### Question:
IdFieldEmittableKey extends EmittableKey { @Override public String toString() { return "IdFieldEmittableKey [" + getIdField() + "=" + getId().toString() + "]"; } IdFieldEmittableKey();  IdFieldEmittableKey(final String mongoFieldName); Text getIdField(); Text getId(); void setId(final Text value); @Override void readFields(DataInput data); @Override void write(DataOutput data); @Override String toString(); @Override BSONObject toBSON(); @Override int hashCode(); @Override boolean equals(Object obj); @Override int compareTo(EmittableKey other);  }### Answer:
@Test public void testToString() { IdFieldEmittableKey key = new IdFieldEmittableKey("test.id.key.field"); key.setId(new Text("1234")); assertEquals(key.toString(), "IdFieldEmittableKey [test.id.key.field=1234]"); }