fix(backend): add @Builder.Default to entity fields and add unit test suite

backend/src/main/java/com/rit/portal/entity/CommunityAnswer.java

@@ -30,11 +30,14 @@ public class CommunityAnswer {
     private String author;
 
     @Column(name = "upvotes")
+    @Builder.Default
     private Integer upvotes = 0;
 
     @Column(name = "is_accepted")
+    @Builder.Default
     private Boolean isAccepted = false;
 
     @Column(name = "created_at")
+    @Builder.Default
     private LocalDateTime createdAt = LocalDateTime.now();
 }

backend/src/main/java/com/rit/portal/entity/CommunityQuestion.java

@@ -29,15 +29,19 @@ public class CommunityQuestion {
     private String author;
 
     @Column(name = "upvotes")
+    @Builder.Default
     private Integer upvotes = 0;
 
     @Column(name = "tags", columnDefinition = "text[]")
+    @Builder.Default
     private List<String> tags = new ArrayList<>();
 
     @Column(name = "is_answered")
+    @Builder.Default
     private Boolean isAnswered = false;
 
     @Column(name = "created_at")
+    @Builder.Default
     private LocalDateTime createdAt = LocalDateTime.now();
 
     @OneToMany(mappedBy = "question", cascade = CascadeType.ALL, fetch = FetchType.EAGER)

backend/src/main/java/com/rit/portal/entity/NotePyq.java

@@ -39,8 +39,10 @@ public class NotePyq {
     private String fileSize;
 
     @Column(name = "downloads_count")
+    @Builder.Default
     private Integer downloadsCount = 0;
 
     @Column(name = "uploaded_at")
+    @Builder.Default
     private LocalDateTime uploadedAt = LocalDateTime.now();
 }