public class ModifyTest {
  
  @Test
  public void testModify() {
    ...
    session.insert(new Passport("CA-SARAH-1", LocalDate.of(2017, 1, 17)));
    session.insert(new VisaApplication(1, "CA-SARAH-1"));
    
    session.fireAllRules();
    
    assertTrue(session.getObjects((Object object) -> {
      return object instanceof String;
    }).isEmpty());
  }
}

dialect "mvel"

import Passport;
import Validation;
import VisaApplication;

rule "Expired passport"
  salience 3
  when
    $passport: Passport( expired == true )
  then
    System.out.println( $passport + " is INVALID because it is expired" );
    modify($passport) {
      setValidation( Validation.FAILED ),
      setCause( "passport is expired" )
    }
end

rule "Invalidate visa application with invalid passport"
  salience 2
  when
    $passport: Passport( validation == Validation.FAILED )
    $visaApplication: VisaApplication( passportNumber == $passport.passportNumber, validation != Validation.FAILED )
  then
    System.out.println( "Set " + $visaApplication + " invalid as " + $passport + " hasn't passed validation");
    modify($visaApplication) {
      setValidation( Validation.FAILED )
    }
end

rule "Set application without validation info as passed"
  salience 1
  when
    $visaApplication: VisaApplication( validation == Validation.UNKNOWN )
  then
    System.out.println( $visaApplication + " is without validation info, consider OK for now" );
    modify($visaApplication) {
      setValidation( Validation.PASSED )
    }
    insert ("fail");
end

import static Validation.UNKNOWN;
import static java.lang.String.format;

import java.time.LocalDate;

public class Passport {
  private String passportNumber;
  private LocalDate expiresOn;
  private Validation validation = UNKNOWN;
  
  private String cause = "";
  
  public Passport(String passportNumber, LocalDate expiresOn) {
    this.passportNumber = passportNumber;
    this.expiresOn = expiresOn;
  }
  
  public boolean isExpired() {
    return expiresOn.isBefore(LocalDate.now());
  }
  
  public String getPassportNumber() {
    return passportNumber;
  }
  
  public Validation getValidation() {
    return validation;
  }
  
  public void setValidation(Validation validation) {
    this.validation = validation;
  }
  
  public String getCause() {
    return cause;
  }
  
  public void setCause(String cause) {
    this.cause = cause;
  }
  
  @Override
  public String toString() {
    return format("Passport[no:%s]", passportNumber);
  }
}

import static Validation.UNKNOWN;

public class VisaApplication {
  private int applicationId;
  private String passportNumber;
  private Validation validation = UNKNOWN;
  
  public VisaApplication(int applicationId, String passportNumber) {
    this.applicationId = applicationId;
    this.passportNumber = passportNumber;
  }
  
  public String getPassportNumber() {
    return passportNumber;
  }
  
  public Validation getValidation() {
    return validation;
  }
  
  public void setValidation(Validation validation) {
    this.validation = validation;
  }
  
  @Override
  public String toString() {
    return "VisaApplication(#" + applicationId + ", pass:" + passportNumber + ")";
  }
}

public enum Validation {
	PASSED, FAILED, UNKNOWN
}