test: added basic extract json tests for terminal tool

Author: ErikBjare

tests/test_tools_subagent.py

@@ -0,0 +1,28 @@
+import json
+
+from gptme.tools.subagent import _extract_json
+
+
+def test_extract_json_block():
+    s = """
+Here is a result:
+```json
+{ "status": "ok" }
+```
+"""
+    assert _extract_json(s) == '{ "status": "ok" }'
+
+
+def test_extract_json_raw():
+    s = """
+{
+  "result": "The 49th Fibonacci number is 7778742049.",
+  "status": "success"
+}
+"""
+    assert json.loads(_extract_json(s)) == json.loads(s)
+
+
+def test_extract_json_empty():
+    s = ""
+    assert _extract_json(s) == ""