### Question:
DiffObjectCount { public @Override String toString() { StringBuilder b = new StringBuilder(); b.append("trees [ added: ").append(treesAdded).append(", changed: ").append(treesChanged) .append(", removed: ").append(treesRemoved).append("]\n"); b.append("features[ added: ").append(featuresAdded).append(", changed: ") .append(featuresChanged).append(", removed: ").append(featuresRemoved).append("]"); return b.toString(); } DiffObjectCount(); @Override String toString(); long count(); long featureCount(); int treeCount(); long addedFeatures(long count); long removedFeatures(long count); long changedFeatures(long count); int addedTrees(int count); int removedTrees(int count); int changedTrees(int count); long getFeaturesAdded(); long getFeaturesRemoved(); long getFeaturesChanged(); int getTreesAdded(); int getTreesRemoved(); int getTreesChanged();  }### Answer:
@Test public void testToString() { DiffObjectCount count = new DiffObjectCount(); count.addedFeatures(1); count.changedFeatures(2); count.removedFeatures(3); count.addedTrees(4); count.changedTrees(5); count.removedTrees(6); String expected = "trees [ added: 4, changed: 5, removed: 6]\n" + "features[ added: 1, changed: 2, removed: 3]"; assertEquals(expected, count.toString()); }