Add test and update readme

README.md

@@ -439,6 +439,22 @@ Returns the tracer-flares in the following json format:
 
 If there was an error parsing the tracer-flare form, that will be recorded under `error`.
 
+### /test/settings (POST)
+
+Allows to change some settings on the fly.
+This endpoint takes a POST request with a json content listing the keys and values to apply.
+
+```json
+{ 'key': value }
+```
+
+Supported keys:
+ - `trace_request_delay`: sets a delay to apply to trace and telemetry requests
+
+ ```
+curl -X POST 'http://0.0.0.0:8126/test/settings' -d '{ "trace_request_delay": 5 }'
+```
+
 ## Development
 
 ### Prerequisites

ddapm_test_agent/agent.py

@@ -669,7 +669,7 @@ async def handle_settings(self, request: Request) -> web.Response:
         # First pass to validate the data
         for key in data:
             if key not in request.app:
-                return web.HTTPUnprocessableEntity(text=f"Unknown key: {key}")
+                return web.HTTPUnprocessableEntity(text=f"Unknown key: '{key}'")
 
         # Second pass to apply the config
         for key in data:

tests/test_agent.py

@@ -400,3 +400,37 @@ def test_uds(tmp_path, available_port):
         pass
     else:
         raise Exception("Test agent failed to start")
+
+
+async def test_post_known_settings(
+        agent
+):
+    resp = await agent.post(
+        "/test/settings",
+        data='{ "trace_request_delay": 5 }',
+    )
+
+    assert resp.status == 202, await resp.text()
+    assert agent.app["trace_request_delay"] == 5
+
+    resp = await agent.post(
+        "/test/settings",
+        data='{ "trace_request_delay": 0 }',
+    )
+
+    assert resp.status == 202, await resp.text()
+    assert agent.app["trace_request_delay"] == 0
+
+
+async def test_post_unknown_settings(
+        agent,
+):
+    resp = await agent.post(
+        "/test/settings",
+        data='{ "dummy_setting": 5 }',
+    )
+
+    assert resp.status == 422
+    text = await resp.text()
+    assert text == "Unknown key: 'dummy_setting'"
+    assert 'dummy_setting' not in agent.app