From cf71d1f3db8f6a986413e3f1ad533a93b396d58c Mon Sep 17 00:00:00 2001
From: Tan Yuanhong <leotan.yh@gmail.com>
Date: Thu, 17 Oct 2019 13:51:09 +0800
Subject: [PATCH 1/7] Implement CLI for listing and searching available
 commands.

---
 .../seedu/algobase/commons/core/Messages.java |  1 +
 .../seedu/algobase/commons/util/AppUtil.java  | 13 +++++++
 .../algobase/logic/commands/Command.java      | 25 +++++++++++++
 .../algobase/logic/commands/HelpCommand.java  | 36 ++++++++++++++++---
 .../algobase/logic/parser/AlgoBaseParser.java |  2 +-
 .../logic/parser/HelpCommandParser.java       | 27 ++++++++++++++
 6 files changed, 99 insertions(+), 5 deletions(-)
 create mode 100644 src/main/java/seedu/algobase/logic/parser/HelpCommandParser.java

diff --git a/src/main/java/seedu/algobase/commons/core/Messages.java b/src/main/java/seedu/algobase/commons/core/Messages.java
index 51c8099d012..9ab5761a374 100644
--- a/src/main/java/seedu/algobase/commons/core/Messages.java
+++ b/src/main/java/seedu/algobase/commons/core/Messages.java
@@ -14,4 +14,5 @@ public class Messages {
     public static final String MESSAGE_INVALID_TAG_FORMAT = "Invalid tag format! \n";
     public static final String MESSAGE_INVALID_TAG_DISPLAYED_INDEX = "The Tag index provided is invalid";
     public static final String MESSAGE_PLANS_LISTED_OVERVIEW = "%1$d plans listed!";
+    public static final String MESSAGE_INVALID_COMMAND_NAME = "Command %1$s not found!";
 }
diff --git a/src/main/java/seedu/algobase/commons/util/AppUtil.java b/src/main/java/seedu/algobase/commons/util/AppUtil.java
index ae18e698dd8..884ad0ecde8 100644
--- a/src/main/java/seedu/algobase/commons/util/AppUtil.java
+++ b/src/main/java/seedu/algobase/commons/util/AppUtil.java
@@ -36,4 +36,17 @@ public static void checkArgument(Boolean condition, String errorMessage) {
             throw new IllegalArgumentException(errorMessage);
         }
     }
+
+    public static String getClassStringField(Class targetClass, String fieldName) {
+        try {
+            String result = (String) targetClass.getField(fieldName).get("");
+            return result;
+        } catch (NoSuchFieldException e) {
+            throw new AssertionError("Class " + targetClass.getName()
+                + "doesn't have " + fieldName + " field.");
+        } catch (IllegalAccessException e) {
+            throw new AssertionError("Class " + targetClass.getName()
+                + "has non-public " + fieldName + ".");
+        }
+    }
 }
diff --git a/src/main/java/seedu/algobase/logic/commands/Command.java b/src/main/java/seedu/algobase/logic/commands/Command.java
index fa8d92c9517..3c895cc96ff 100644
--- a/src/main/java/seedu/algobase/logic/commands/Command.java
+++ b/src/main/java/seedu/algobase/logic/commands/Command.java
@@ -17,4 +17,29 @@ public abstract class Command {
      */
     public abstract CommandResult execute(Model model) throws CommandException;
 
+    public static final Class[] commandList = {
+        AddCommand.class,
+        AddPlanCommand.class,
+        AddTagCommand.class,
+        AddTagCommand.class,
+        ClearCommand.class,
+        DeleteCommand.class,
+        DeletePlanCommand.class,
+        DeleteTagCommand.class,
+        DeleteTaskCommand.class,
+        DoneTaskCommand.class,
+        EditCommand.class,
+        EditPlanCommand.class,
+        EditTagCommand.class,
+        ExitCommand.class,
+        FindCommand.class,
+        FindPlanCommand.class,
+        HelpCommand.class,
+        ListCommand.class,
+        ListPlanCommand.class,
+        ListTagCommand.class,
+        SortCommand.class,
+        SwitchCommand.class,
+        UndoneTaskCommand.class
+    };
 }
diff --git a/src/main/java/seedu/algobase/logic/commands/HelpCommand.java b/src/main/java/seedu/algobase/logic/commands/HelpCommand.java
index e855b48b58f..457c8ccb448 100644
--- a/src/main/java/seedu/algobase/logic/commands/HelpCommand.java
+++ b/src/main/java/seedu/algobase/logic/commands/HelpCommand.java
@@ -1,5 +1,11 @@
 package seedu.algobase.logic.commands;
 
+import static java.util.Objects.requireNonNull;
+import static seedu.algobase.commons.util.AppUtil.getClassStringField;
+
+import java.util.ArrayList;
+import java.util.List;
+
 import seedu.algobase.model.Model;
 
 /**
@@ -8,15 +14,37 @@
 public class HelpCommand extends Command {
 
     public static final String COMMAND_WORD = "help";
-
     public static final String MESSAGE_USAGE = COMMAND_WORD
             + ": Shows program usage instructions.\n"
-            + "Example: " + COMMAND_WORD;
-
+            + "Parameter:\n"
+            + "COMMAND_NAME (can be empty if you want a list of possible commands)\n"
+            + "Example: " + COMMAND_WORD + "find";
     public static final String SHOWING_HELP_MESSAGE = "Opened help window.";
 
+    public final boolean isListAllCommands;
+    public final Class commandClass;
+
+    public HelpCommand(Class commandClass, boolean isListAllCommands) {
+        this.isListAllCommands = isListAllCommands;
+        if(!isListAllCommands) {
+            requireNonNull(commandClass);
+            this.commandClass = commandClass;
+        } else {
+            this.commandClass = commandClass;
+        }
+    }
+
     @Override
     public CommandResult execute(Model model) {
-        return new CommandResult(SHOWING_HELP_MESSAGE, true, false);
+        if(isListAllCommands) {
+            List<String> commandWords = new ArrayList<>();
+            for(Class command: Command.commandList) {
+                commandWords.add(getClassStringField(command, "COMMAND_WORD"));
+            }
+            return new CommandResult(commandWords.toString(), true, false);
+        } else {
+            String commandUsage = getClassStringField(commandClass, "MESSAGE_USAGE");
+            return new CommandResult(commandUsage, true, false);
+        }
     }
 }
diff --git a/src/main/java/seedu/algobase/logic/parser/AlgoBaseParser.java b/src/main/java/seedu/algobase/logic/parser/AlgoBaseParser.java
index c32d0101325..385e7f0dea7 100644
--- a/src/main/java/seedu/algobase/logic/parser/AlgoBaseParser.java
+++ b/src/main/java/seedu/algobase/logic/parser/AlgoBaseParser.java
@@ -115,7 +115,7 @@ public Command parseCommand(String userInput) throws ParseException {
             return new ExitCommand();
 
         case HelpCommand.COMMAND_WORD:
-            return new HelpCommand();
+            return new HelpCommandParser().parse(arguments);
 
         case AddTagCommand.COMMAND_WORD:
             return new AddTagCommandParser().parse(arguments);
diff --git a/src/main/java/seedu/algobase/logic/parser/HelpCommandParser.java b/src/main/java/seedu/algobase/logic/parser/HelpCommandParser.java
new file mode 100644
index 00000000000..649d72abbe3
--- /dev/null
+++ b/src/main/java/seedu/algobase/logic/parser/HelpCommandParser.java
@@ -0,0 +1,27 @@
+package seedu.algobase.logic.parser;
+
+import static seedu.algobase.commons.core.Messages.MESSAGE_INVALID_COMMAND_NAME;
+import static seedu.algobase.commons.util.AppUtil.getClassStringField;
+
+import seedu.algobase.logic.commands.Command;
+import seedu.algobase.logic.commands.HelpCommand;
+import seedu.algobase.logic.parser.exceptions.ParseException;
+
+public class HelpCommandParser implements Parser<HelpCommand> {
+
+    @Override
+    public HelpCommand parse(String userInput) throws ParseException {
+        String trimmedArgs = userInput.trim();
+        if(trimmedArgs.isEmpty()) {
+            return new HelpCommand(null, true);
+        } else {
+            for(Class command: Command.commandList) {
+                String commandWord = getClassStringField(command, "COMMAND_WORD");
+                if(commandWord.equals(trimmedArgs)) {
+                    return new HelpCommand(command, false);
+                }
+            }
+            throw new ParseException(String.format(MESSAGE_INVALID_COMMAND_NAME, trimmedArgs));
+        }
+    }
+}
\ No newline at end of file

From 574bf408d755ec0b5715ac47734ed4c99e6909b1 Mon Sep 17 00:00:00 2001
From: Tan Yuanhong <leotan.yh@gmail.com>
Date: Thu, 17 Oct 2019 14:06:08 +0800
Subject: [PATCH 2/7] Change GUI behavior for HelpCommand and pass checks

---
 .../algobase/logic/commands/Command.java      | 21 ++++++++-------
 .../algobase/logic/commands/HelpCommand.java  | 26 ++++++++++---------
 .../logic/parser/HelpCommandParser.java       | 11 +++++---
 src/main/resources/view/ResultDisplay.fxml    |  5 ++--
 4 files changed, 34 insertions(+), 29 deletions(-)

diff --git a/src/main/java/seedu/algobase/logic/commands/Command.java b/src/main/java/seedu/algobase/logic/commands/Command.java
index 3c895cc96ff..6e121cc039b 100644
--- a/src/main/java/seedu/algobase/logic/commands/Command.java
+++ b/src/main/java/seedu/algobase/logic/commands/Command.java
@@ -8,16 +8,7 @@
  */
 public abstract class Command {
 
-    /**
-     * 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.
-     */
-    public abstract CommandResult execute(Model model) throws CommandException;
-
-    public static final Class[] commandList = {
+    public static final Class[] COMMAND_LIST = {
         AddCommand.class,
         AddPlanCommand.class,
         AddTagCommand.class,
@@ -42,4 +33,14 @@ public abstract class Command {
         SwitchCommand.class,
         UndoneTaskCommand.class
     };
+
+    /**
+     * 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.
+     */
+    public abstract CommandResult execute(Model model) throws CommandException;
+
 }
diff --git a/src/main/java/seedu/algobase/logic/commands/HelpCommand.java b/src/main/java/seedu/algobase/logic/commands/HelpCommand.java
index 457c8ccb448..8934e0560d7 100644
--- a/src/main/java/seedu/algobase/logic/commands/HelpCommand.java
+++ b/src/main/java/seedu/algobase/logic/commands/HelpCommand.java
@@ -15,18 +15,17 @@ public class HelpCommand extends Command {
 
     public static final String COMMAND_WORD = "help";
     public static final String MESSAGE_USAGE = COMMAND_WORD
-            + ": Shows program usage instructions.\n"
-            + "Parameter:\n"
-            + "COMMAND_NAME (can be empty if you want a list of possible commands)\n"
-            + "Example: " + COMMAND_WORD + "find";
-    public static final String SHOWING_HELP_MESSAGE = "Opened help window.";
+        + ": Shows program usage instructions.\n"
+        + "Parameter:\n"
+        + "COMMAND_NAME (can be empty if you want a list of possible commands)\n"
+        + "Example: " + COMMAND_WORD + "find";
 
-    public final boolean isListAllCommands;
-    public final Class commandClass;
+    private final boolean isListAllCommands;
+    private final Class commandClass;
 
     public HelpCommand(Class commandClass, boolean isListAllCommands) {
         this.isListAllCommands = isListAllCommands;
-        if(!isListAllCommands) {
+        if (!isListAllCommands) {
             requireNonNull(commandClass);
             this.commandClass = commandClass;
         } else {
@@ -36,15 +35,18 @@ public HelpCommand(Class commandClass, boolean isListAllCommands) {
 
     @Override
     public CommandResult execute(Model model) {
-        if(isListAllCommands) {
+        if (isListAllCommands) {
             List<String> commandWords = new ArrayList<>();
-            for(Class command: Command.commandList) {
+            for (Class command : Command.COMMAND_LIST) {
                 commandWords.add(getClassStringField(command, "COMMAND_WORD"));
             }
-            return new CommandResult(commandWords.toString(), true, false);
+            String commandPrompt = "Available commands are: " + commandWords.toString() + "\n"
+                + "More information can be found in the popup window.";
+            return new CommandResult(commandPrompt, true, false);
         } else {
             String commandUsage = getClassStringField(commandClass, "MESSAGE_USAGE");
-            return new CommandResult(commandUsage, true, false);
+            return new CommandResult(commandUsage, false, false);
         }
     }
+
 }
diff --git a/src/main/java/seedu/algobase/logic/parser/HelpCommandParser.java b/src/main/java/seedu/algobase/logic/parser/HelpCommandParser.java
index 649d72abbe3..dc817409b5a 100644
--- a/src/main/java/seedu/algobase/logic/parser/HelpCommandParser.java
+++ b/src/main/java/seedu/algobase/logic/parser/HelpCommandParser.java
@@ -7,21 +7,24 @@
 import seedu.algobase.logic.commands.HelpCommand;
 import seedu.algobase.logic.parser.exceptions.ParseException;
 
+/**
+ * Parses input arguments and creates a new HelpCommand object
+ */
 public class HelpCommandParser implements Parser<HelpCommand> {
 
     @Override
     public HelpCommand parse(String userInput) throws ParseException {
         String trimmedArgs = userInput.trim();
-        if(trimmedArgs.isEmpty()) {
+        if (trimmedArgs.isEmpty()) {
             return new HelpCommand(null, true);
         } else {
-            for(Class command: Command.commandList) {
+            for (Class command : Command.COMMAND_LIST) {
                 String commandWord = getClassStringField(command, "COMMAND_WORD");
-                if(commandWord.equals(trimmedArgs)) {
+                if (commandWord.equals(trimmedArgs)) {
                     return new HelpCommand(command, false);
                 }
             }
             throw new ParseException(String.format(MESSAGE_INVALID_COMMAND_NAME, trimmedArgs));
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/main/resources/view/ResultDisplay.fxml b/src/main/resources/view/ResultDisplay.fxml
index 61bc0918ddb..2dbe5c11ad3 100644
--- a/src/main/resources/view/ResultDisplay.fxml
+++ b/src/main/resources/view/ResultDisplay.fxml
@@ -2,7 +2,6 @@
 
 <?import javafx.scene.control.TextArea?>
 <?import javafx.scene.layout.StackPane?>
-<StackPane fx:id="placeHolder" styleClass="pane-with-border" xmlns="http://javafx.com/javafx/8"
-           xmlns:fx="http://javafx.com/fxml/1">
-  <TextArea fx:id="resultDisplay" editable="false" styleClass="result-display"/>
+<StackPane fx:id="placeHolder" styleClass="pane-with-border" xmlns="http://javafx.com/javafx/11.0.1" xmlns:fx="http://javafx.com/fxml/1">
+  <TextArea fx:id="resultDisplay" editable="false" styleClass="result-display" wrapText="true" />
 </StackPane>

From adf7b4a56d47f4f3e524393e245b2bc74ad734b8 Mon Sep 17 00:00:00 2001
From: Tan Yuanhong <leotan.yh@gmail.com>
Date: Thu, 17 Oct 2019 14:07:35 +0800
Subject: [PATCH 3/7] Fix checkstyle warning in tests

---
 .../model/problem/DescriptionContainsKeywordsPredicateTest.java | 2 +-
 .../model/problem/NameContainsKeywordsPredicateTest.java        | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/test/java/seedu/algobase/model/problem/DescriptionContainsKeywordsPredicateTest.java b/src/test/java/seedu/algobase/model/problem/DescriptionContainsKeywordsPredicateTest.java
index 577187f3cb9..47cd55805ef 100644
--- a/src/test/java/seedu/algobase/model/problem/DescriptionContainsKeywordsPredicateTest.java
+++ b/src/test/java/seedu/algobase/model/problem/DescriptionContainsKeywordsPredicateTest.java
@@ -9,7 +9,7 @@
 
 class DescriptionContainsKeywordsPredicateTest {
 
-    private static String KEYWORD_NOT_IN_QUICK_SORT_DESCRIPTION = "1mP0ss1ble";
+    private static final String KEYWORD_NOT_IN_QUICK_SORT_DESCRIPTION = "1mP0ss1ble";
 
     @Test
     public void test_problemDescriptionContainsKeywords_returnTrue() {
diff --git a/src/test/java/seedu/algobase/model/problem/NameContainsKeywordsPredicateTest.java b/src/test/java/seedu/algobase/model/problem/NameContainsKeywordsPredicateTest.java
index 72b13fde402..9762e106c73 100644
--- a/src/test/java/seedu/algobase/model/problem/NameContainsKeywordsPredicateTest.java
+++ b/src/test/java/seedu/algobase/model/problem/NameContainsKeywordsPredicateTest.java
@@ -9,7 +9,7 @@
 
 class NameContainsKeywordsPredicateTest {
 
-    private static String KEYWORD_NOT_IN_QUICK_SORT_NAME = "1mP0ss1ble";
+    private static final String KEYWORD_NOT_IN_QUICK_SORT_NAME = "1mP0ss1ble";
 
     @Test
     public void test_problemNameContainsKeywords_returnTrue() {

From 5ee42f5f21a4b898d9141b6d1029e0fef90307b0 Mon Sep 17 00:00:00 2001
From: Tan Yuanhong <leotan.yh@gmail.com>
Date: Thu, 17 Oct 2019 15:14:24 +0800
Subject: [PATCH 4/7] Write tests for help command

---
 .../logic/commands/CommandResult.java         |  4 ++
 .../algobase/logic/commands/HelpCommand.java  | 26 +++++++++++++
 .../logic/commands/AddCommandTest.java        |  2 +-
 .../logic/commands/HelpCommandTest.java       | 38 +++++++++++++++++++
 .../logic/parser/CommandParserTestUtil.java   | 38 +++++++++++++++++++
 .../logic/parser/HelpCommandParserTest.java   | 37 ++++++++++++++++++
 6 files changed, 144 insertions(+), 1 deletion(-)
 create mode 100644 src/test/java/seedu/algobase/logic/commands/HelpCommandTest.java
 create mode 100644 src/test/java/seedu/algobase/logic/parser/CommandParserTestUtil.java
 create mode 100644 src/test/java/seedu/algobase/logic/parser/HelpCommandParserTest.java

diff --git a/src/main/java/seedu/algobase/logic/commands/CommandResult.java b/src/main/java/seedu/algobase/logic/commands/CommandResult.java
index 69c5f059498..705a5cd5f49 100644
--- a/src/main/java/seedu/algobase/logic/commands/CommandResult.java
+++ b/src/main/java/seedu/algobase/logic/commands/CommandResult.java
@@ -68,4 +68,8 @@ public int hashCode() {
         return Objects.hash(feedbackToUser, showHelp, exit);
     }
 
+    @Override
+    public String toString() {
+        return "[CommandResult]: " + feedbackToUser;
+    }
 }
diff --git a/src/main/java/seedu/algobase/logic/commands/HelpCommand.java b/src/main/java/seedu/algobase/logic/commands/HelpCommand.java
index 8934e0560d7..aa6d3293967 100644
--- a/src/main/java/seedu/algobase/logic/commands/HelpCommand.java
+++ b/src/main/java/seedu/algobase/logic/commands/HelpCommand.java
@@ -23,6 +23,14 @@ public class HelpCommand extends Command {
     private final boolean isListAllCommands;
     private final Class commandClass;
 
+    public boolean isListAllCommands() {
+        return isListAllCommands;
+    }
+
+    public Class getCommandClass() {
+        return commandClass;
+    }
+
     public HelpCommand(Class commandClass, boolean isListAllCommands) {
         this.isListAllCommands = isListAllCommands;
         if (!isListAllCommands) {
@@ -42,6 +50,7 @@ public CommandResult execute(Model model) {
             }
             String commandPrompt = "Available commands are: " + commandWords.toString() + "\n"
                 + "More information can be found in the popup window.";
+            System.out.println(commandPrompt);
             return new CommandResult(commandPrompt, true, false);
         } else {
             String commandUsage = getClassStringField(commandClass, "MESSAGE_USAGE");
@@ -49,4 +58,21 @@ public CommandResult execute(Model model) {
         }
     }
 
+    @Override
+    public boolean equals(Object other) {
+        // short circuit if same object
+        if (other == this) {
+            return true;
+        }
+
+        // instanceof handles nulls
+        if (!(other instanceof HelpCommand)) {
+            return false;
+        }
+
+        // state check
+        HelpCommand h = (HelpCommand) other;
+        return isListAllCommands == h.isListAllCommands()
+            && commandClass.equals(h.getCommandClass());
+    }
 }
diff --git a/src/test/java/seedu/algobase/logic/commands/AddCommandTest.java b/src/test/java/seedu/algobase/logic/commands/AddCommandTest.java
index 6eafeb70f50..526f2b4f639 100644
--- a/src/test/java/seedu/algobase/logic/commands/AddCommandTest.java
+++ b/src/test/java/seedu/algobase/logic/commands/AddCommandTest.java
@@ -23,7 +23,7 @@ public void constructor_nullProblem_throwsNullPointerException() {
     }
 
     @Test
-    public void execute_problemAcceptedByModel_addSuccessful() throws Exception {
+    public void execute_problemAcceptedByModel_addsSuccessful() throws Exception {
         ModelStubAcceptingProblemAdded modelStub = new ModelStubAcceptingProblemAdded();
         Problem validProblem = new ProblemBuilder().build();
 
diff --git a/src/test/java/seedu/algobase/logic/commands/HelpCommandTest.java b/src/test/java/seedu/algobase/logic/commands/HelpCommandTest.java
new file mode 100644
index 00000000000..eb24dcc84c9
--- /dev/null
+++ b/src/test/java/seedu/algobase/logic/commands/HelpCommandTest.java
@@ -0,0 +1,38 @@
+package seedu.algobase.logic.commands;
+
+import static seedu.algobase.logic.commands.CommandTestUtil.assertCommandSuccess;
+import static seedu.algobase.testutil.Assert.assertThrows;
+import static seedu.algobase.testutil.TypicalProblems.getTypicalAlgoBase;
+
+import org.junit.jupiter.api.Test;
+
+import seedu.algobase.model.Model;
+import seedu.algobase.model.ModelManager;
+import seedu.algobase.model.UserPrefs;
+
+class HelpCommandTest {
+
+    private Model model = new ModelManager(getTypicalAlgoBase(), new UserPrefs());
+    private Model expectedModel = new ModelManager(getTypicalAlgoBase(), new UserPrefs());
+    private static final String EXPECTED_COMMAND_LIST = "Available commands are: [add, addplan, addtag, addtag, clear, delete, deleteplan, deletetag, deletetask, donetask, edit, editplan, edittag, exit, find, findplan, help, list, listplan, listtag, sort, switch, undonetask]\n" +
+        "More information can be found in the popup window.";
+
+    @Test
+    void constructor_nullCommandClassWithoutListingAllCommands_throwsNullPointerException() {
+        assertThrows(NullPointerException.class, () -> new HelpCommand(null, false));
+    }
+
+    @Test
+    void constructor_nullCommandClassWithListingAllCommands_success() {
+        HelpCommand command = new HelpCommand(null, true);
+        // Help command does nothing to the model
+        // The line below breaks for unknown reason...
+        // assertCommandSuccess(command, model, EXPECTED_COMMAND_LIST, expectedModel);
+    }
+
+    @Test
+    void execute_correctCommandWord_showsMessageUsage() {
+        HelpCommand command = new HelpCommand(AddCommand.class, false);
+        assertCommandSuccess(command, model, AddCommand.MESSAGE_USAGE, expectedModel);
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/seedu/algobase/logic/parser/CommandParserTestUtil.java b/src/test/java/seedu/algobase/logic/parser/CommandParserTestUtil.java
new file mode 100644
index 00000000000..1b055c25d2d
--- /dev/null
+++ b/src/test/java/seedu/algobase/logic/parser/CommandParserTestUtil.java
@@ -0,0 +1,38 @@
+package seedu.algobase.logic.parser;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import seedu.algobase.logic.commands.Command;
+import seedu.algobase.logic.parser.exceptions.ParseException;
+
+/**
+ * Contains helper methods for testing command parsers.
+ */
+public class CommandParserTestUtil {
+
+    /**
+     * Asserts that the parsing of {@code userInput} by {@code parser} is successful and the command created
+     * equals to {@code expectedCommand}.
+     */
+    public static void assertParseSuccess(Parser parser, String userInput, Command expectedCommand) {
+        try {
+            Command command = parser.parse(userInput);
+            assertEquals(expectedCommand, command);
+        } catch (ParseException pe) {
+            throw new IllegalArgumentException("Invalid userInput.", pe);
+        }
+    }
+
+    /**
+     * Asserts that the parsing of {@code userInput} by {@code parser} is unsuccessful and the error message
+     * equals to {@code expectedMessage}.
+     */
+    public static void assertParseFailure(Parser parser, String userInput, String expectedMessage) {
+        try {
+            parser.parse(userInput);
+            throw new AssertionError("The expected ParseException was not thrown.");
+        } catch (ParseException pe) {
+            assertEquals(expectedMessage, pe.getMessage());
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/seedu/algobase/logic/parser/HelpCommandParserTest.java b/src/test/java/seedu/algobase/logic/parser/HelpCommandParserTest.java
new file mode 100644
index 00000000000..4bc3675c06d
--- /dev/null
+++ b/src/test/java/seedu/algobase/logic/parser/HelpCommandParserTest.java
@@ -0,0 +1,37 @@
+package seedu.algobase.logic.parser;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static seedu.algobase.commons.core.Messages.MESSAGE_INVALID_COMMAND_NAME;
+import static seedu.algobase.logic.parser.CommandParserTestUtil.assertParseFailure;
+import static seedu.algobase.logic.parser.CommandParserTestUtil.assertParseSuccess;
+
+import org.junit.jupiter.api.Test;
+
+import seedu.algobase.logic.commands.AddCommand;
+import seedu.algobase.logic.commands.HelpCommand;
+import seedu.algobase.logic.parser.exceptions.ParseException;
+
+class HelpCommandParserTest {
+    private HelpCommandParser helpCommandParser = new HelpCommandParser();
+    private static final String INVALID_COMMAND_WORD = "1nval1dC0mmand";
+    private static final String VALID_COMMAND_WORD = AddCommand.COMMAND_WORD;
+    private static final Class VALID_COMMAND_CLASS = AddCommand.class;
+
+    @Test
+    void parse_emptyInput_returnsListAllHelpCommand() throws ParseException {
+        HelpCommand helpCommand = helpCommandParser.parse("");
+        assertTrue(helpCommand.isListAllCommands());
+    }
+
+    @Test
+    void parse_wrongCommandWord_throwsInvalidCommandWordException() {
+        String expectedMessage = String.format(MESSAGE_INVALID_COMMAND_NAME, INVALID_COMMAND_WORD);
+        assertParseFailure(helpCommandParser, INVALID_COMMAND_WORD, expectedMessage);
+    }
+
+    @Test
+    void parse_correctCommandWord_returnsHelpCommandForTheCommand() {
+        assertParseSuccess(helpCommandParser, VALID_COMMAND_WORD,
+            new HelpCommand(VALID_COMMAND_CLASS, false));
+    }
+}
\ No newline at end of file

From e81317a1c4250d8b514e8ff4bfc8203e09d4bc24 Mon Sep 17 00:00:00 2001
From: Tan Yuanhong <leotan.yh@gmail.com>
Date: Thu, 17 Oct 2019 15:16:42 +0800
Subject: [PATCH 5/7] Fix checkstyle errors

---
 .../algobase/logic/commands/HelpCommand.java     | 16 ++++++++--------
 .../algobase/logic/commands/HelpCommandTest.java |  8 +++++---
 .../logic/parser/CommandParserTestUtil.java      |  2 +-
 .../logic/parser/HelpCommandParserTest.java      |  4 ++--
 4 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/src/main/java/seedu/algobase/logic/commands/HelpCommand.java b/src/main/java/seedu/algobase/logic/commands/HelpCommand.java
index aa6d3293967..9c33ee6c09e 100644
--- a/src/main/java/seedu/algobase/logic/commands/HelpCommand.java
+++ b/src/main/java/seedu/algobase/logic/commands/HelpCommand.java
@@ -23,14 +23,6 @@ public class HelpCommand extends Command {
     private final boolean isListAllCommands;
     private final Class commandClass;
 
-    public boolean isListAllCommands() {
-        return isListAllCommands;
-    }
-
-    public Class getCommandClass() {
-        return commandClass;
-    }
-
     public HelpCommand(Class commandClass, boolean isListAllCommands) {
         this.isListAllCommands = isListAllCommands;
         if (!isListAllCommands) {
@@ -41,6 +33,14 @@ public HelpCommand(Class commandClass, boolean isListAllCommands) {
         }
     }
 
+    public boolean isListAllCommands() {
+        return isListAllCommands;
+    }
+
+    public Class getCommandClass() {
+        return commandClass;
+    }
+
     @Override
     public CommandResult execute(Model model) {
         if (isListAllCommands) {
diff --git a/src/test/java/seedu/algobase/logic/commands/HelpCommandTest.java b/src/test/java/seedu/algobase/logic/commands/HelpCommandTest.java
index eb24dcc84c9..0e936f417cb 100644
--- a/src/test/java/seedu/algobase/logic/commands/HelpCommandTest.java
+++ b/src/test/java/seedu/algobase/logic/commands/HelpCommandTest.java
@@ -12,10 +12,12 @@
 
 class HelpCommandTest {
 
+    private static final String EXPECTED_COMMAND_LIST = "Available commands are: [add, addplan, addtag, "
+        + "addtag, clear, delete, deleteplan, deletetag, deletetask, donetask, edit, editplan, edittag, exit, "
+        + "find, findplan, help, list, listplan, listtag, sort, switch, undonetask]\n"
+        + "More information can be found in the popup window.";
     private Model model = new ModelManager(getTypicalAlgoBase(), new UserPrefs());
     private Model expectedModel = new ModelManager(getTypicalAlgoBase(), new UserPrefs());
-    private static final String EXPECTED_COMMAND_LIST = "Available commands are: [add, addplan, addtag, addtag, clear, delete, deleteplan, deletetag, deletetask, donetask, edit, editplan, edittag, exit, find, findplan, help, list, listplan, listtag, sort, switch, undonetask]\n" +
-        "More information can be found in the popup window.";
 
     @Test
     void constructor_nullCommandClassWithoutListingAllCommands_throwsNullPointerException() {
@@ -35,4 +37,4 @@ void execute_correctCommandWord_showsMessageUsage() {
         HelpCommand command = new HelpCommand(AddCommand.class, false);
         assertCommandSuccess(command, model, AddCommand.MESSAGE_USAGE, expectedModel);
     }
-}
\ No newline at end of file
+}
diff --git a/src/test/java/seedu/algobase/logic/parser/CommandParserTestUtil.java b/src/test/java/seedu/algobase/logic/parser/CommandParserTestUtil.java
index 1b055c25d2d..c49d2eb7630 100644
--- a/src/test/java/seedu/algobase/logic/parser/CommandParserTestUtil.java
+++ b/src/test/java/seedu/algobase/logic/parser/CommandParserTestUtil.java
@@ -35,4 +35,4 @@ public static void assertParseFailure(Parser parser, String userInput, String ex
             assertEquals(expectedMessage, pe.getMessage());
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/test/java/seedu/algobase/logic/parser/HelpCommandParserTest.java b/src/test/java/seedu/algobase/logic/parser/HelpCommandParserTest.java
index 4bc3675c06d..28a07cb0544 100644
--- a/src/test/java/seedu/algobase/logic/parser/HelpCommandParserTest.java
+++ b/src/test/java/seedu/algobase/logic/parser/HelpCommandParserTest.java
@@ -12,10 +12,10 @@
 import seedu.algobase.logic.parser.exceptions.ParseException;
 
 class HelpCommandParserTest {
-    private HelpCommandParser helpCommandParser = new HelpCommandParser();
     private static final String INVALID_COMMAND_WORD = "1nval1dC0mmand";
     private static final String VALID_COMMAND_WORD = AddCommand.COMMAND_WORD;
     private static final Class VALID_COMMAND_CLASS = AddCommand.class;
+    private HelpCommandParser helpCommandParser = new HelpCommandParser();
 
     @Test
     void parse_emptyInput_returnsListAllHelpCommand() throws ParseException {
@@ -34,4 +34,4 @@ void parse_correctCommandWord_returnsHelpCommandForTheCommand() {
         assertParseSuccess(helpCommandParser, VALID_COMMAND_WORD,
             new HelpCommand(VALID_COMMAND_CLASS, false));
     }
-}
\ No newline at end of file
+}

From 947ecfd0a2e2acb25bf9d425a1d8df9462837362 Mon Sep 17 00:00:00 2001
From: Tan Yuanhong <leotan.yh@gmail.com>
Date: Thu, 17 Oct 2019 15:22:56 +0800
Subject: [PATCH 6/7] Update UG for help command

---
 docs/UserGuide.adoc | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/docs/UserGuide.adoc b/docs/UserGuide.adoc
index 8513e208db6..b37ba19c543 100644
--- a/docs/UserGuide.adoc
+++ b/docs/UserGuide.adoc
@@ -30,7 +30,7 @@ AlgoBase (AB) is for those who prefer to use a desktop app for managing algorith
 image::Ui.png[width="790"]
 +
 .  Type the command in the command box and press kbd:[Enter] to execute it. +
-e.g. typing *`help`* and pressing kbd:[Enter] will open the help window.
+e.g. typing *`help`* and pressing kbd:[Enter] will list all possible commands in the result window and open the help window.
 .  Some example commands you can try:
 
 * *`list`* : lists all problems
@@ -297,7 +297,13 @@ Switches to the tab at index 1.
 
 ==== Viewing help : `help`
 
-Format: `help`
+List all possible commands or find command usage using the command word. +
+Format: `help [COMMAND_WORD]`
+
+* `help`
+Shows all possible commands.
+* `help add`
+Shows command usage for `add` command.
 
 ==== Clearing all entries : `clear`
 

From 90f79a8d79ecacec1690b264211946b29280ac1c Mon Sep 17 00:00:00 2001
From: Tan Yuanhong <leotan.yh@gmail.com>
Date: Fri, 18 Oct 2019 12:32:22 +0800
Subject: [PATCH 7/7] Fix typos and test bug

---
 src/main/java/seedu/algobase/logic/commands/Command.java   | 1 -
 .../java/seedu/algobase/logic/commands/HelpCommand.java    | 3 +--
 .../seedu/algobase/logic/commands/HelpCommandTest.java     | 7 +++----
 3 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/src/main/java/seedu/algobase/logic/commands/Command.java b/src/main/java/seedu/algobase/logic/commands/Command.java
index 6e121cc039b..e752d76ad23 100644
--- a/src/main/java/seedu/algobase/logic/commands/Command.java
+++ b/src/main/java/seedu/algobase/logic/commands/Command.java
@@ -12,7 +12,6 @@ public abstract class Command {
         AddCommand.class,
         AddPlanCommand.class,
         AddTagCommand.class,
-        AddTagCommand.class,
         ClearCommand.class,
         DeleteCommand.class,
         DeletePlanCommand.class,
diff --git a/src/main/java/seedu/algobase/logic/commands/HelpCommand.java b/src/main/java/seedu/algobase/logic/commands/HelpCommand.java
index 9c33ee6c09e..32359a8ef07 100644
--- a/src/main/java/seedu/algobase/logic/commands/HelpCommand.java
+++ b/src/main/java/seedu/algobase/logic/commands/HelpCommand.java
@@ -18,7 +18,7 @@ public class HelpCommand extends Command {
         + ": Shows program usage instructions.\n"
         + "Parameter:\n"
         + "COMMAND_NAME (can be empty if you want a list of possible commands)\n"
-        + "Example: " + COMMAND_WORD + "find";
+        + "Example: " + COMMAND_WORD + " find";
 
     private final boolean isListAllCommands;
     private final Class commandClass;
@@ -50,7 +50,6 @@ public CommandResult execute(Model model) {
             }
             String commandPrompt = "Available commands are: " + commandWords.toString() + "\n"
                 + "More information can be found in the popup window.";
-            System.out.println(commandPrompt);
             return new CommandResult(commandPrompt, true, false);
         } else {
             String commandUsage = getClassStringField(commandClass, "MESSAGE_USAGE");
diff --git a/src/test/java/seedu/algobase/logic/commands/HelpCommandTest.java b/src/test/java/seedu/algobase/logic/commands/HelpCommandTest.java
index 0e936f417cb..724a52e4ec1 100644
--- a/src/test/java/seedu/algobase/logic/commands/HelpCommandTest.java
+++ b/src/test/java/seedu/algobase/logic/commands/HelpCommandTest.java
@@ -13,7 +13,7 @@
 class HelpCommandTest {
 
     private static final String EXPECTED_COMMAND_LIST = "Available commands are: [add, addplan, addtag, "
-        + "addtag, clear, delete, deleteplan, deletetag, deletetask, donetask, edit, editplan, edittag, exit, "
+        + "clear, delete, deleteplan, deletetag, deletetask, donetask, edit, editplan, edittag, exit, "
         + "find, findplan, help, list, listplan, listtag, sort, switch, undonetask]\n"
         + "More information can be found in the popup window.";
     private Model model = new ModelManager(getTypicalAlgoBase(), new UserPrefs());
@@ -27,9 +27,8 @@ void constructor_nullCommandClassWithoutListingAllCommands_throwsNullPointerExce
     @Test
     void constructor_nullCommandClassWithListingAllCommands_success() {
         HelpCommand command = new HelpCommand(null, true);
-        // Help command does nothing to the model
-        // The line below breaks for unknown reason...
-        // assertCommandSuccess(command, model, EXPECTED_COMMAND_LIST, expectedModel);
+        assertCommandSuccess(command, model,
+            new CommandResult(EXPECTED_COMMAND_LIST, true, false), expectedModel);
     }
 
     @Test