### Question:
ConstantCompletion implements Completion { @Nonnull @Override public String getSortOrderPrefix() { return CONSTANTS.prefix; }  @Nonnull @Override Collection<String> getCompletionSource(MyDocumentModel document); @Nonnull @Override String getSortOrderPrefix(); @Nonnull @Override CompletionItemKind getKind();  }### Answer:
@Test void getSortOrderPrefix() { assertEquals("3", completion.getSortOrderPrefix()); }