ItemScorer base2 = PrecomputedItemScorer.newBuilder()
.addScore(42, 1, 3.0)
.addScore(42, 2, 3.0)
.addScore(42, 3, 3.0)
.build();
ItemScorer scorer = new FallbackItemScorer(primary, base1);
RatingPredictor pred = new SimpleRatingPredictor(scorer, base2, null);
MutableSparseVector vec = MutableSparseVector.create(1, 2, 3);
pred.predict(42, vec);
assertThat(vec.size(), equalTo(3));
assertThat(vec.get(1), equalTo(3.5));