tests: actually check that HGDEMANDIMPORT=disable disables demandimport

At the point in the test where we were checking that the 'node' got
eagerly loaded, it had already been loaded (via the pvec module), so
our check wasn't doing anything (i.e. the test would pass even if you
removed the line that set HGDEMANDIMPORT=disable). Let's move this
test earlier so it tests what it was meant to test.

Differential Revision: https://phab.mercurial-scm.org/D2286

tests/test-demandimport.py

@@ -1,106 +1,109 b''
 from __future__ import absolute_import, print_function
 
 from mercurial import demandimport
 demandimport.enable()
 
 import os
 import subprocess
 import sys
 
 # Only run if demandimport is allowed
 if subprocess.call(['python', '%s/hghave' % os.environ['TESTDIR'],
                     'demandimport']):
     sys.exit(80)
 
 if os.name != 'nt':
     try:
         import distutils.msvc9compiler
         print('distutils.msvc9compiler needs to be an immediate '
               'importerror on non-windows platforms')
         distutils.msvc9compiler
     except ImportError:
         pass
 
 import re
 
 rsub = re.sub
 def f(obj):
     l = repr(obj)
     l = rsub("0x[0-9a-fA-F]+", "0x?", l)
     l = rsub("from '.*'", "from '?'", l)
     l = rsub("'<[a-z]*>'", "'<whatever>'", l)
     return l
 
+demandimport.disable()
+os.environ['HGDEMANDIMPORT'] = 'disable'
+# this enable call should not actually enable demandimport!
+demandimport.enable()
+from mercurial import node
+print("node =", f(node))
+# now enable it for real
+del os.environ['HGDEMANDIMPORT']
+demandimport.enable()
+
 import os
 
 print("os =", f(os))
 print("os.system =", f(os.system))
 print("os =", f(os))
 
 from mercurial import util
 
 print("util =", f(util))
 print("util.system =", f(util.system))
 print("util =", f(util))
 print("util.system =", f(util.system))
 
 from mercurial import hgweb
 print("hgweb =", f(hgweb))
 print("hgweb_mod =", f(hgweb.hgweb_mod))
 print("hgweb =", f(hgweb))
 
 import re as fred
 print("fred =", f(fred))
 
 import re as remod
 print("remod =", f(remod))
 
 import sys as re
 print("re =", f(re))
 
 print("fred =", f(fred))
 print("fred.sub =", f(fred.sub))
 print("fred =", f(fred))
 
 remod.escape  # use remod
 print("remod =", f(remod))
 
 print("re =", f(re))
 print("re.stderr =", f(re.stderr))
 print("re =", f(re))
 
 # Test access to special attributes through demandmod proxy
 from mercurial import pvec as pvecproxy
 print("pvecproxy =", f(pvecproxy))
 print("pvecproxy.__doc__ = %r"
       % (' '.join(pvecproxy.__doc__.split()[:3]) + ' ...'))
 print("pvecproxy.__name__ = %r" % pvecproxy.__name__)
 # __name__ must be accessible via __dict__ so the relative imports can be
 # resolved
 print("pvecproxy.__dict__['__name__'] = %r" % pvecproxy.__dict__['__name__'])
 print("pvecproxy =", f(pvecproxy))
 
 import contextlib
 print("contextlib =", f(contextlib))
 try:
     from contextlib import unknownattr
     print('no demandmod should be created for attribute of non-package '
           'module:\ncontextlib.unknownattr =', f(unknownattr))
 except ImportError as inst:
     print('contextlib.unknownattr = ImportError: %s'
           % rsub(r"'", '', str(inst)))
 
 # Unlike the import statement, __import__() function should not raise
 # ImportError even if fromlist has an unknown item
 # (see Python/import.c:import_module_level() and ensure_fromlist())
 contextlibimp = __import__('contextlib', globals(), locals(), ['unknownattr'])
 print("__import__('contextlib', ..., ['unknownattr']) =", f(contextlibimp))
 print("hasattr(contextlibimp, 'unknownattr') =",
       util.safehasattr(contextlibimp, 'unknownattr'))
-
-demandimport.disable()
-os.environ['HGDEMANDIMPORT'] = 'disable'
-# this enable call should not actually enable demandimport!
-demandimport.enable()
-from mercurial import node
-print("node =", f(node))

tests/test-demandimport.py.out

@@ -1,30 +1,30 b''
+node = <module 'mercurial.node' from '?'>
 os = <unloaded module 'os'>
 os.system = <built-in function system>
 os = <module 'os' from '?'>
 util = <unloaded module 'util'>
 util.system = <function system at 0x?>
 util = <module 'mercurial.util' from '?'>
 util.system = <function system at 0x?>
 hgweb = <unloaded module 'hgweb'>
 hgweb_mod = <unloaded module 'hgweb_mod'>
 hgweb = <module 'mercurial.hgweb' from '?'>
 fred = <unloaded module 're'>
 remod = <unloaded module 're'>
 re = <unloaded module 'sys'>
 fred = <unloaded module 're'>
 fred.sub = <function sub at 0x?>
 fred = <proxied module 're'>
 remod = <module 're' from '?'>
 re = <unloaded module 'sys'>
 re.stderr = <open file '<whatever>', mode 'w' at 0x?>
 re = <proxied module 'sys'>
 pvecproxy = <unloaded module 'pvec'>
 pvecproxy.__doc__ = 'A "pvec" is ...'
 pvecproxy.__name__ = 'mercurial.pvec'
 pvecproxy.__dict__['__name__'] = 'mercurial.pvec'
 pvecproxy = <proxied module 'pvec'>
 contextlib = <unloaded module 'contextlib'>
 contextlib.unknownattr = ImportError: cannot import name unknownattr
 __import__('contextlib', ..., ['unknownattr']) = <module 'contextlib' from '?'>
 hasattr(contextlibimp, 'unknownattr') = False
-node = <module 'mercurial.node' from '?'>