diff --git a/openerp/addons/base/tests/__init__.py b/openerp/addons/base/tests/__init__.py
index 42fef2eb39d..409f9928c6f 100644
--- a/openerp/addons/base/tests/__init__.py
+++ b/openerp/addons/base/tests/__init__.py
@@ -1,5 +1,7 @@
-import test_ir_values, test_base
+import test_base, test_expression, test_ir_values
 
 checks = [
-    test_ir_values, test_base
+    test_base,
+    test_expression,
+    test_ir_values,
 ]
diff --git a/openerp/addons/base/tests/test_expression.py b/openerp/addons/base/tests/test_expression.py
new file mode 100644
index 00000000000..0bdd4180c0b
--- /dev/null
+++ b/openerp/addons/base/tests/test_expression.py
@@ -0,0 +1,58 @@
+import unittest2
+
+import openerp.tests.common as common
+
+class test_expression(common.TransactionCase):
+
+    def test_00(self):
+
+        registry, cr, uid = self.registry, self.cr, self.uid
+
+        categories = registry('res.partner.category')
+        cat_a = categories.create(cr, uid, {'name': 'test_expression_category_A'})
+        cat_b = categories.create(cr, uid, {'name': 'test_expression_category_B'})
+
+        partners = registry('res.partner')
+        a = partners.create(cr, uid, {'name': 'test_expression_partner_A', 'category_id': [(6, 0, [cat_a])]})
+        b = partners.create(cr, uid, {'name': 'test_expression_partner_B', 'category_id': [(6, 0, [cat_b])]})
+        ab = partners.create(cr, uid, {'name': 'test_expression_partner_AB', 'category_id': [(6, 0, [cat_a, cat_b])]})
+        c = partners.create(cr, uid, {'name': 'test_expression_partner_C'})
+
+        with_a = partners.search(cr, uid, [('category_id', 'in', [cat_a])])
+        self.assertEqual(set([a, ab]), set(with_a), "Search for category_id in cat_a failed.")
+
+        with_b = partners.search(cr, uid, [('category_id', 'in', [cat_b])])
+        self.assertEqual(set([ab, b]), set(with_b), "Search for category_id in cat_b failed.")
+
+        with_a_or_b = partners.search(cr, uid, [('category_id', 'in', [cat_a, cat_b])])
+        self.assertEqual(set([ab, a, b]), set(with_a_or_b), "Search for category_id contains cat_a or cat_b failed.")
+
+        with_a_and_b = partners.search(cr, uid, [('category_id', 'in', [cat_a]), ('category_id', 'in', [cat_b])])
+        self.assertEqual(set([ab]), set(with_a_and_b), "Search for category_id contains cat_a and cat_b failed.")
+
+        # Note it is the same as with_a_or_b above.
+        with_a_or_with_b = partners.search(cr, uid, ['|', ('category_id', 'in', [cat_a]), ('category_id', 'in', [cat_b])])
+        self.assertEqual(set([ab, a, b]), set(with_a_or_with_b), "Search for category_id contains cat_a or contains cat_b failed.")
+
+        without_a_or_b = partners.search(cr, uid, [('category_id', 'not in', [cat_a, cat_b])])
+        self.assertTrue(all(i not in without_a_or_b for i in [a, b, ab]), "Search for category_id doesn't contain cat_a or cat_b failed (1).")
+        self.assertTrue(c in without_a_or_b, "Search for category_id doesn't contain cat_a or cat_b failed (2).")
+
+        without_a_and_without_b = partners.search(cr, uid, [('category_id', 'not in', [cat_a]), ('category_id', 'not in', [cat_b])])
+        self.assertTrue(all(i not in without_a_and_without_b for i in [a, b, ab]), "Search for category_id doesn't contain cat_a and cat_b failed (1).")
+        self.assertTrue(c in without_a_and_without_b, "Search for category_id doesn't contain cat_a and cat_b failed (2).")
+
+        without_a = partners.search(cr, uid, [('category_id', 'not in', [cat_a])])
+        self.assertTrue(a not in without_a, "Search for category_id doesn't contain cat_a failed (1).")
+        self.assertTrue(ab not in without_a, "Search for category_id doesn't contain cat_a failed (2).")
+        self.assertTrue(set([b, c]).issubset(set(without_a)), "Search for category_id doesn't contain cat_a failed (3).")
+
+        without_b = partners.search(cr, uid, [('category_id', 'not in', [cat_b])])
+        self.assertTrue(b not in without_b, "Search for category_id doesn't contain cat_b failed (1).")
+        self.assertTrue(ab not in without_b, "Search for category_id doesn't contain cat_b failed (2).")
+        self.assertTrue(set([a, c]).issubset(set(without_b)), "Search for category_id doesn't contain cat_b failed (3).")
+
+        # We can't express the following.
+        # with_any_other_than_a = ...
+        # self.assertTrue(ab in with_any_other_than_a, "Search for category_id with any other than cat_a failed.")
+