Added a test feature reachable by using `--test 1` to test entries in a local cache4.db file for compatibility.

.gitignore

@@ -7,3 +7,4 @@ data/
 .DS_Store
 .idea
 src/main/main.iml
+cache4.*

src/main/java/de/fabianonline/telegram_backup/CommandLineController.java

@@ -128,6 +128,15 @@ public class CommandLineController {
 				}
 			}
 			
+			if (CommandLineOptions.val_test != null) {
+				if (CommandLineOptions.val_test == 1) {
+					TestFeatures.test1();
+				} else {
+					System.out.println("Unknown test " + CommandLineOptions.val_test);
+				}
+				System.exit(1);
+			}
+			
 			logger.debug("CommandLineOptions.val_export: {}", CommandLineOptions.val_export);
 			if (CommandLineOptions.val_export != null) {
 				if (CommandLineOptions.val_export.toLowerCase().equals("html")) {

src/main/java/de/fabianonline/telegram_backup/CommandLineOptions.java

@@ -33,6 +33,7 @@ class CommandLineOptions {
 	public static Integer val_limit_messages = null;
 	public static String  val_target         = null;
 	public static String  val_export         = null;
+	public static Integer val_test           = null;
 
 	public static void parseOptions(String[] args) {
 		String last_cmd = null;
@@ -51,6 +52,9 @@ class CommandLineOptions {
 						
 					case "--export":
 						val_export = arg;                           break;
+					
+					case "--test":
+						val_test = Integer.parseInt(arg);           break;
 				}
 				last_cmd = null;
 				continue;
@@ -101,6 +105,9 @@ class CommandLineOptions {
 				
 				case "--no-media":
 					cmd_no_media = true;            break;
+				
+				case "--test":
+					last_cmd = "--test";            continue;
 					
 				default:
 					throw new RuntimeException("Unknown command " + arg);

src/main/java/de/fabianonline/telegram_backup/TestFeatures.java

@@ -0,0 +1,54 @@
+package de.fabianonline.telegram_backup;
+
+import com.github.badoualy.telegram.tl.api.*;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.Statement;
+import java.sql.SQLException;
+import java.sql.ResultSet;
+import java.io.IOException;
+
+class TestFeatures {
+	public static void test1() {
+		// Tests entries in a cache4.db in the current working directory for compatibility
+		try {
+			Class.forName("org.sqlite.JDBC");
+		} catch(ClassNotFoundException e) {
+			CommandLineController.show_error("Could not load jdbc-sqlite class.");
+		}
+
+		String path = "jdbc:sqlite:cache4.db";
+
+		Connection conn = null;
+		Statement stmt = null;
+		
+		try {
+			conn = DriverManager.getConnection(path);
+			stmt = conn.createStatement();
+		} catch (SQLException e) {
+			CommandLineController.show_error("Could not connect to SQLITE database.");
+		}
+		
+		int unsupported_constructor = 0;
+		int success = 0;
+		
+		try {
+			ResultSet rs = stmt.executeQuery("SELECT data FROM messages");
+			while (rs.next()) {
+				try {
+					TLApiContext.getInstance().deserializeMessage(rs.getBytes(1));
+				} catch (com.github.badoualy.telegram.tl.exception.UnsupportedConstructorException e) {
+					unsupported_constructor++;
+				} catch (IOException e) {
+					System.out.println("IOException: " + e);
+				}
+				success++;
+			}
+		} catch (SQLException e) {
+			System.out.println("SQL exception: " + e);
+		}
+		
+		System.out.println("Success:                 " + success);
+		System.out.println("Unsupported constructor: " + unsupported_constructor);
+	}
+}