ISSUE-7711: Add GET - api/../groups/test_results endpoint documentation

RESTful-API.md

@@ -1170,6 +1170,74 @@ NOTE: The request body is validated against a schema and must not exceed 10MB in
 
 NOTE: Authentication is required via API key. The authenticated user's role is used as the creator of the test run.
 
+### GET /api/courses/:course_id/assignments/:assignment_id/groups/:id/test_results
+
+- description: Get automated test results for the given group for the given assignment. Supports two response formats:
+    1. **Default**: Returns only the latest test run, grouped by test group name. Matches the UI download format.
+    2. **Metadata Format** (with `include_metadata=true`): Returns all test runs with full metadata and timing information.
+- optional parameters:
+    - `include_metadata` (boolean): Set to `true` to return full test run history. Defaults to `false`.
+- supported content types: `application/json`, `application/xml`
+- example response (default format, json):
+
+```json
+{
+  "Test Group 1": [
+    {
+      "name": "Test Group 1",
+      "test_groups_id": 7,
+      "group_name": "group1",
+      "test_result_name": "test_addition",
+      "status": "pass",
+      "marks_earned": 3.0,
+      "marks_total": 5.0,
+      "output": "All test cases passed",
+      "extra_info": null,
+      "error_type": null
+    }
+  ]
+}
+```
+
+- example response (metadata format with `include_metadata=true`, json):
+
+```json
+[
+  {
+    "id": 42,
+    "status": "complete",
+    "created_at": "2025-12-03T11:38:59.569-05:00",
+    "problems": null,
+    "test_groups": [
+      {
+        "name": "Test Group 1",
+        "marks_earned": 5.0,
+        "marks_total": 10.0,
+        "time": 1250,
+        "tests": [
+          {
+            "name": "test_addition",
+            "status": "pass",
+            "marks_earned": 3.0,
+            "marks_total": 5.0,
+            "output": "All test cases passed",
+            "time": 125
+          }
+        ]
+      }
+    ]
+  }
+]
+```
+
+NOTE: The default format is consistent with the assignment test results download available through the UI.
+
+NOTE: The metadata format returns all test runs ordered by creation date (newest first) and includes timing data.
+
+NOTE: Both formats support XML responses by setting the `Accept` header to `application/xml`.
+
+NOTE: Returns 404 if the group has no test results.
+
 ### POST /api/courses/:course_id/assignments/:assignment_id/groups/:group_id/extension
 
 - description: Create an extension for the given group for the given assignment