serialize object for unit testing

Question

Assuming in a unit test I need to have an object all of 50 fields of which are set up with some values. I don't want to manually set up all this fields, as it takes time and annoying...

Somehow I need to get an instance where all the fields are initialized by some not-null values.

and I had an idea - what if I will debug some code, at some point i will get a working instance of this object with some data set up - and I just will serialize it to the disk.

Then I will put this file to test-resources folder, and in unit tests will just deserialize it from that location.

Sounds feasible.. and reasonable? Is there any other idea, or how would you do that?

UPD: I agree serialization is not good in that case. 1) Saved object is not human readable 2) Version could change (highly unlikely) and is not a big problem I believe... So, maybe are there any readable easy-for-serialization formats?

Ideally I would like to have actually source code to be generated. Because it is a java bean, all the getters/setters are there. Why not generate the set of setters calls over the given object in runtime?

Answer 1

This problem has been solved: https://github.com/bbottema/lorem-ipsum-objects

Answer 2

It will work but it's Nasty with a capital N.

The problem is, when somebody reads the code it's hard to see just what values are being used - given code is read many more times than it's written you should optimise for reading.

Other things that spring to mind:

• testing is all about the boundaries, if you're just using a single set of values, how can your test hit those boundaries?
• does every test need all 50 values, is so there could be something else wrong with your design

If all 50 values do need setting in every test, a common way to make it easier is to use a factory method or the builder pattern - each sets sensible defaults and allows you to override just the values you need.

Answer 3

Why don't you create a .properties file with the property name exactly as same as your attribute in the class. Read this properties file key/values and call setters using the key by reflection. Here is a basic sample code for doing so:

package consoleouput;

import java.io.FileInputStream; import java.lang.reflect.Method; import java.util.Properties; import java.util.Set;

class Config {  private String a;   private String b;

    public String getA() {      return a;   }

    public void setA(String a) {        this.a = a;     }

    public String getB() {      return b;   }

    public void setB(String b) {        this.b = b;     }

}

public class App {  public static void main(String[] args) {        Properties prop = new Properties();         Config config = new Config();       try {           // load a properties file           prop.load(new FileInputStream("config.properties"));            Set<Object> propKeys = prop.keySet();           for (Object key : propKeys) {
                String keyString = (String) key;
                String keyValue = prop.getProperty((String) key);
                // Make sure you use the key value starting with upper case in
                // properties file
                String keySetterMethod = "set" + keyString;
                System.out.println("Setter method name :" + keySetterMethod);
                // Use reflection to call the method
                Method method = config.getClass().getMethod(keySetterMethod,
                        String.class);

                method.invoke(config, keyValue);            }           System.out.println("Value of a : " + config.getA());            System.out.println("Value of b : " + config.getB());        } catch (Exception e) {             e.printStackTrace();        }   } }

Here is the sample cofig.properties content :

A=test B=rest

NOTE :You may use a csv for generating different objects using the same approach.