Refactor JUnit tests

The JUnit tests could be better structured.

This needs to change to ensure that the tests are clear and
maintainable.

Let's refactor the JUnit tests.

This enhances test-code readability and maintainability.

src/test/java/moimoi/util/command/AddCommandTest.java

@@ -158,24 +158,4 @@ public void execute_invalidPeriod_invalidPeriodExceptionThrown() {
         }
     }
 
-    @Test
-    public void execute_validInputs_success() throws Exception {
-
-        AddCommand addCommand;
-
-        addCommand = new AddCommand(CommandEnum.DEADLINE, "dummy /by 2024-08-22 18:00");
-        addCommand.execute(this.storage, this.tasks);
-
-        addCommand = new AddCommand(CommandEnum.EVENT,
-                    "dummy /from 2024-08-22 18:00 /to 2024-08-22 18:30");
-        addCommand.execute(this.storage, this.tasks);
-
-        addCommand = new AddCommand(CommandEnum.PERIOD, "dummy /for 17");
-        addCommand.execute(this.storage, this.tasks);
-
-        addCommand = new AddCommand(CommandEnum.PERIOD, "dummy /for 17.5");
-        addCommand.execute(this.storage, this.tasks);
-
-    }
-
 }

src/test/java/moimoi/util/command/DeleteTest.java

@@ -75,11 +75,4 @@ public void execute_invalidIndex_invalidIndexExceptionThrown() {
 
     }
 
-    @Test
-    public void execute_validIndex_success() throws Exception {
-        this.tasks.add(this.task);
-        DeleteCommand deleteCommand = new DeleteCommand("1");
-        deleteCommand.execute(this.storage, this.tasks);
-    }
-
 }

src/test/java/moimoi/util/command/MarkCommandTest.java

@@ -75,11 +75,4 @@ public void execute_invalidIndex_invalidIndexExceptionThrown() {
 
     }
 
-    @Test
-    public void execute_validIndex_success() throws Exception {
-        this.tasks.add(this.task);
-        MarkCommand markCommand = new MarkCommand("1");
-        markCommand.execute(this.storage, this.tasks);
-    }
-
 }

src/test/java/moimoi/util/command/UnmarkCommandTest.java

@@ -75,11 +75,4 @@ public void execute_invalidIndex_invalidIndexExceptionThrown() {
 
     }
 
-    @Test
-    public void execute_validIndex_success() throws Exception {
-        this.tasks.add(this.task);
-        UnmarkCommand unmarkCommand = new UnmarkCommand("1");
-        unmarkCommand.execute(this.storage, this.tasks);
-    }
-
 }