Dashboard minor refactor and first unit tests (#8705)

python/ray/dashboard/tests/conftest.py

@@ -0,0 +1 @@
+from ray.tests.conftest import *  # noqa

python/ray/dashboard/tests/test_node_stats.py

@@ -0,0 +1,32 @@
+from ray.dashboard.node_stats import NodeStats
+from ray.ray_constants import REDIS_DEFAULT_PASSWORD
+from datetime import datetime
+from time import sleep
+import pytest
+
+
+def test_basic(ray_start_with_dashboard):
+    """Dashboard test that starts a Ray cluster with a dashboard server running,
+    then hits the dashboard API and asserts that it receives sensible data."""
+    redis_address = ray_start_with_dashboard["redis_address"]
+    redis_password = REDIS_DEFAULT_PASSWORD
+    node_stats = NodeStats(redis_address, redis_password)
+    node_stats.start()
+    # Wait for node stats to fire up.
+    MAX_START_TIME_S = 30
+    t_start = datetime.now()
+    while True:
+        try:
+            stats = node_stats.get_node_stats()
+            client_stats = stats and stats.get("clients")
+            if not client_stats:
+                sleep(3)
+                if (datetime.now() - t_start).seconds > MAX_START_TIME_S:
+                    pytest.fail("Node stats took too long to start up")
+                continue
+            break
+        except Exception:
+            continue
+    assert len(client_stats) == 1
+    client = client_stats[0]
+    assert len(client["workers"]) == 1