diff --git a/src/api/chat_completions.rs b/src/api/chat_completions.rs
index 30a5974..a78df05 100644
--- a/src/api/chat_completions.rs
+++ b/src/api/chat_completions.rs
@@ -78,7 +78,9 @@ impl Instance {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::read_words_from_file;
     use httpmock::prelude::*;
+    use std::path::PathBuf;
 
     #[tokio::test]
     async fn test_post_chat_completions() {
@@ -104,4 +106,39 @@ mod tests {
             .unwrap();
         mock.assert();
     }
+
+    #[test]
+    fn test_build_request_body() {
+        // Mock input data
+        let link_words = vec!["link1".to_string(), "link2".to_string()];
+        let avoid_words = vec!["avoid1".to_string(), "avoid2".to_string()];
+        let model_id = "model".to_string();
+
+        // Assign result to the result of build_request_body() method
+        let result = Instance::build_request_body(&link_words, &avoid_words, &model_id);
+
+        // Format expected content
+        let expected_content = format!(
+            "To Link:\n{}\n\nTo Avoid:\n{}",
+            link_words.join("\n"),
+            avoid_words.join("\n")
+        );
+
+        // Mock expected output
+        let expected = json!(
+            {
+            "messages": [
+                {
+                    "role": "system",
+                    "content": SYSTEM_PROMPT,
+                },
+                {
+                    "role": "user",
+                    "content": expected_content
+                }
+            ],
+            "model": model_id
+        });
+        assert_eq!(expected, result);
+    }
 }