Added the first, trivial tests of weightedUnion and weightedIntersection,

and started repairing obvious errors in their docs.  More to come.

src/BTrees/Interfaces.py

@@ -288,13 +288,11 @@ class IIMerge(IMerge):
     def weightedUnion(c1, c2, weight1=1, weight2=1):
         """Compute the weighted Union of c1 and c2.
 
-        If c1 and c2 are None, the output is 0 and None
+        If c1 and c2 are None, the output is (0, None).
 
-        if c1 is None and c2 is not None, the output is weight2 and
-        c2.
+        If c1 is None and c2 is not None, the output is (weight2, c2).
 
-        if c1 is not None and c2 not None and both sets, the output is 
-        weight1 and c1.
+        If c1 is not None and c2 is None, the output is (weight1, c1).
 
         If c1 and c2 are not None and not both sets, the output is 1
         and a Bucket such that the output values are::
@@ -316,13 +314,11 @@ class IIMerge(IMerge):
     def weightedIntersection(c1, c2, weight1=1, weight2=1):
         """Compute the weighted intersection of c1 and c2.
 
-        If c1 and c2 are None, the output is None, None.
+        If c1 and c2 are None, the output is (0, None).
 
-        if c1 is None and c2 is not None, the output is weight2 and
-        c2.
+        If c1 is None and c2 is not None, the output is (weight2, c2).
 
-        if c1 is not None and c2 not None, the output is weight1 and
-        c1.
+        If c1 is not None and c2 is None, the output is (weight1, c1).
 
         If c1 and c2 are both sets, the output is the sum of the weights
         and the (unweighted) intersection of the sets.

src/BTrees/tests/testSetOps.py

@@ -327,12 +327,73 @@ class TestImports(TestCase):
         else:
             self.fail("OOBTree shouldn't have multiunion")
 
+# Subclasses must set up (as class variables):
+#     weightedUnion, weightedIntersection
+#     builders -- sequence of constructors, taking items
+class Weighted(TestCase):
+
+    def setUp(self):
+        self.Aitems = [(1, 10), (3, 30),  (5, 50), (6, 60)]
+        self.Bitems = [(2, 21), (3, 31), (4, 41),  (6, 61), (7, 71)]
+
+        self.As = [make(self.Aitems) for make in self.builders]
+        self.Bs = [make(self.Bitems) for make in self.builders]
+        self.emptys = [make([]) for make in self.builders]
+
+    def testBothNone(self):
+        for op in self.weightedUnion, self.weightedIntersection:
+            w, C = op(None, None)
+            self.assert_(C is None)
+            self.assertEqual(w, 0)
+
+            w, C = op(None, None, 42, 666)
+            self.assert_(C is None)
+            self.assertEqual(w, 0)
+
+    def testLeftNone(self):
+        for op in self.weightedUnion, self.weightedIntersection:
+            for A in self.As + self.emptys:
+                w, C = op(None, A)
+                self.assert_(C is A)
+                self.assertEqual(w, 1)
+
+                w, C = op(None, A, 42, 666)
+                self.assert_(C is A)
+                self.assertEqual(w, 666)
+
+    def testRightNone(self):
+        for op in self.weightedUnion, self.weightedIntersection:
+            for A in self.As + self.emptys:
+                w, C = op(A, None)
+                self.assert_(C is A)
+                self.assertEqual(w, 1)
+
+                w, C = op(A, None, 42, 666)
+                self.assert_(C is A)
+                self.assertEqual(w, 42)
+
+# Given a set builder (like OITreeSet or OISet), return a function that
+# takes a list of (key, value) pairs and builds a set out of the keys.
+def itemsToSet(setbuilder):
+    def result(items, setbuilder=setbuilder):
+        return setbuilder([key for key, value in items])
+    return result
+
+class TestWeightedII(Weighted):
+    from BTrees.IIBTree import weightedUnion, weightedIntersection
+    builders = IIBucket, IIBTree, itemsToSet(IISet), itemsToSet(IITreeSet)
+
+class TestWeightedOI(Weighted):
+    from BTrees.OIBTree import weightedUnion, weightedIntersection
+    builders = OIBucket, OIBTree, itemsToSet(OISet), itemsToSet(OITreeSet)
+
 
 def test_suite():
     s = TestSuite()
     for klass in (TestIIMultiUnion, TestIOMultiUnion,
                   TestImports,
-                  PureII, PureIO, PureOI, PureOO):
+                  PureII, PureIO, PureOI, PureOO,
+                  TestWeightedII, TestWeightedOI):
         s.addTest(makeSuite(klass))
     return s