feat: Implement filter_tags function with comprehensive unit tests

src/tag_engine.rs

@@ -92,6 +92,12 @@ pub fn parse_tags(filename: &str) -> Result<(String, Vec<String>, String), Parse
     Ok((base_name, tags, extension))
 }
 
+pub fn filter_tags(current: Vec<String>, remove: &[String]) -> Vec<String> {
+    current.into_iter()
+        .filter(|tag| !remove.contains(tag))
+        .collect()
+}
+
 pub fn add_tags(current: Vec<String>, new: Vec<String>) -> Vec<String> {
     let mut result = current;
     
@@ -257,4 +263,28 @@ mod tests {
         assert_eq!(tags, vec!["tag1"]);
         assert_eq!(ext, ".txt");
     }
+
+    #[test]
+    fn test_filter_tags_multi_remove() {
+        let current = vec!["tag1".to_string(), "tag2".to_string(), "tag3".to_string()];
+        let remove = vec!["tag1".to_string(), "tag3".to_string()];
+        let result = filter_tags(current, &remove);
+        assert_eq!(result, vec!["tag2"]);
+    }
+
+    #[test]
+    fn test_filter_tags_non_existent() {
+        let current = vec!["tag1".to_string(), "tag2".to_string()];
+        let remove = vec!["tag3".to_string()];
+        let result = filter_tags(current, &remove);
+        assert_eq!(result, vec!["tag1", "tag2"]);
+    }
+
+    #[test]
+    fn test_filter_tags_empty_result() {
+        let current = vec!["tag1".to_string(), "tag2".to_string()];
+        let remove = vec!["tag1".to_string(), "tag2".to_string()];
+        let result = filter_tags(current, &remove);
+        assert!(result.is_empty());
+    }
 }