Add 'join' method to TempDir.

3 files changed, 36 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index 7338b62..a994487 100644
--- a/NEWS
+++ b/NEWS
@@ -6,6 +6,11 @@ fixtures release notes
 NEXT
 ~~~~
 
+CHANGES:
+
+* Add ``join`` method to ``TempDir`` to more readily get paths relative
+  to a temporary directory.  (Jonathan Lange)
+
 
 0.3.9
 ~~~~~
diff --git a/lib/fixtures/_fixtures/tempdir.py b/lib/fixtures/_fixtures/tempdir.py
index fd5502c..663d3eb 100644
--- a/lib/fixtures/_fixtures/tempdir.py
+++ b/lib/fixtures/_fixtures/tempdir.py
@@ -18,6 +18,7 @@ __all__ = [
     'TempDir',
     ]
 
+import os
 import shutil
 import tempfile
 
@@ -43,6 +44,15 @@ class TempDir(fixtures.Fixture):
         self.path = tempfile.mkdtemp(dir=self.rootdir)
         self.addCleanup(shutil.rmtree, self.path, ignore_errors=True)
 
+    def join(self, *children):
+        """Return an absolute path, given one relative to this ``TempDir``.
+
+        WARNING: This does not do any checking of ``children`` to make sure
+        they aren't walking up the tree using path segments like '..' or
+        '/usr'.  Use at your own risk.
+        """
+        return os.path.abspath(os.path.join(self.path, *children))
+
 
 class NestedTempfile(fixtures.Fixture):
     """Nest all temporary files and directories inside another directory.
diff --git a/lib/fixtures/tests/_fixtures/test_tempdir.py b/lib/fixtures/tests/_fixtures/test_tempdir.py
index 7fc5d45..d0def55 100644
--- a/lib/fixtures/tests/_fixtures/test_tempdir.py
+++ b/lib/fixtures/tests/_fixtures/test_tempdir.py
@@ -46,6 +46,27 @@ class TestTempDir(testtools.TestCase):
         with fixture:
             self.assertThat(fixture.path, StartsWith(root))
 
+    def test_join(self):
+        temp_dir = self.useFixture(TempDir())
+        root = temp_dir.path
+        relpath = 'foo/bar/baz'
+        self.assertEqual(
+            os.path.join(root, relpath), temp_dir.join(relpath))
+
+    def test_join_multiple_children(self):
+        temp_dir = self.useFixture(TempDir())
+        root = temp_dir.path
+        self.assertEqual(
+            os.path.join(root, 'foo', 'bar', 'baz'),
+            temp_dir.join('foo', 'bar', 'baz'))
+
+    def test_join_naughty_children(self):
+        temp_dir = self.useFixture(TempDir())
+        root = temp_dir.path
+        self.assertEqual(
+            os.path.abspath(os.path.join(root, '..', 'bar', 'baz')),
+            temp_dir.join('..', 'bar', 'baz'))
+
 
 class NestedTempfileTest(testtools.TestCase):
     """Tests for `NestedTempfile`."""