diff --git a/tests/test-ui-config b/tests/test-ui-config
--- a/tests/test-ui-config
+++ b/tests/test-ui-config
@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 
-from mercurial import ui
+from mercurial import ui, util
 
 testui = ui.ui()
 testui.updateopts(config=[
@@ -11,10 +11,19 @@ testui.updateopts(config=[
     'lists.list2=foo bar baz',
     'lists.list3=alice, bob',
     'lists.list4=foo bar baz alice, bob',
+    'interpolation.value1=hallo',
+    'interpolation.value2=%(value1)s world',
+    'interpolation.value3=%(novalue)s',
+    'interpolation.value4=%(bad)1',
+    'interpolation.value5=%bad2',
 ])
 
 print repr(testui.configitems('values'))
 print repr(testui.configitems('lists'))
+try:
+    print repr(testui.configitems('interpolation'))
+except util.Abort, inst:
+    print inst
 print "---"
 print repr(testui.config('values', 'string'))
 print repr(testui.config('values', 'bool1'))
@@ -45,3 +54,18 @@ print repr(testui.configlist('lists', 'u
 print repr(testui.configlist('lists', 'unknown', ['foo bar']))
 print repr(testui.configlist('lists', 'unknown', ['foo', 'bar']))
 print "---"
+print repr(testui.config('interpolation', 'value1'))
+print repr(testui.config('interpolation', 'value2'))
+try:
+    print repr(testui.config('interpolation', 'value3'))
+except util.Abort, inst:
+    print inst
+try:
+    print repr(testui.config('interpolation', 'value4'))
+except util.Abort, inst:
+    print inst
+try:
+    print repr(testui.config('interpolation', 'value5'))
+except util.Abort, inst:
+    print inst
+print "---"