gistfile1.cs

public class ReferenceValuesService{
  
  public ReferenceValuesService(Func<Context> contextFactory){
    this.contextFactory = contextFactory;
    this.referenceValues = new Lazy<IEnumerable<ReferenceValue>>(() => this.contextFactory().GetReferenceValues());
  }
  
  public IEnumerable<ReferenceValue> ReferenceValues(){
    return this.referenceValues.Value;
  }
  
  private readonly Lazy<IEnumerable<ReferenceValue>> referenceValues;
}

public class Context : DbContext{
  public virtual ObjectResult<ReferenceValue> GetReferenceValues(){
    //Entity Framework cruft
  }
}

// instantiate ReferenceValuesService as new ReferenceValuesService(() => new Context())