diff --git a/tests/test-dispatch.t b/tests/test-dispatch.t
--- a/tests/test-dispatch.t
+++ b/tests/test-dispatch.t
@@ -217,3 +217,94 @@
   [1]
 
 #endif
+
+Test various exit codes and methods
+
+  $ cd $TESTTMP
+
+  $ cat >> $TESTTMP/exitmodes.py <<'EOF'
+  > from mercurial import pycompat, registrar, commands
+  > cmdtable = {}
+  > command = registrar.command(cmdtable)
+  > @command(b'exit', [], b'[MODE] [VALUE]', norepo=True)
+  > def exitmodes(ui, mode, value=None):
+  >     if mode == b'returnint':
+  >         return int(value)
+  >     elif mode == b'returnstring':
+  >         # sysstr is to make testing easier, since Python 2 and 3 will
+  >         # format bytes and unicode types differently when printed.
+  >         return pycompat.sysstr(value)
+  >     elif mode == b'returnnone':
+  >         return None
+  >     elif mode == b'returnempty':
+  >         return
+  >     elif mode == b'systemexitint':
+  >         raise SystemExit(int(value))
+  >     elif mode == b'systemexitstring':
+  >         raise SystemExit(pycompat.sysstr(value))
+  >     elif mode == b'systemexitnoarg':
+  >         raise SystemExit()
+  >     elif mode == b'systemexitnone':
+  >         raise SystemExit(None)
+  >     elif mode == b'returndict':
+  >         return {'key1': 'value1'}
+  >     elif mode == b'systemexitdict':
+  >         raise SystemExit({'key1': 'value1'})
+  >     else:
+  >         raise Exception('unknown mode: %s' % mode)
+  > EOF
+
+  $ cat >> $HGRCPATH <<'EOF'
+  > [extensions]
+  > exitmodes = $TESTTMP/exitmodes.py
+  > EOF
+
+  $ hg exit returnint 42
+  [42]
+
+  $ hg exit returnstring 'some message'
+  Traceback (most recent call last):
+    File "*/hg", line *, in <module> (glob)
+      dispatch.run()
+    File "*/mercurial/dispatch.py", line *, in run (glob)
+      sys.exit(status & 255)
+  TypeError: unsupported operand type(s) for &: 'str' and 'int'
+  [1]
+
+  $ hg exit returnnone
+
+  $ hg exit returnempty
+
+  $ hg exit returndict
+  Traceback (most recent call last):
+    File "*/hg", line *, in <module> (glob)
+      dispatch.run()
+    File "*/mercurial/dispatch.py", line *, in run (glob)
+      sys.exit(status & 255)
+  TypeError: unsupported operand type(s) for &: 'dict' and 'int'
+  [1]
+
+  $ hg exit systemexitint 42
+  [42]
+
+  $ hg exit systemexitstring 'failure message'
+  Traceback (most recent call last):
+    File "*/hg", line *, in <module> (glob)
+      dispatch.run()
+    File "*/mercurial/dispatch.py", line *, in run (glob)
+      sys.exit(status & 255)
+  TypeError: unsupported operand type(s) for &: 'str' and 'int'
+  [1]
+
+  $ hg exit systemexitnoarg
+
+  $ hg exit systemexitnone
+
+  $ hg exit systemexitdict
+  Traceback (most recent call last):
+    File "*/hg", line *, in <module> (glob)
+      dispatch.run()
+    File "*/mercurial/dispatch.py", line *, in run (glob)
+      sys.exit(status & 255)
+  TypeError: unsupported operand type(s) for &: 'dict' and 'int'
+  [1]