diff --git a/src/main/java/seedu/address/logic/parser/EditCommandParser.java b/src/main/java/seedu/address/logic/parser/EditCommandParser.java
index 6332eec05bf..517f1b5e671 100644
--- a/src/main/java/seedu/address/logic/parser/EditCommandParser.java
+++ b/src/main/java/seedu/address/logic/parser/EditCommandParser.java
@@ -57,7 +57,6 @@ public EditCommand parse(String args) throws ParseException {
         if (argMultimap.getValue(PREFIX_DIFFICULTY).isPresent()) {
             editAnswerableDescriptor.setDifficulty(ParserUtil.parseDifficulty(argMultimap.getValue(PREFIX_DIFFICULTY).get()));
         }
-     
 
         parseCategoriesForEdit(argMultimap.getAllValues(PREFIX_CATEGORY)).ifPresent(editAnswerableDescriptor::setCategories);
 
@@ -79,8 +78,7 @@ private Optional<Set<Category>> parseCategoriesForEdit(Collection<String> catego
         if (categories.isEmpty()) {
             return Optional.empty();
         }
-        Collection<String> categorySet = categories.size() == 1 && categories.contains("") ? Collections.emptySet() : categories;
-        return Optional.of(ParserUtil.parseCategories(categorySet));
+        return Optional.of(ParserUtil.parseCategories(categories));
     }
 
 }
diff --git a/src/main/java/seedu/address/model/category/Category.java b/src/main/java/seedu/address/model/category/Category.java
index 7c1edf6d986..9029b26da28 100644
--- a/src/main/java/seedu/address/model/category/Category.java
+++ b/src/main/java/seedu/address/model/category/Category.java
@@ -11,7 +11,6 @@ public class Category {
 
     public static final String MESSAGE_CONSTRAINTS = "Category names should not be blank";
     public static final String VALIDATION_REGEX = "^(?=\\s*\\S).*$";
-//    public static final String VALIDATION_REGEX = ".*";
 
     public final String categoryName;
 
diff --git a/src/main/java/seedu/address/storage/JsonAdaptedAnswerable.java b/src/main/java/seedu/address/storage/JsonAdaptedAnswerable.java
index 61d4dfc2b39..46a922b030d 100644
--- a/src/main/java/seedu/address/storage/JsonAdaptedAnswerable.java
+++ b/src/main/java/seedu/address/storage/JsonAdaptedAnswerable.java
@@ -62,7 +62,7 @@ public JsonAdaptedAnswerable(Answerable source) {
         correctAnswerSet.addAll(source.getCorrectAnswerSet().stream()
                 .map(JsonAdaptedAnswer::new)
                 .collect(Collectors.toList()));
-        wrongAnswerSet.addAll(source.getCorrectAnswerSet().stream()
+        wrongAnswerSet.addAll(source.getWrongAnswerSet().stream()
                 .map(JsonAdaptedAnswer::new)
                 .collect(Collectors.toList()));
         categories.addAll(source.getCategories().stream()
diff --git a/src/test/java/seedu/address/logic/commands/CommandTestUtil.java b/src/test/java/seedu/address/logic/commands/CommandTestUtil.java
index 08123c9d19e..708bad99859 100644
--- a/src/test/java/seedu/address/logic/commands/CommandTestUtil.java
+++ b/src/test/java/seedu/address/logic/commands/CommandTestUtil.java
@@ -51,7 +51,7 @@ public class CommandTestUtil {
     public static final String CATEGORY_DESC_UML = " " + PREFIX_CATEGORY + VALID_CATEGORY_UML;
     public static final String CATEGORY_DESC_GREENFIELD = " " + PREFIX_CATEGORY + VALID_CATEGORY_GREENFIELD;
 
-    public static final String INVALID_QUESTION_DESC = " " + PREFIX_QUESTION + " "; // empty string not allowed for questions
+    public static final String INVALID_QUESTION_DESC = " " + PREFIX_QUESTION + ""; // empty string not allowed for questions
     public static final String INVALID_DIFFICULTY_DESC = " " + PREFIX_DIFFICULTY + "911a"; // 'a' not allowed in difficulty
     public static final String INVALID_CATEGORY_DESC = " " + PREFIX_CATEGORY + ""; // category cannot just be whitespace
 
diff --git a/src/test/java/seedu/address/logic/parser/EditCommandParserTest.java b/src/test/java/seedu/address/logic/parser/EditCommandParserTest.java
index 9ca23056202..4a1e4cf52c3 100644
--- a/src/test/java/seedu/address/logic/parser/EditCommandParserTest.java
+++ b/src/test/java/seedu/address/logic/parser/EditCommandParserTest.java
@@ -171,14 +171,4 @@ public void parse_invalidValueFollowedByValidValue_success() {
         assertParseSuccess(parser, userInput, expectedCommand);
     }
 
-    @Test
-    public void parse_resetTags_success() {
-        Index targetIndex = INDEX_THIRD_ANSWERABLE;
-        String userInput = targetIndex.getOneBased() + CATEGORY_EMPTY;
-
-        EditAnswerableDescriptor descriptor = new EditAnswerableDescriptorBuilder().withCategories().build();
-        EditCommand expectedCommand = new EditCommand(targetIndex, descriptor);
-
-        assertParseSuccess(parser, userInput, expectedCommand);
-    }
 }
diff --git a/src/test/java/seedu/address/storage/JsonAdaptedAnswerableTest.java b/src/test/java/seedu/address/storage/JsonAdaptedAnswerableTest.java
index 846af6f6b7d..b8d1111e67a 100644
--- a/src/test/java/seedu/address/storage/JsonAdaptedAnswerableTest.java
+++ b/src/test/java/seedu/address/storage/JsonAdaptedAnswerableTest.java
@@ -34,8 +34,8 @@ public class JsonAdaptedAnswerableTest {
 
     @Test
     public void toModelType_validPersonDetails_returnsPerson() throws Exception {
-        JsonAdaptedAnswerable person = new JsonAdaptedAnswerable(B_ANSWERABLE);
-        assertEquals(B_ANSWERABLE, person.toModelType());
+        JsonAdaptedAnswerable answerable = new JsonAdaptedAnswerable(B_ANSWERABLE);
+        assertEquals(B_ANSWERABLE, answerable.toModelType());
     }
 
     @Test