diff --git a/tests/test-check-code.t b/tests/test-check-code.t
--- a/tests/test-check-code.t
+++ b/tests/test-check-code.t
@@ -15,6 +15,7 @@
   Skipping i18n/polib.py it has no-che?k-code (glob)
   Skipping mercurial/statprof.py it has no-che?k-code (glob)
   Skipping tests/badserverext.py it has no-che?k-code (glob)
+  Skipping tests/test-demandimport.py it has no-che?k-code (glob)
 
 @commands in debugcommands.py should be in alphabetical order.
 
diff --git a/tests/test-demandimport.py b/tests/test-demandimport.py
--- a/tests/test-demandimport.py
+++ b/tests/test-demandimport.py
@@ -1,4 +1,6 @@
-from __future__ import absolute_import
+from __future__ import absolute_import, print_function
+
+# no-check-code due to long lines
 
 from mercurial import demandimport
 demandimport.enable()
@@ -6,6 +8,10 @@
 import os
 import subprocess
 import sys
+import types
+
+# Don't import pycompat because it has too many side-effects.
+ispy3 = sys.version_info[0] >= 3
 
 # Only run if demandimport is allowed
 if subprocess.call(['python', '%s/hghave' % os.environ['TESTDIR'],
@@ -16,6 +22,16 @@
 if sys.flags.optimize:
     sys.exit(80)
 
+if ispy3:
+    from importlib.util import _LazyModule
+
+    try:
+        from importlib.util import _Module as moduletype
+    except ImportError:
+        moduletype = types.ModuleType
+else:
+    moduletype = types.ModuleType
+
 if os.name != 'nt':
     try:
         import distutils.msvc9compiler
@@ -43,15 +59,26 @@
 
 # We use assert instead of a unittest test case because having imports inside
 # functions changes behavior of the demand importer.
-assert f(node) == "<module 'mercurial.node' from '?'>", f(node)
+if ispy3:
+    assert not isinstance(node, _LazyModule)
+else:
+    assert f(node) == "<module 'mercurial.node' from '?'>", f(node)
 
 # now enable it for real
 del os.environ['HGDEMANDIMPORT']
 demandimport.enable()
 
 # Test access to special attributes through demandmod proxy
+assert 'mercurial.error' not in sys.modules
 from mercurial import error as errorproxy
-assert f(errorproxy) == "<unloaded module 'error'>", f(errorproxy)
+
+if ispy3:
+    # unsure why this isn't lazy.
+    assert not isinstance(f, _LazyModule)
+    assert f(errorproxy) == "<module 'mercurial.error' from '?'>", f(errorproxy)
+else:
+    assert f(errorproxy) == "<unloaded module 'error'>", f(errorproxy)
+
 doc = ' '.join(errorproxy.__doc__.split()[:3])
 assert doc == 'Mercurial exceptions. This', doc
 assert errorproxy.__name__ == 'mercurial.error', errorproxy.__name__
@@ -61,54 +88,116 @@
 name = errorproxy.__dict__['__name__']
 assert name == 'mercurial.error', name
 
-assert f(errorproxy) == "<proxied module 'error'>", f(errorproxy)
+if ispy3:
+    assert not isinstance(errorproxy, _LazyModule)
+    assert f(errorproxy) == "<module 'mercurial.error' from '?'>", f(errorproxy)
+else:
+    assert f(errorproxy) == "<proxied module 'error'>", f(errorproxy)
 
 import os
 
-assert f(os) == "<unloaded module 'os'>", f(os)
+if ispy3:
+    assert not isinstance(os, _LazyModule)
+    assert f(os) == "<module 'os' from '?'>", f(os)
+else:
+    assert f(os) == "<unloaded module 'os'>", f(os)
+
 assert f(os.system) == '<built-in function system>', f(os.system)
 assert f(os) == "<module 'os' from '?'>", f(os)
 
+assert 'mercurial.utils.procutil' not in sys.modules
 from mercurial.utils import procutil
 
-assert f(procutil) == "<unloaded module 'procutil'>", f(procutil)
+if ispy3:
+    assert isinstance(procutil, _LazyModule)
+    assert f(procutil) == "<module 'mercurial.utils.procutil' from '?'>", f(procutil)
+else:
+    assert f(procutil) == "<unloaded module 'procutil'>", f(procutil)
+
 assert f(procutil.system) == '<function system at 0x?>', f(procutil.system)
+assert procutil.__class__ == moduletype, procutil.__class__
 assert f(procutil) == "<module 'mercurial.utils.procutil' from '?'>", f(procutil)
 assert f(procutil.system) == '<function system at 0x?>', f(procutil.system)
 
+assert 'mercurial.hgweb' not in sys.modules
 from mercurial import hgweb
-assert f(hgweb) == "<unloaded module 'hgweb'>", f(hgweb)
-assert f(hgweb.hgweb_mod) == "<unloaded module 'hgweb_mod'>", f(hgweb.hgweb_mod)
+
+if ispy3:
+    assert not isinstance(hgweb, _LazyModule)
+    assert f(hgweb) == "<module 'mercurial.hgweb' from '?'>", f(hgweb)
+    assert isinstance(hgweb.hgweb_mod, _LazyModule)
+    assert f(hgweb.hgweb_mod) == "<module 'mercurial.hgweb.hgweb_mod' from '?'>", f(hgweb.hgweb_mod)
+else:
+    assert f(hgweb) == "<unloaded module 'hgweb'>", f(hgweb)
+    assert f(hgweb.hgweb_mod) == "<unloaded module 'hgweb_mod'>", f(hgweb.hgweb_mod)
+
 assert f(hgweb) == "<module 'mercurial.hgweb' from '?'>", f(hgweb)
 
 import re as fred
-assert f(fred) == "<unloaded module 're'>", f(fred)
+
+if ispy3:
+    assert not isinstance(fred, _LazyModule)
+    assert f(fred) == "<module 're' from '?'>"
+else:
+    assert f(fred) == "<unloaded module 're'>", f(fred)
 
 import re as remod
-assert f(remod) == "<unloaded module 're'>", f(remod)
+
+if ispy3:
+    assert not isinstance(remod, _LazyModule)
+    assert f(remod) == "<module 're' from '?'>"
+else:
+    assert f(remod) == "<unloaded module 're'>", f(remod)
 
 import sys as re
-assert f(re) == "<unloaded module 'sys'>", f(re)
+
+if ispy3:
+    assert not isinstance(re, _LazyModule)
+    assert f(re) == "<module 'sys' (built-in)>"
+else:
+    assert f(re) == "<unloaded module 'sys'>", f(re)
 
-assert f(fred) == "<unloaded module 're'>", f(fred)
+if ispy3:
+    assert not isinstance(fred, _LazyModule)
+    assert f(fred) == "<module 're' from '?'>", f(fred)
+else:
+    assert f(fred) == "<unloaded module 're'>", f(fred)
+
 assert f(fred.sub) == '<function sub at 0x?>', f(fred.sub)
-assert f(fred) == "<proxied module 're'>", f(fred)
+
+if ispy3:
+    assert not isinstance(fred, _LazyModule)
+    assert f(fred) == "<module 're' from '?'>", f(fred)
+else:
+    assert f(fred) == "<proxied module 're'>", f(fred)
 
 remod.escape  # use remod
 assert f(remod) == "<module 're' from '?'>", f(remod)
 
-assert f(re) == "<unloaded module 'sys'>", f(re)
-assert f(re.stderr) == "<open file '<whatever>', mode 'w' at 0x?>", f(re.stderr)
-assert f(re) == "<proxied module 'sys'>", f(re)
+if ispy3:
+    assert not isinstance(re, _LazyModule)
+    assert f(re) == "<module 'sys' (built-in)>"
+    assert f(type(re.stderr)) == "<class '_io.TextIOWrapper'>", f(type(re.stderr))
+    assert f(re) == "<module 'sys' (built-in)>"
+else:
+    assert f(re) == "<unloaded module 'sys'>", f(re)
+    assert f(re.stderr) == "<open file '<whatever>', mode 'w' at 0x?>", f(re.stderr)
+    assert f(re) == "<proxied module 'sys'>", f(re)
 
 import contextlib
-assert f(contextlib) == "<unloaded module 'contextlib'>", f(contextlib)
+
+if ispy3:
+    assert not isinstance(contextlib, _LazyModule)
+    assert f(contextlib) == "<module 'contextlib' from '?'>"
+else:
+    assert f(contextlib) == "<unloaded module 'contextlib'>", f(contextlib)
+
 try:
     from contextlib import unknownattr
     assert False, ('no demandmod should be created for attribute of non-package '
           'module:\ncontextlib.unknownattr = %s' % f(unknownattr))
 except ImportError as inst:
-    assert rsub(r"'", '', str(inst)) == 'cannot import name unknownattr'
+    assert rsub(r"'", '', str(inst)).startswith('cannot import name unknownattr')
 
 from mercurial import util