# HG changeset patch
# User Greg Ward <greg@gerg.ca>
# Date 1388717619 18000
# Node ID 4a92eb1484ba054a67af8669d862ff720f0a5731
# Parent  91cf81a362369f8ffdcd2e8ff3beb862fa497aba
layouts: fix crash when importing hgsubversion itself (issue #402)

Mercurial extensions are a bit weird: they aren't normally in
sys.path, so you can't assume that "import hgsubversion" works.
Luckily, Mercurial sneaks a little treat into sys.modules so that
"import hgext_hgsubversion" does work. In fact, to get things working
*as a Mercurial extension*, all that's needed is that trivial change
to two import lines, in layouts/detect.py and layouts/standard.py.

Unfortunately, hgsubversion is also imported as a Python module, in
its own test suite. In that context, there is no "hgext_" trick --
unless we do it in ourselves, which I've done in TestBase.setUp().
That would work fine ... except that test_util imports from
hgsubversion, which ends up importing hgsubversion.layouts.{detect,standard},
which want the "hgext_" trick to work. But it hasn't been done yet
when we're still importing; it doesn't happen until setUp() runs.

So make those two imports happen late, in the functions that need them.

Incidentally, this is only necessary to support Mercurial <= 2.7.
Mercurial got a bit smarter in 2.8:
  http://selenic.com/repo/hg/rev/621a26eb3a99

diff --git a/hgsubversion/layouts/detect.py b/hgsubversion/layouts/detect.py
--- a/hgsubversion/layouts/detect.py
+++ b/hgsubversion/layouts/detect.py
@@ -10,8 +10,6 @@ import os.path
 
 from mercurial import util as hgutil
 
-from hgsubversion import svnwrap
-
 import __init__ as layouts
 
 def layout_from_subversion(svn, revision=None, ui=None):
@@ -26,6 +24,8 @@ def layout_from_subversion(svn, revision
     passed, if any.
 
     """
+    # import late to avoid trouble when running the test suite
+    from hgext_hgsubversion import svnwrap
 
     try:
         rootlist = svn.list_dir('', revision=revision)
diff --git a/hgsubversion/layouts/standard.py b/hgsubversion/layouts/standard.py
--- a/hgsubversion/layouts/standard.py
+++ b/hgsubversion/layouts/standard.py
@@ -2,7 +2,6 @@ import os.path
 import pickle
 
 import base
-import hgsubversion.util as util
 
 class StandardLayout(base.BaseLayout):
     """The standard trunk, branches, tags layout"""
@@ -57,6 +56,9 @@ class StandardLayout(base.BaseLayout):
         return '%s/%s' % (subdir or '', branchpath)
 
     def taglocations(self, meta_data_dir):
+        # import late to avoid trouble when running the test suite
+        from hgext_hgsubversion import util
+
         if self._tag_locations is None:
 
             tag_locations_file = os.path.join(meta_data_dir, 'tag_locations')
diff --git a/tests/test_util.py b/tests/test_util.py
--- a/tests/test_util.py
+++ b/tests/test_util.py
@@ -434,6 +434,8 @@ class TestBase(unittest.TestCase):
 
     def setUp(self):
         _verify_our_modules()
+        if 'hgsubversion' in sys.modules:
+            sys.modules['hgext_hgsubversion'] = sys.modules['hgsubversion']
 
         # the Python 2.7 default of 640 is obnoxiously low
         self.maxDiff = 4096