Core Test Support

/**
 * Core test support class for managing Dropwizard application lifecycle
 * @param <C> Configuration type extending Configuration
 */
public class DropwizardTestSupport<C extends Configuration> {
    
    // Primary constructors
    public DropwizardTestSupport(Class<? extends Application<C>> applicationClass,
                                @Nullable String configPath,
                                ConfigOverride... configOverrides);
    
    public DropwizardTestSupport(Class<? extends Application<C>> applicationClass,
                                C configuration);
    
    // Extended constructors
    public DropwizardTestSupport(Class<? extends Application<C>> applicationClass,
                                @Nullable String configPath,
                                @Nullable ConfigurationSourceProvider configSourceProvider,
                                ConfigOverride... configOverrides);
    
    public DropwizardTestSupport(Class<? extends Application<C>> applicationClass,
                                @Nullable String configPath,
                                @Nullable String customPropertyPrefix,
                                ConfigOverride... configOverrides);
    
    public DropwizardTestSupport(Class<? extends Application<C>> applicationClass,
                                @Nullable C configuration,
                                Function<Application<C>, Command> commandInstantiator);
    
    // Lifecycle management
    /**
     * Initialize and start the Dropwizard application before tests
     * @throws Exception if application startup fails
     */
    public void before() throws Exception;
    
    /**
     * Stop and cleanup the Dropwizard application after tests
     */
    public void after();
    
    // Application access
    /**
     * Get the application configuration instance
     * @return Configuration object used by the application
     */
    public C getConfiguration();
    
    /**
     * Get the running Dropwizard application instance
     * @return Application instance with full type information
     */
    public <A extends Application<C>> A getApplication();
    
    /**
     * Virtual constructor for creating custom application instances
     * Can be overridden for specialized application initialization
     * @return New application instance
     */
    public Application<C> newApplication();
    
    /**
     * Get the Dropwizard runtime environment
     * @return Environment instance with access to metrics, validation, etc.
     */
    public Environment getEnvironment();
    
    /**
     * Get the Jackson ObjectMapper used by the application
     * @return ObjectMapper for JSON/YAML processing
     */
    public ObjectMapper getObjectMapper();
    
    // Network access
    /**
     * Get the main application HTTP port
     * @return Port number for application endpoints
     */
    public int getLocalPort();
    
    /**
     * Get the admin interface HTTP port
     * @return Port number for admin endpoints
     */
    public int getAdminPort();
    
    /**
     * Get the port for a specific connector by index
     * @param connectorIndex Zero-based connector index
     * @return Port number for the specified connector
     */
    public int getPort(int connectorIndex);
    
    // Configuration and extension
    /**
     * Add a lifecycle listener for application events
     * @param listener ServiceListener instance for handling events
     * @return This DropwizardTestSupport instance for chaining
     */
    public DropwizardTestSupport<C> addListener(ServiceListener<C> listener);
    
    /**
     * Add a managed object to the application lifecycle
     * @param managed Managed object to start/stop with application
     * @return This DropwizardTestSupport instance for chaining
     */
    public DropwizardTestSupport<C> manage(Managed managed);
}

// Basic application testing with config file
DropwizardTestSupport<MyConfiguration> testSupport = 
    new DropwizardTestSupport<>(
        MyApplication.class,
        ResourceHelpers.resourceFilePath("test-config.yml")
    );

testSupport.before(); // Start application
try {
    // Test application
    int port = testSupport.getLocalPort();
    MyConfiguration config = testSupport.getConfiguration();
    Environment env = testSupport.getEnvironment();
    
    // Make HTTP requests, test components, etc.
} finally {
    testSupport.after(); // Stop application
}

// With configuration overrides and random ports
DropwizardTestSupport<MyConfiguration> testSupport = 
    new DropwizardTestSupport<>(
        MyApplication.class,
        ResourceHelpers.resourceFilePath("test-config.yml"),
        ConfigOverride.randomPorts(),
        ConfigOverride.config("database.url", "jdbc:h2:mem:test")
    );

// With pre-built configuration object
MyConfiguration config = new MyConfiguration();
config.setDatabaseUrl("jdbc:h2:mem:test");

DropwizardTestSupport<MyConfiguration> testSupport = 
    new DropwizardTestSupport<>(MyApplication.class, config);

// With lifecycle listener
testSupport.addListener(new ServiceListener<MyConfiguration>() {
    @Override
    public void onRun(MyConfiguration configuration, 
                     Environment environment, 
                     DropwizardTestSupport<MyConfiguration> rule) {
        // Setup test data, mock services, etc.
    }
    
    @Override
    public void onStop(DropwizardTestSupport<MyConfiguration> rule) {
        // Cleanup test resources
    }
});

/**
 * Abstract listener for application lifecycle events
 * @param <T> Configuration type extending Configuration
 */
public abstract static class ServiceListener<T extends Configuration> {
    
    /**
     * Called when the application has started and is ready for testing
     * @param configuration Application configuration instance
     * @param environment Dropwizard environment instance  
     * @param rule DropwizardTestSupport instance managing the application
     * @throws Exception if setup fails
     */
    public void onRun(T configuration, Environment environment, 
                     DropwizardTestSupport<T> rule) throws Exception {
        // Override for custom setup logic
    }
    
    /**
     * Called when the application is stopping after tests complete
     * @param rule DropwizardTestSupport instance managing the application
     * @throws Exception if cleanup fails
     */
    public void onStop(DropwizardTestSupport<T> rule) throws Exception {
        // Override for custom cleanup logic
    }
}

/**
 * Configuration factory using pre-built configuration objects
 * @param <C> Configuration type extending Configuration
 */
public class POJOConfigurationFactory<C extends Configuration> 
    extends YamlConfigurationFactory<C> {
    
    /**
     * Create factory with pre-built configuration
     * @param cfg Configuration object to return for all build() calls
     */
    public POJOConfigurationFactory(C cfg);
    
    /**
     * Returns the pre-configured object, ignoring provider and path
     * @param provider Ignored configuration source provider
     * @param path Ignored configuration path
     * @return The pre-configured configuration object
     */
    public C build(ConfigurationSourceProvider provider, String path);
    
    /**
     * Returns the pre-configured object, ignoring file parameter
     * @param file Ignored configuration file
     * @return The pre-configured configuration object
     */
    public C build(File file);
    
    /**
     * Returns the pre-configured object
     * @return The pre-configured configuration object
     */
    public C build();
}

/**
 * Utility class for classpath resource operations
 */
public class ResourceHelpers {
    
    /**
     * Convert a classpath resource location to an absolute file path
     * Useful for loading test configuration files from classpath
     * @param resourceClassPathLocation Classpath location (e.g., "test-config.yml")
     * @return Absolute file path to the resource
     */
    public static String resourceFilePath(String resourceClassPathLocation);
}

// Load test configuration from classpath
String configPath = ResourceHelpers.resourceFilePath("test-config.yml");
DropwizardTestSupport<MyConfiguration> testSupport = 
    new DropwizardTestSupport<>(MyApplication.class, configPath);

// Use with different test configurations
String devConfigPath = ResourceHelpers.resourceFilePath("configs/dev-test.yml");
String integrationConfigPath = ResourceHelpers.resourceFilePath("configs/integration-test.yml");