fix(amazonq): Truncating user prompt for unit test generation. (aws#5359)

* Adding truncation logic to testGen user prompt

Author: laileni-aws

.changes/next-release/bugfix-47911d01-4571-42a5-b447-d443910e8aee.json

@@ -0,0 +1,4 @@
+{
+  "type" : "bugfix",
+  "description" : "Amazon Q /test: Truncating user input to 4096 characters for unit test generation."
+}

plugins/amazonq/chat/jetbrains-community/src/software/aws/toolkits/jetbrains/services/amazonqCodeTest/controller/CodeTestChatController.kt

@@ -201,12 +201,11 @@ class CodeTestChatController(
 
             session.isCodeBlockSelected = selectionRange !== null
 
-            // This check is added to remove /test if user accidentally added while doing Regenerate unit tests.
-            val userPrompt = if (message.prompt.startsWith("/test")) {
-                message.prompt.substringAfter("/test ").trim()
-            } else {
-                message.prompt
-            }
+            // This removes /test if user accidentally added while doing Regenerate unit tests and truncates the user response to 4096 characters.
+            val userPrompt = message.prompt
+                .let { if (it.startsWith("/test")) it.substringAfter("/test ").trim() else it }
+                .take(4096)
+
             CodeWhispererUTGChatManager.getInstance(project).generateTests(userPrompt, codeTestChatHelper, null, selectionRange)
         } else {
             // Not adding a progress bar to unsupported language cases