Test cases and checkstyle done

src/main/java/seedu/billboard/commons/core/Messages.java

@@ -12,4 +12,6 @@ public class Messages {
     public static final String MESSAGE_NONEXISTENT_ARCHIVE_ENTERED =
             "There is no existing archive of the name provided";
     public static final String MESSAGE_INVALID_ARCHIVE_NAME = "The archive name cannot be empty!";
+    public static final String MESSAGE_NOT_UNDOABLE = "There is no command to be undone.";
+    public static final String MESSAGE_NOT_REDOABLE = "There is no command to be redone.";
 }

src/main/java/seedu/billboard/commons/core/observable/ObservableData.java

@@ -71,11 +71,4 @@ public void setObservers(Set<Observer<? super T>> observers) {
         this.observers.addAll(observers);
     }
 
-    public ObservableData getClone() {
-        ObservableData<T> clonedData = new ObservableData<>();
-        clonedData.setValue(value);
-        clonedData.setObservers(observers);
-        return clonedData;
-    }
-
 }

src/main/java/seedu/billboard/logic/commands/HistoryCommand.java

@@ -1,6 +1,5 @@
 package seedu.billboard.logic.commands;
 
-import seedu.billboard.logic.commands.exceptions.CommandException;
 import seedu.billboard.model.Model;
 import seedu.billboard.model.history.CommandHistory;
 
@@ -9,20 +8,19 @@
  */
 public class HistoryCommand extends Command {
     public static final String COMMAND_WORD = "history";
-    public static final String EMPTY_HISTORY = "There is no commandHistory.";
+    public static final String MESSAGE_EMPTY_HISTORY = "There is no command history.";
 
 
     /**
      * Executes the command and returns the result message.
      *
      * @param model {@code Model} which the command should operate on.
      * @return feedback message of the operation result for display
-     * @throws CommandException If an error occurs during command execution.
      */
     @Override
-    public CommandResult execute(Model model) throws CommandException {
+    public CommandResult execute(Model model) {
         if (!CommandHistory.hasCommand()) {
-            CommandResult cmdResult = new CommandResult(EMPTY_HISTORY);
+            return new CommandResult(MESSAGE_EMPTY_HISTORY);
         }
 
         CommandResult cmdResult = new CommandResult(CommandHistory.getCmdHistory());

src/main/java/seedu/billboard/logic/commands/RedoCommand.java

@@ -11,6 +11,7 @@ public class RedoCommand extends Command {
 
     public static final String COMMAND_WORD = "redo";
     public static final String EMPTY_UNDO_LIST = "There is no command to be redone.";
+    public static final String MESSAGE_REDO_SUCCESS = COMMAND_WORD + ": %s";
 
     /**
      * Executes the command and returns the result message.
@@ -28,7 +29,7 @@ public CommandResult execute(Model model) throws CommandException {
         String redoCmd = VersionedBillboard.getRedoCmd();
         Model undoModel = VersionedBillboard.redo();
         model.setModel(undoModel);
-        CommandResult cmdResult = new CommandResult(COMMAND_WORD + ": " + redoCmd);
+        CommandResult cmdResult = new CommandResult(String.format(MESSAGE_REDO_SUCCESS, redoCmd));
         return cmdResult;
     }
 }

src/main/java/seedu/billboard/logic/commands/UndoCommand.java

@@ -11,6 +11,7 @@ public class UndoCommand extends Command {
 
     public static final String COMMAND_WORD = "undo";
     public static final String EMPTY_UNDO_LIST = "There is no command to be undone.";
+    public static final String MESSAGE_UNDO_SUCCESS = COMMAND_WORD + ": %s";
 
     /**
      * Executes the command and returns the result message.
@@ -28,7 +29,7 @@ public CommandResult execute(Model model) throws CommandException {
         Model undoModel = VersionedBillboard.undo();
         String undoCmd = VersionedBillboard.getUndoCmd();
         model.setModel(undoModel);
-        CommandResult cmdResult = new CommandResult(COMMAND_WORD + ": " + undoCmd);
+        CommandResult cmdResult = new CommandResult(String.format(MESSAGE_UNDO_SUCCESS, undoCmd));
         return cmdResult;
     }
 }

src/main/java/seedu/billboard/logic/parser/BillboardParser.java

@@ -80,13 +80,13 @@ public Command parseCommand(String userInput) throws ParseException {
             return new TagCommandParser().parse(arguments);
 
         case UndoCommand.COMMAND_WORD:
-            return new UndoCommandParser().parse(arguments);
+            return new UndoCommand();
 
         case RedoCommand.COMMAND_WORD:
-            return new RedoCommandParser().parse(arguments);
+            return new RedoCommand();
 
         case HistoryCommand.COMMAND_WORD:
-            return new HistoryCommandParser().parse(arguments);
+            return new HistoryCommand();
 
         default:
             throw new ParseException(MESSAGE_UNKNOWN_COMMAND);

src/main/java/seedu/billboard/model/ModelManager.java

@@ -69,17 +69,6 @@ public ModelManager() {
         this(new Billboard(), new UserPrefs());
     }
 
-    public ModelManager(Billboard billboard, ArchiveWrapper archives, UserPrefs userPrefs,
-                        ObservableData<StatisticsType> statsType, FilteredList<Expense> filteredExpense,
-                        HashMap<String, FilteredList<Expense>> filteredArchives) {
-        this.billboard = billboard;
-        this.archives = archives;
-        this.userPrefs = userPrefs;
-        this.statsType = statsType;
-        this.filteredExpense = filteredExpense;
-        this.filteredArchives = filteredArchives;
-    }
-
     @Override
     public Billboard getCombinedBillboard() {
         List<Expense> combinedExpenses = new ArrayList<>();

src/main/java/seedu/billboard/model/history/CommandHistory.java

@@ -6,7 +6,7 @@
  * Object to store all the executed command.
  */
 public class CommandHistory {
-    public static final String HAVE_HISTORY = "The following is the command history:";
+    public static final String HAVE_HISTORY = "The following is the command history:%s";
     private static Stack<String> cmdList = new Stack<>();
     private static int count = 0;
 
@@ -63,7 +63,7 @@ public static String peekPreviousCmd() {
      * @return boolean return true if the cmdList is not empty.
      */
     public static boolean hasCommand() {
-        return !cmdList.empty();
+        return cmdList.size() != 1;
     }
 
     /**
@@ -72,11 +72,19 @@ public static boolean hasCommand() {
      * @return String return the string containing all the history commands.
      */
     public static String getCmdHistory() {
-        String result = HAVE_HISTORY;
+        String result = "";
         for (int i = cmdList.size() - 1; i > 0; i--) {
             result = result.concat("\n\t");
             result = result.concat(cmdList.get(i - 1));
         }
-        return result;
+        return String.format(HAVE_HISTORY, result);
+    }
+
+    /**
+     * Clear command history.
+     */
+    public static void clearHistory() {
+        cmdList.clear();
+        count = 0;
     }
 }

src/main/java/seedu/billboard/model/versionedbillboard/VersionedBillboard.java

@@ -8,9 +8,9 @@
  * Undo command List, store the previous model and command.
  */
 public class VersionedBillboard {
-    protected static Stack<Model> modelList = new Stack<>();
-    protected static Stack<String> cmdList = new Stack<>();
-    protected static int currentState = 0;
+    private static Stack<Model> modelList = new Stack<>();
+    private static Stack<String> cmdList = new Stack<>();
+    private static int currentState = 0;
 
     /**
      * Saves the current address book state in state history.
@@ -68,7 +68,17 @@ public static String getRedoCmd() {
     public static void clearList() {
         modelList.clear();
         cmdList.clear();
+        currentState = 0;
     }
 
+    /**
+     * Compare the history of two Billboard states.
+     */
+    public boolean compareBillboardModels(Stack<Model> modelList) {
+        return VersionedBillboard.modelList.equals(modelList);
+    }
 
+    public static void setCurrentState(int currentState) {
+        VersionedBillboard.currentState = currentState;
+    }
 }

src/test/java/seedu/billboard/logic/LogicManagerTest.java

@@ -27,7 +27,6 @@
 import seedu.billboard.model.ReadOnlyBillboard;
 import seedu.billboard.model.UserPrefs;
 import seedu.billboard.model.expense.Expense;
-import seedu.billboard.model.versionedbillboard.VersionedBillboard;
 import seedu.billboard.storage.JsonBillboardStorage;
 import seedu.billboard.storage.JsonUserPrefsStorage;
 import seedu.billboard.storage.StorageManager;
@@ -41,7 +40,6 @@ public class LogicManagerTest {
 
     private Model model = new ModelManager();
     private Logic logic;
-    private VersionedBillboard versionedBillboard = new VersionedBillboard();
 
     @BeforeEach
     public void setUp() {

src/test/java/seedu/billboard/logic/commands/HistoryCommandTest.java

@@ -0,0 +1,35 @@
+package seedu.billboard.logic.commands;
+
+import static seedu.billboard.logic.commands.CommandTestUtil.assertCommandSuccess;
+import static seedu.billboard.testutil.TypicalExpenses.getTypicalBillboard;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import seedu.billboard.model.Model;
+import seedu.billboard.model.ModelManager;
+import seedu.billboard.model.UserPrefs;
+import seedu.billboard.model.history.CommandHistory;
+
+
+
+class HistoryCommandTest {
+    private Model model;
+
+    @BeforeEach
+    public void setUp() {
+        model = new ModelManager(getTypicalBillboard(), new UserPrefs());
+        CommandHistory.clearHistory();
+        CommandHistory.addCmdHistory("history");
+    }
+
+    @Test
+    void execute() {
+        //Empty history -> empty history message
+        HistoryCommand historyCommand = new HistoryCommand();
+        assertCommandSuccess(historyCommand, model, HistoryCommand.MESSAGE_EMPTY_HISTORY, model);
+        //Not empty history -> history records
+        CommandHistory.addCmdHistory("history");
+        assertCommandSuccess(historyCommand, model, String.format(CommandHistory.HAVE_HISTORY, "\n\thistory"), model);
+    }
+}

src/test/java/seedu/billboard/logic/commands/RedoCommandTest.java

@@ -0,0 +1,41 @@
+package seedu.billboard.logic.commands;
+
+import static seedu.billboard.logic.commands.CommandTestUtil.assertCommandFailure;
+import static seedu.billboard.logic.commands.CommandTestUtil.assertCommandSuccess;
+import static seedu.billboard.testutil.TypicalExpenses.getDeleteTypicalBillboard;
+import static seedu.billboard.testutil.TypicalExpenses.getTypicalBillboard;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import seedu.billboard.commons.core.Messages;
+import seedu.billboard.model.Model;
+import seedu.billboard.model.ModelManager;
+import seedu.billboard.model.UserPrefs;
+import seedu.billboard.model.versionedbillboard.VersionedBillboard;
+
+class RedoCommandTest {
+    private Model model;
+    private RedoCommand redo;
+
+    @BeforeEach
+    void setUp() {
+        model = new ModelManager(getTypicalBillboard(), new UserPrefs());
+        VersionedBillboard.clearList();
+        VersionedBillboard.commit(model);
+        redo = new RedoCommand();
+    }
+
+    @Test
+    void execute() {
+        assertCommandFailure(redo, model, Messages.MESSAGE_NOT_REDOABLE);
+        Model deleteModel = new ModelManager(getDeleteTypicalBillboard(), new UserPrefs());
+        VersionedBillboard.commit(deleteModel);
+        String deleteCmd = "delete 1";
+        VersionedBillboard.addCmd(deleteCmd);
+        VersionedBillboard.undo();
+
+        String expectedMessage = String.format(RedoCommand.MESSAGE_REDO_SUCCESS, deleteCmd);
+        assertCommandSuccess(redo, model, expectedMessage, deleteModel);
+    }
+}

src/test/java/seedu/billboard/logic/commands/UndoCommandTest.java

@@ -0,0 +1,34 @@
+package seedu.billboard.logic.commands;
+
+import static seedu.billboard.logic.commands.CommandTestUtil.assertCommandFailure;
+import static seedu.billboard.logic.commands.CommandTestUtil.assertCommandSuccess;
+import static seedu.billboard.testutil.TypicalExpenses.getDeleteTypicalBillboard;
+import static seedu.billboard.testutil.TypicalExpenses.getTypicalBillboard;
+
+import org.junit.jupiter.api.Test;
+
+import seedu.billboard.commons.core.Messages;
+import seedu.billboard.model.Model;
+import seedu.billboard.model.ModelManager;
+import seedu.billboard.model.UserPrefs;
+import seedu.billboard.model.versionedbillboard.VersionedBillboard;
+
+class UndoCommandTest {
+
+    @Test
+    void execute() {
+        Model model = new ModelManager(getTypicalBillboard(), new UserPrefs());
+        Model deleteModel = new ModelManager(getDeleteTypicalBillboard(), new UserPrefs());
+        Model expectedModel = new ModelManager(model.getBillboard(), new UserPrefs());
+        VersionedBillboard.clearList();
+        VersionedBillboard.commit(model);
+        UndoCommand undo = new UndoCommand();
+        assertCommandFailure(undo, model, Messages.MESSAGE_NOT_UNDOABLE);
+        VersionedBillboard.commit(deleteModel);
+        String deleteCmd = "delete 1";
+        VersionedBillboard.addCmd(deleteCmd);
+        String expectedMessage = String.format(UndoCommand.MESSAGE_UNDO_SUCCESS, deleteCmd);
+        assertCommandSuccess(undo, deleteModel, expectedMessage, expectedModel);
+    }
+
+}