Testing with java owner aeonbits

Question

I've been using java OWNER for property based configuration.

I've create a static method

public static final ApplicationConfiguration config = ConfigFactory.create(ApplicationConfiguration.class,
        System.getProperties(), System.getenv());

and I import the class everywhere I need conf.

Needless to say, unit testing is a PITA. I couldn't find a good way of override the values in the configuration.

I would like to avoid passing the config as a dependency in every class. It adds a lot of verbosity and it doesn't make sense from a design point of view. Same applies for calling the config factory in every class

ApplicationConfiguration config = ConfigFactory.create(ApplicationConfiguration.class,
        System.getProperties(), System.getenv());

Have you got any suggestion? is there a best practice?

Answer 1

Two things:

1. You can create a class that provides the properties and all users use it:

   public class PropertiesAccessor {
   
      private static MyConfiguration mMyConfig = ConfigFactory.create(MyConfiguration.class);
   
      private PropertiesAccessor() 
         // No need to allow instantiation of this class
      }
   
      /**
       * Get properties for this application
       *
       * @return Properties
       */
      public static MyConfiguration getProperties() {
         return mMyConfig;
      }
   
      // for unit testing
      @VisibleForTesting
      public static void setProperties(MyConfiguration config) {
         mMyConfig = config;
      }
   }
   

   Now, everywhere you need a property, you can use this static method

   PropertiesAccessor.getProperties()
   

2. Notice that there is a method for testing, setProperties(). There are different ways to use this method. You can create a test property file, load it in, then call the setProperties() method. I like to have a utility method like this:

   public static void initProperties(String fileName) {    
   
      Properties testProperties = new Properties();    
   
      File file = new File(fileName);
      FileInputStream stream = null;   
      try {    
         stream = new FileInputStream(file);   
         testProperties.load(stream);  
      } catch (IOException e) {    
         // Log or whatever you want to do
      } finally {  
         if (stream != null) {
         try { 
            stream.close();    
      } catch (IOException e) {    
        // Log or whatever you want to do; 
      }    
   
      MyConfiguration config = ConfigFactory.create(MyConfiguration.class, testProperties);    
      PropertiesAccessor.setProperties(config);
   }
   

   Then, you can have various properties files.

   Or, if you just want to set a few properties, do this:

    Properties testProperties = new Properties();
    testProperties.setProperty("key1", "data1");
    testProperties.setProperty("key2", "data2");
    final MyConfiguration myConfig = ConfigFactory.create(MyConfiguration.class, testProperties);
    PropertiesAccessor.setProperties(myConfig);