         'warn\n')
-        self.assertEqual(captured.stderr, '')
-
-
-class StderrLog(Log):
-
-    @contextlib.contextmanager
-    def output_tester(self):
-        with capture() as captured:
-            yield treelog.StderrLog()
-        self.assertEqual(captured.stderr,
-                         'my message\n'
-                         'test.dat [5 bytes]\n'
-                         'my context > iter 1 > a\n'
-                         'my context > iter 2 > b\n'
-                         'my context > iter 3 > c\n'
-                         'my context > multiple..\n'
-                         '  ..lines\n'
-                         'my context > test.dat > generating\n'
-                         'my context > test.dat [5 bytes]\n'
-                         'generate_test > test.dat [5 bytes]\n'
-                         'context step=0 > foo\n'
-                         'context step=1 > bar\n'
-                         'same.dat [5 bytes]\n'
-                         'dbg.jpg [image/jpg; 5 bytes]\n'
-                         'dbg\n'
-                         'warn\n')
-        self.assertEqual(captured.stdout, '')
-
-
-class RichOutputLog(Log):
-
-    @contextlib.contextmanager
-    def output_tester(self):
-        with capture() as captured:
-            yield treelog.RichOutputLog()
-        self.assertEqual(captured.stdout,
-                         '\x1b[1;34mmy message\x1b[0m\n'
-                         'test.dat > '
-                         '\r\x1b[K'
-                         '\x1b[1mtest.dat [5 bytes]\x1b[0m\n'
-                         'my context > '
-                         'iter 0 '
-                         '> \x1b[4D1 > '
-                         '\x1b[1ma\x1b[0m\nmy context > iter 1 > '
-                         '\x1b[4D2 > '
-                         '\x1b[1mb\x1b[0m\nmy context > iter 2 > '
-                         '\x1b[4D3 > '
-                         '\x1b[1mc\x1b[0m\nmy context > iter 3 > '
-                         '\x1b[9D\x1b[K'
-                         'empty > '
-                         '\x1b[8D\x1b[K'
-                         '\x1b[1;31mmultiple..\n  ..lines\x1b[0m\nmy context > test.dat > '
-                         '\x1b[1mgenerating\x1b[0m\nmy context > test.dat > '
-                         '\x1b[11D\x1b[K'
-                         '\x1b[1;34mtest.dat [5 bytes]\x1b[0m\nmy context > '
-                         '\r\x1b[Kgenerate_test > test.dat > '
-                         '\x1b[11D\x1b[K'
-                         '\x1b[1;35mtest.dat [5 bytes]\x1b[0m\ngenerate_test > '
-                         '\r\x1b[K'
-                         'context step=0 > '
-                         '\x1b[1mfoo\x1b[0m\n'
-                         'context step=0 > '
-                         '\x1b[4D1 > '
-                         '\x1b[1mbar\x1b[0m\n'
-                         'context step=1 > '
-                         '\r\x1b[K'
-                         '\x1b[1;31msame.dat [5 bytes]\x1b[0m\n'
-                         'dbg.jpg > '
-                         '\r\x1b[K'
-                         '\x1b[1;30mdbg.jpg [image/jpg; 5 bytes]\x1b[0m\n'
-                         '\x1b[1;30mdbg\x1b[0m\n'
-                         '\x1b[1;35mwarn\x1b[0m\n')
-
-
-class DataLog(Log):
-
-    @contextlib.contextmanager
-    def output_tester(self):
         with tempfile.TemporaryDirectory() as tmpdir:
-            yield treelog.DataLog(tmpdir)
-            self.assertEqual(set(os.listdir(tmpdir)), {
-                             'test.dat', 'test-1.dat', 'test-2.dat', 'same.dat', 'dbg.jpg'})
-            with open(os.path.join(tmpdir, 'test.dat'), 'r') as f:
-                self.assertEqual(f.read(), 'test1')
-            with open(os.path.join(tmpdir, 'test-1.dat'), 'rb') as f:
-                self.assertEqual(f.read(), b'test2')
-            with open(os.path.join(tmpdir, 'test-2.dat'), 'rb') as f:
-                self.assertEqual(f.read(), b'test3')
-            with open(os.path.join(tmpdir, 'same.dat'), 'rb') as f:
-                self.assertEqual(f.read(), b'test3')
-            with open(os.path.join(tmpdir, 'dbg.jpg'), 'r') as f:
-                self.assertEqual(f.read(), 'test4')
+            with treelog.set(treelog.DataLog(tmpdir)):
+                generate()
+            self.check_output(tmpdir)
+
+    def check_output(self, tmpdir):
+        self.assertEqual(set(os.listdir(tmpdir)), {
+                         'test.dat', 'test-1.dat', 'test-2.dat', 'same.dat', 'dbg.jpg'})
+        with open(os.path.join(tmpdir, 'test.dat'), 'r') as f:
+            self.assertEqual(f.read(), 'test1')
+        with open(os.path.join(tmpdir, 'test-1.dat'), 'rb') as f:
+            self.assertEqual(f.read(), b'test2')
+        with open(os.path.join(tmpdir, 'test-2.dat'), 'rb') as f:
+            self.assertEqual(f.read(), b'test3')
+        with open(os.path.join(tmpdir, 'same.dat'), 'rb') as f:
+            self.assertEqual(f.read(), b'test3')
+        with open(os.path.join(tmpdir, 'dbg.jpg'), 'r') as f:
+            self.assertEqual(f.read(), 'test4')
 
     @unittest.skipIf(not _path.supports_fd, 'dir_fd not supported on platform')
     def test_move_outdir(self):
@@ -208,69 +178,71 @@ def test_move_outdir(self):
             self.assertEqual(os.listdir(outdira), [])
 
 
-class HtmlLog(Log):
+class HtmlLog(unittest.TestCase):
 
-    @contextlib.contextmanager
-    def output_tester(self):
+    def test_output(self):
         with tempfile.TemporaryDirectory() as tmpdir:
-            tests = ['b444ac06613fc8d63795be9ad0beaf55011936ac.dat', '109f4b3c50d7b0df729d299bc6f8e9ef9066971f.dat',
-                     '3ebfa301dc59196f18593c45e519287a23297589.dat', '1ff2b3704aede04eecb51e50ca698efd50a1379b.jpg']
-            with self.assertSilent(), treelog.HtmlLog(tmpdir, title='test') as htmllog:
-                yield htmllog
-            self.assertEqual(htmllog.filename, 'log.html')
-            self.assertGreater(set(os.listdir(tmpdir)), {'log.html', *tests})
-            with open(os.path.join(tmpdir, 'log.html'), 'r') as f:
-                lines = f.readlines()
-            self.assertIn('<body>\n', lines)
-            self.assertEqual(lines[lines.index('<body>\n'):], [
-                '<body>\n',
-                '<div id="header"><div id="bar"><div id="text"><div id="title">test</div></div></div></div>\n',
-                '<div id="log">\n',
-                '<div class="item" data-loglevel="2">my message</div>\n',
-                '<div class="item" data-loglevel="1"><a href="b444ac06613fc8d63795be9ad0beaf55011936ac.dat" download="test.dat">test.dat</a></div>\n',
-                '<div class="context"><div class="title">my context</div><div class="children">\n',
-                '<div class="context"><div class="title">iter 1</div><div class="children">\n',
-                '<div class="item" data-loglevel="1">a</div>\n',
-                '</div><div class="end"></div></div>\n',
-                '<div class="context"><div class="title">iter 2</div><div class="children">\n',
-                '<div class="item" data-loglevel="1">b</div>\n',
-                '</div><div class="end"></div></div>\n',
-                '<div class="context"><div class="title">iter 3</div><div class="children">\n',
-                '<div class="item" data-loglevel="1">c</div>\n',
-                '</div><div class="end"></div></div>\n',
-                '<div class="item" data-loglevel="4">multiple..\n',
-                '  ..lines</div>\n',
-                '<div class="context"><div class="title">test.dat</div><div class="children">\n',
-                '<div class="item" data-loglevel="1">generating</div>\n',
-                '</div><div class="end"></div></div>\n',
-                '<div class="item" data-loglevel="2"><a href="109f4b3c50d7b0df729d299bc6f8e9ef9066971f.dat" download="test.dat">test.dat</a></div>\n',
-                '</div><div class="end"></div></div>\n',
-                '<div class="context"><div class="title">generate_test</div><div class="children">\n',
-                '<div class="item" data-loglevel="3"><a href="3ebfa301dc59196f18593c45e519287a23297589.dat" download="test.dat">test.dat</a></div>\n',
-                '</div><div class="end"></div></div>\n',
-                '<div class="context"><div class="title">context step=0</div><div '
-                'class="children">\n',
-                '<div class="item" data-loglevel="1">foo</div>\n',
-                '</div><div class="end"></div></div>\n',
-                '<div class="context"><div class="title">context step=1</div><div '
-                'class="children">\n',
-                '<div class="item" data-loglevel="1">bar</div>\n',
-                '</div><div class="end"></div></div>\n',
-                '<div class="item" data-loglevel="4"><a href="3ebfa301dc59196f18593c45e519287a23297589.dat" download="same.dat">same.dat</a></div>\n',
-                '<div class="item" data-loglevel="0"><a href="1ff2b3704aede04eecb51e50ca698efd50a1379b.jpg" download="dbg.jpg">dbg.jpg</a></div>\n',
-                '<div class="item" data-loglevel="0">dbg</div>\n',
-                '<div class="item" data-loglevel="3">warn</div>\n',
-                '</div></body></html>\n'])
-            for i, test in enumerate(tests, 1):
-                with open(os.path.join(tmpdir, test), 'rb') as f:
-                    self.assertEqual(f.read(), b'test%i' % i)
+            with treelog.HtmlLog(tmpdir, title='test') as htmllog, treelog.set(htmllog):
+                generate()
+            self.check_output(tmpdir, htmllog.filename)
+
+    def check_output(self, tmpdir, filename):
+        tests = ['b444ac06613fc8d63795be9ad0beaf55011936ac.dat', '109f4b3c50d7b0df729d299bc6f8e9ef9066971f.dat',
+                 '3ebfa301dc59196f18593c45e519287a23297589.dat', '1ff2b3704aede04eecb51e50ca698efd50a1379b.jpg']
+        self.assertEqual(filename, 'log.html')
+        self.assertGreater(set(os.listdir(tmpdir)), {'log.html', *tests})
+        with open(os.path.join(tmpdir, 'log.html'), 'r') as f:
+            lines = f.readlines()
+        self.assertIn('<body>\n', lines)
+        self.assertEqual(lines[lines.index('<body>\n'):], [
+            '<body>\n',
+            '<div id="header"><div id="bar"><div id="text"><div id="title">test</div></div></div></div>\n',
+            '<div id="log">\n',
+            '<div class="item" data-loglevel="2">my message</div>\n',
+            '<div class="item" data-loglevel="1"><a href="b444ac06613fc8d63795be9ad0beaf55011936ac.dat" download="test.dat">test.dat</a></div>\n',
+            '<div class="context"><div class="title">my context</div><div class="children">\n',
+            '<div class="context"><div class="title">iter 1</div><div class="children">\n',
+            '<div class="item" data-loglevel="1">a</div>\n',
+            '</div><div class="end"></div></div>\n',
+            '<div class="context"><div class="title">iter 2</div><div class="children">\n',
+            '<div class="item" data-loglevel="1">b</div>\n',
+            '</div><div class="end"></div></div>\n',
+            '<div class="context"><div class="title">iter 3</div><div class="children">\n',
+            '<div class="item" data-loglevel="1">c</div>\n',
+            '</div><div class="end"></div></div>\n',
+            '<div class="item" data-loglevel="4">multiple..\n',
+            '  ..lines</div>\n',
+            '<div class="context"><div class="title">test.dat</div><div class="children">\n',
+            '<div class="item" data-loglevel="1">generating</div>\n',
+            '</div><div class="end"></div></div>\n',
+            '<div class="item" data-loglevel="2"><a href="109f4b3c50d7b0df729d299bc6f8e9ef9066971f.dat" download="test.dat">test.dat</a></div>\n',
+            '</div><div class="end"></div></div>\n',
+            '<div class="context"><div class="title">generate_test</div><div class="children">\n',
+            '<div class="item" data-loglevel="3"><a href="3ebfa301dc59196f18593c45e519287a23297589.dat" download="test.dat">test.dat</a></div>\n',
+            '</div><div class="end"></div></div>\n',
+            '<div class="context"><div class="title">context step=0</div><div '
+            'class="children">\n',
+            '<div class="item" data-loglevel="1">foo</div>\n',
+            '</div><div class="end"></div></div>\n',
+            '<div class="context"><div class="title">context step=1</div><div '
+            'class="children">\n',
+            '<div class="item" data-loglevel="1">bar</div>\n',
+            '</div><div class="end"></div></div>\n',
+            '<div class="item" data-loglevel="4"><a href="3ebfa301dc59196f18593c45e519287a23297589.dat" download="same.dat">same.dat</a></div>\n',
+            '<div class="item" data-loglevel="0"><a href="1ff2b3704aede04eecb51e50ca698efd50a1379b.jpg" download="dbg.jpg">dbg.jpg</a></div>\n',
+            '<div class="item" data-loglevel="0">dbg</div>\n',
+            '<div class="item" data-loglevel="3">warn</div>\n',
+            '</div></body></html>\n'])
+        for i, test in enumerate(tests, 1):
+            with open(os.path.join(tmpdir, test), 'rb') as f:
+                self.assertEqual(f.read(), b'test%i' % i)
 
     @unittest.skipIf(not _path.supports_fd, 'dir_fd not supported on platform')
     def test_move_outdir(self):
         with tempfile.TemporaryDirectory() as tmpdir:
             outdira = os.path.join(tmpdir, 'a')
             outdirb = os.path.join(tmpdir, 'b')
-            with silent(), treelog.HtmlLog(outdira) as log:
+            with treelog.HtmlLog(outdira) as log:
                 os.rename(outdira, outdirb)
                 os.mkdir(outdira)
                 log.write(Data('dat', b''), Level.info)
@@ -279,24 +251,45 @@ def test_move_outdir(self):
 
     def test_filename_sequence(self):
         with tempfile.TemporaryDirectory() as tmpdir:
-            with silent(), treelog.HtmlLog(tmpdir) as log:
+            with treelog.HtmlLog(tmpdir) as log:
                 pass
             self.assertTrue(os.path.exists(os.path.join(tmpdir, 'log.html')))
-            with silent(), treelog.HtmlLog(tmpdir) as log:
+            with treelog.HtmlLog(tmpdir) as log:
                 pass
             self.assertTrue(os.path.exists(os.path.join(tmpdir, 'log-1.html')))
-            with silent(), treelog.HtmlLog(tmpdir) as log:
+            with treelog.HtmlLog(tmpdir) as log:
                 pass
             self.assertTrue(os.path.exists(os.path.join(tmpdir, 'log-2.html')))
 
 
-class RecordLog(Log):
+class RecordLog(unittest.TestCase):
 
-    @contextlib.contextmanager
-    def output_tester(self):
-        recordlog = treelog.RecordLog(simplify=False)
-        yield recordlog
-        self.assertEqual(recordlog._messages, [
+    simplify = False
+
+    def test_output(self):
+        recordlog = treelog.RecordLog(simplify=self.simplify)
+        with treelog.set(recordlog):
+            generate()
+        self.check_output(recordlog._messages)
+        with self.subTest('replay to StdoutLog'):
+            f = io.StringIO()
+            recordlog.replay(treelog.StdoutLog(f))
+            StdoutLog.check_output(self, f)
+        with self.subTest('replay to DataLog'), tempfile.TemporaryDirectory() as tmpdir:
+            recordlog.replay(treelog.DataLog(tmpdir))
+            DataLog.check_output(self, tmpdir)
+        with self.subTest('replay to HtmlLog'), tempfile.TemporaryDirectory() as tmpdir:
+            with treelog.HtmlLog(tmpdir, title='test') as htmllog:
+                recordlog.replay(htmllog)
+            HtmlLog.check_output(self, tmpdir, htmllog.filename)
+        if not self.simplify:
+            with self.subTest('replay to RichOutputLog'):
+                f = io.StringIO()
+                recordlog.replay(treelog.RichOutputLog(f))
+                RichOutputLog.check_output(self, f)
+
+    def check_output(self, messages):
+        self.assertEqual(messages, [
             ('write', 'my message', Level.user),
             ('pushcontext', 'test.dat'),
             ('popcontext',),
@@ -334,24 +327,20 @@ def output_tester(self):
             ('write', Data('dbg.jpg', b'test4', type='image/jpg'), Level.debug),
             ('write', 'dbg', Level.debug),
             ('write', 'warn', Level.warning)])
-        for Log in StdoutLog, DataLog, HtmlLog, RichOutputLog:
-            with self.subTest('replay to {}'.format(Log.__name__)), Log.output_tester(self) as log:
-                recordlog.replay(log)
 
     def test_replay_in_current(self):
-        recordlog = treelog.RecordLog()
+        recordlog = treelog.RecordLog(simplify=self.simplify)
         recordlog.write('test', level=Level.info)
-        with self.assertSilent(), treelog.set(treelog.LoggingLog()), self.assertLogs('nutils'):
+        with treelog.set(treelog.LoggingLog()), self.assertLogs('nutils'):
             recordlog.replay()
 
 
-class SimplifiedRecordLog(Log):
+class SimplifiedRecordLog(RecordLog):
 
-    @contextlib.contextmanager
-    def output_tester(self):
-        recordlog = treelog.RecordLog(simplify=True)
-        yield recordlog
-        self.assertEqual(recordlog._messages, [
+    simplify = True
+
+    def check_output(self, messages):
+        self.assertEqual(messages, [
             ('write', 'my message', Level.user),
             ('write', Data('test.dat', b'test1'), Level.info),
             ('pushcontext', 'my context'),
@@ -378,54 +367,24 @@ def output_tester(self):
             ('write', Data('dbg.jpg', b'test4', type='image/jpg'), Level.debug),
             ('write', 'dbg', Level.debug),
             ('write', 'warn', Level.warning)])
-        for Log in StdoutLog, DataLog, HtmlLog:
-            with self.subTest('replay to {}'.format(Log.__name__)), Log.output_tester(self) as log:
-                recordlog.replay(log)
-
-    def test_replay_in_current(self):
-        recordlog = treelog.RecordLog()
-        recordlog.write('test', level=Level.info)
-        with self.assertSilent(), treelog.set(treelog.LoggingLog()), self.assertLogs('nutils'):
-            recordlog.replay()
 
 
-class TeeLogTestLog:
+class TeeLog(unittest.TestCase):
 
-    def __init__(self, dir, update, filenos):
-        self._dir = dir
-        self._update = update
-        self.filenos = filenos
-
-    def pushcontext(self, title):
-        pass
-
-    def popcontext(self):
-        pass
-
-    def recontext(self, title):
-        pass
-
-    def write(self, text, level):
-        pass
-
-    @contextlib.contextmanager
-    def open(self, filename, mode, level):
-        with open(os.path.join(self._dir, filename), mode+'+' if self._update else mode) as f:
-            self.filenos.add(f.fileno())
-            try:
-                yield f
-            finally:
-                self.filenos.remove(f.fileno())
-
-
-class TeeLog(Log):
-
-    @contextlib.contextmanager
-    def output_tester(self):
-        with DataLog.output_tester(self) as datalog, \
-                RecordLog.output_tester(self) as recordlog, \
-                RichOutputLog.output_tester(self) as richoutputlog:
-            yield treelog.TeeLog(richoutputlog, treelog.TeeLog(datalog, recordlog))
+    def test_output(self):
+        f = io.StringIO()
+        with tempfile.TemporaryDirectory() as tmpdir:
+            datalog = treelog.DataLog(tmpdir)
+            recordlog = treelog.RecordLog(simplify=False)
+            richoutputlog = treelog.RichOutputLog(f)
+            with treelog.set(treelog.TeeLog(richoutputlog, treelog.TeeLog(datalog, recordlog))):
+                generate()
+            with self.subTest('DataLog'):
+                DataLog.check_output(self, tmpdir)
+            with self.subTest('RecordLog'):
+                RecordLog.check_output(self, recordlog._messages)
+            with self.subTest('RichOutputLog'):
+                RichOutputLog.check_output(self, f)
 
     def test_open_datalog_datalog_samedir(self):
         with tempfile.TemporaryDirectory() as tmpdir:
@@ -438,13 +397,16 @@ def test_open_datalog_datalog_samedir(self):
                 self.assertEqual(f.read(), b'test')
 
 
-class FilterMinLog(Log):
+class FilterMinLog(unittest.TestCase):
 
-    @contextlib.contextmanager
-    def output_tester(self):
+    def test_output(self):
         recordlog = treelog.RecordLog()
-        yield treelog.FilterLog(recordlog, minlevel=Level.user)
-        self.assertEqual(recordlog._messages, [
+        with treelog.set(treelog.FilterLog(recordlog, minlevel=Level.user)):
+            generate()
+        self.check_output(recordlog._messages)
+
+    def check_output(self, messages):
+        self.assertEqual(messages, [
             ('write', 'my message', Level.user),
             ('pushcontext', 'my context'),
             ('write', 'multiple..\n  ..lines', Level.error),
@@ -456,13 +418,16 @@ def output_tester(self):
             ('write', 'warn', Level.warning)])
 
 
-class FilterMaxLog(Log):
+class FilterMaxLog(unittest.TestCase):
 
-    @contextlib.contextmanager
-    def output_tester(self):
+    def test_output(self):
         recordlog = treelog.RecordLog()
-        yield treelog.FilterLog(recordlog, maxlevel=Level.user)
-        self.assertEqual(recordlog._messages, [
+        with treelog.set(treelog.FilterLog(recordlog, maxlevel=Level.user)):
+            generate()
+        self.check_output(recordlog._messages)
+
+    def check_output(self, messages):
+        self.assertEqual(messages, [
             ('write', 'my message', Level.user),
             ('write', Data('test.dat', b'test1'), Level.info),
             ('pushcontext', 'my context'),
@@ -485,13 +450,16 @@ def output_tester(self):
             ('write', 'dbg', Level.debug)])
 
 
-class FilterMinMaxLog(Log):
+class FilterMinMaxLog(unittest.TestCase):
 
-    @contextlib.contextmanager
-    def output_tester(self):
+    def test_output(self):
         recordlog = treelog.RecordLog()
-        yield treelog.FilterLog(recordlog, minlevel=Level.info, maxlevel=Level.warning)
-        self.assertEqual(recordlog._messages, [
+        with treelog.set(treelog.FilterLog(recordlog, minlevel=Level.info, maxlevel=Level.warning)):
+            generate()
+        self.check_output(recordlog._messages)
+
+    def check_output(self, messages):
+        self.assertEqual(messages, [
             ('write', 'my message', Level.user),
             ('write', Data('test.dat', b'test1'), Level.info),
             ('pushcontext', 'my context'),
@@ -515,13 +483,15 @@ def output_tester(self):
             ('write', 'warn', Level.warning)])
 
 
-class LoggingLog(Log):
+class LoggingLog(unittest.TestCase):
 
-    @contextlib.contextmanager
-    def output_tester(self):
-        with self.assertLogs('nutils') as cm:
-            yield treelog.LoggingLog()
-        self.assertEqual(cm.output, [
+    def test_output(self):
+        with self.assertLogs('nutils') as cm, treelog.set(treelog.LoggingLog()):
+            generate()
+        self.check_output(cm.output)
+
+    def check_output(self, output):
+        self.assertEqual(output, [
             'Level 25:nutils:my message',
             'INFO:nutils:test.dat [5 bytes]',
             'INFO:nutils:my context > iter 1 > a',
@@ -537,12 +507,11 @@ def output_tester(self):
             'WARNING:nutils:warn'])
 
 
-class NullLog(Log):
+class NullLog(unittest.TestCase):
 
-    @contextlib.contextmanager
-    def output_tester(self):
-        with self.assertSilent():
-            yield treelog.NullLog()
+    def test_output(self):
+        with treelog.set(treelog.NullLog()):
+            generate()
 
     def test_disable(self):
         with treelog.disable():
@@ -684,27 +653,4 @@ def test_docs(self):
         doctest.testmod(treelog)
 
 
-del Log  # hide from unittest discovery
-
-# INTERNALS
-
-
-@contextlib.contextmanager
-def capture():
-    with tempfile.TemporaryFile('w+', newline='') as stdout, tempfile.TemporaryFile('w+', newline='') as stderr:
-        class captured:
-            pass
-        with contextlib.redirect_stdout(stdout), contextlib.redirect_stderr(stderr):
-            yield captured
-        stdout.seek(0)
-        captured.stdout = stdout.read()
-        stderr.seek(0)
-        captured.stderr = stderr.read()
-
-
-@contextlib.contextmanager
-def silent():
-    with open(os.devnull, 'w') as f, contextlib.redirect_stdout(f):
-        yield
-
-# vim:sw=2:sts=2:et
+# vim:sw=4:sts=4:et
diff --git a/treelog/__init__.py b/treelog/__init__.py
index 46130c5..21b5836 100644
--- a/treelog/__init__.py
+++ b/treelog/__init__.py
@@ -28,14 +28,9 @@
     'NullLog',
     'RecordLog',
     'RichOutputLog',
-    'StderrLog',
     'StdoutLog',
     'TeeLog',
 }
-_legacy = {
-    'version': __version__,
-    'Log': None,
-}
 
 def __dir__():
     return (
@@ -44,7 +39,6 @@ def __dir__():
         *_state_attrs,
         *_state_funcs,
         *_log_objs,
-        *_legacy,
     )
 
 def __getattr__(attr):
@@ -59,8 +53,6 @@ def __getattr__(attr):
         obj = getattr(m, attr)
     elif attr in _sub_mods:
         obj = import_module(f'.{attr}', 'treelog')
-    elif attr in _legacy:
-        obj = _legacy[attr]
     else:
         raise AttributeError(attr)
     globals()[attr] = obj
diff --git a/treelog/_context.py b/treelog/_context.py
deleted file mode 100644
index 8e51013..0000000
--- a/treelog/_context.py
+++ /dev/null
@@ -1,28 +0,0 @@
-class ContextLog:
-    '''Base class for loggers that keep track of the current list of contexts.
-
-    The base class implements :meth:`context` and :meth:`open` which keep the
-    attribute :attr:`currentcontext` up-to-date.
-
-    .. attribute:: currentcontext
-
-       A :class:`list` of contexts (:class:`str`\\s) that are currently active.
-    '''
-
-    def __init__(self) -> None:
-        self.currentcontext = []  # type: typing.List[str]
-
-    def pushcontext(self, title: str) -> None:
-        self.currentcontext.append(title)
-        self.contextchangedhook()
-
-    def popcontext(self) -> None:
-        self.currentcontext.pop()
-        self.contextchangedhook()
-
-    def recontext(self, title: str) -> None:
-        self.currentcontext[-1] = title
-        self.contextchangedhook()
-
-    def contextchangedhook(self) -> None:
-        pass
diff --git a/treelog/_data.py b/treelog/_data.py
index e8c04ff..e51e685 100644
--- a/treelog/_data.py
+++ b/treelog/_data.py
@@ -2,7 +2,7 @@
 import os
 import typing
 
-from ._path import makedirs, sequence
+from ._path import makedirs, sequence, non_existent
 from .proto import Level, Data
 
 
@@ -24,13 +24,6 @@ def recontext(self, title: str) -> None:
 
     def write(self, msg, level: Level) -> None:
         if isinstance(msg, Data):
-            for filename in self._names(msg.name):
-                try:
-                    f = (self._path / filename).open('xb')
-                except FileExistsError:
-                    continue
-                break
-            else:
-                raise ValueError('all filenames are in use')
+            _, f = non_existent(self._path, self._names(msg.name), lambda p: p.open('xb'))
             with f:
                 f.write(msg.data)
diff --git a/treelog/_html.py b/treelog/_html.py
index c714f90..467091b 100644
--- a/treelog/_html.py
+++ b/treelog/_html.py
@@ -8,7 +8,7 @@
 import urllib.parse
 import warnings
 
-from ._path import makedirs, sequence
+from ._path import makedirs, sequence, non_existent
 from .proto import Level, Data
 
 
@@ -17,14 +17,7 @@ class HtmlLog:
 
     def __init__(self, dirpath: str, *, filename: str = 'log.html', title: typing.Optional[str] = None, htmltitle: typing.Optional[str] = None, favicon: typing.Optional[str] = None) -> None:
         self._path = makedirs(dirpath)
-        for self.filename in sequence(filename):
-            try:
-                self._file = (self._path / self.filename).open('x', encoding='utf-8')
-            except FileExistsError:
-                continue
-            break
-        else:
-            raise ValueError('all filenames are in use')
+        self.filename, self._file = non_existent(self._path, sequence(filename), lambda p: p.open('x', encoding='utf-8'))
         css = self._write_hash(CSS.encode(), '.css')
         js = self._write_hash(JS.encode(), '.js')
         if title is None:
diff --git a/treelog/_logging.py b/treelog/_logging.py
index 7b3b514..93f6d0f 100644
--- a/treelog/_logging.py
+++ b/treelog/_logging.py
@@ -1,11 +1,10 @@
 import logging
 import typing
 
-from ._context import ContextLog
 from .proto import Level
 
 
-class LoggingLog(ContextLog):
+class LoggingLog:
     '''Log to Python's built-in logging facility.'''
 
     # type: typing.ClassVar[typing.Tuple[int, int, int, int, int]]
@@ -13,7 +12,16 @@ class LoggingLog(ContextLog):
 
     def __init__(self, name: str = 'nutils') -> None:
         self._logger = logging.getLogger(name)
-        super().__init__()
+        self.currentcontext = []  # type: typing.List[str]
+
+    def pushcontext(self, title: str) -> None:
+        self.currentcontext.append(title)
+
+    def popcontext(self) -> None:
+        self.currentcontext.pop()
+
+    def recontext(self, title: str) -> None:
+        self.currentcontext[-1] = title
 
     def write(self, msg, level: Level, data: typing.Optional[bytes] = None) -> None:
         self._logger.log(self._levels[level.value], ' > '.join(
diff --git a/treelog/_path.py b/treelog/_path.py
index 0885f76..ee8398c 100644
--- a/treelog/_path.py
+++ b/treelog/_path.py
@@ -27,6 +27,23 @@ def sequence(filename: str) -> typing.Generator[str, None, None]:
         i += 1
 
 
+def non_existent(path, names, f):
+    if isinstance(path, str):
+        path = pathlib.Path(path)
+    for name in names:
+        try:
+            return name, f(path / name)
+        except FileExistsError:
+            pass
+        except PermissionError:
+            # On Windows, trying to open a path that exists as a directory
+            # triggers a permission error. To avoid a runaway iteration, we
+            # continue to the next name only if the path indeed exists.
+            if not isinstance(path, pathlib.Path) or not (path / name).exists():
+                raise
+    raise Exception('names exhausted')
+
+
 class _FDDirPath:
 
     def __init__(self, dir_fd: int) -> None:
diff --git a/treelog/_record.py b/treelog/_record.py
index b647034..399ce21 100644
--- a/treelog/_record.py
+++ b/treelog/_record.py
@@ -61,7 +61,6 @@ def replay(self, log: typing.Optional[Log] = None) -> None:
         All recorded messages and files will be written to the log that is either
         directly specified or currently active.'''
 
-        files = {}
         if log is None:
             from ._state import current as log
         for cmd, *args in self._messages:
diff --git a/treelog/_richoutput.py b/treelog/_richoutput.py
index bcd6b3e..a0fd774 100644
--- a/treelog/_richoutput.py
+++ b/treelog/_richoutput.py
@@ -1,11 +1,10 @@
 import sys
 import typing
 
-from ._context import ContextLog
 from .proto import Level
 
 
-class RichOutputLog(ContextLog):
+class RichOutputLog:
     '''Output rich (colored,unicode) text to stream.'''
 
     _cmap = (
@@ -15,10 +14,23 @@ class RichOutputLog(ContextLog):
         '\033[1;35m',  # warning: bold purple
         '\033[1;31m')  # error: bold red
 
-    def __init__(self) -> None:
-        super().__init__()
+    def __init__(self, file=sys.stdout) -> None:
         self._current = ''  # currently printed context
+        self.file = file
         set_ansi_console()
+        self.currentcontext = []  # type: typing.List[str]
+
+    def pushcontext(self, title: str) -> None:
+        self.currentcontext.append(title)
+        self.contextchangedhook()
+
+    def popcontext(self) -> None:
+        self.currentcontext.pop()
+        self.contextchangedhook()
+
+    def recontext(self, title: str) -> None:
+        self.currentcontext[-1] = title
+        self.contextchangedhook()
 
     def contextchangedhook(self) -> None:
         _current = ''.join(item + ' > ' for item in self.currentcontext)
@@ -34,13 +46,16 @@ def contextchangedhook(self) -> None:
             items.append(_current[n:])
         if len(_current) < len(self._current):
             items.append('\033[K')
-        sys.stdout.write(''.join(items))
-        sys.stdout.flush()
+        self.file.write(''.join(items))
+        self.file.flush()
         self._current = _current
 
     def write(self, msg, level: Level) -> None:
-        sys.stdout.write(
-            ''.join([self._cmap[level.value], str(msg), '\033[0m\n', self._current]))
+        msg = str(msg)
+        if self._current and '\n' in msg:
+            msg = msg.replace('\n', '\033[0m\n' + ' > '.rjust(len(self._current)) + self._cmap[level.value])
+        self.file.write(
+            ''.join([self._cmap[level.value], msg, '\033[0m\n', self._current]))
 
 
 def first(items: typing.Iterable[bool]) -> int:
diff --git a/treelog/_stderr.py b/treelog/_stderr.py
deleted file mode 100644
index 4953355..0000000
--- a/treelog/_stderr.py
+++ /dev/null
@@ -1,11 +0,0 @@
-import sys
-
-from ._context import ContextLog
-from .proto import Level
-
-
-class StderrLog(ContextLog):
-    '''Output plain text to stream.'''
-
-    def write(self, msg, level: Level) -> None:
-        print(*self.currentcontext, msg, sep=' > ', file=sys.stderr)
diff --git a/treelog/_stdout.py b/treelog/_stdout.py
index 815825e..fcc846c 100644
--- a/treelog/_stdout.py
+++ b/treelog/_stdout.py
@@ -1,9 +1,26 @@
+import sys
+
 from . import proto
-from ._context import ContextLog
 
 
-class StdoutLog(ContextLog):
+class StdoutLog:
     '''Output plain text to stream.'''
 
+    def __init__(self, file=sys.stdout):
+        self.file = file
+        self.currentcontext = []  # type: typing.List[str]
+
+    def pushcontext(self, title: str) -> None:
+        self.currentcontext.append(title + ' > ')
+
+    def popcontext(self) -> None:
+        self.currentcontext.pop()
+
+    def recontext(self, title: str) -> None:
+        self.currentcontext[-1] = title + ' > '
+
     def write(self, msg, level: proto.Level) -> None:
-        print(*self.currentcontext, msg, sep=' > ')
+        if self.currentcontext:
+            prefix = ''.join(self.currentcontext)
+            msg = prefix + str(msg).replace('\n', '\n' + ' > '.rjust(len(prefix)))
+        print(msg, file=self.file)