### Question:
FeatureVectorsPartition implements FeatureVectors { @Override public String toString() { return "FeatureVectors[size:" + size() + "]"; } FeatureVectorsPartition(); @Override int size(); @Override float[] getVector(String id); @Override void setVector(String id, float[] vector); @Override void addAllIDsTo(Collection<String> allIDs); @Override void removeAllIDsFrom(Collection<String> allIDs); @Override void addAllRecentTo(Collection<String> allRecent); @Override void retainRecentAndIDs(Collection<String> newModelIDs); void forEach(BiConsumer<String,float[]> action); @Override double[] getVTV(boolean background); @Override String toString();  }### Answer:
@Test public void testToString() { FeatureVectors vectors = new FeatureVectorsPartition(); vectors.setVector("A", new float[]{1.0f, 3.0f, 6.0f}); assertEquals("FeatureVectors[size:1]", vectors.toString()); }