feat(shared): add health checks and Prometheus metrics

1 files changed, 88 insertions, 0 deletions

diff --git a/shared/tests/test_healthcheck.py b/shared/tests/test_healthcheck.py
new file mode 100644
index 0000000..1af86b1
--- /dev/null
+++ b/shared/tests/test_healthcheck.py
@@ -0,0 +1,88 @@
+"""Tests for health check server."""
+import pytest
+import asyncio
+from prometheus_client import CollectorRegistry
+
+
+@pytest.fixture
+def registry():
+    return CollectorRegistry()
+
+
+def make_server(service_name="test-service", port=8080, registry=None):
+    from shared.healthcheck import HealthCheckServer
+    return HealthCheckServer(service_name, port=port, registry=registry)
+
+
+def test_init_defaults(registry):
+    """HealthCheckServer initialises with service name and port."""
+    server = make_server("my-service", registry=registry)
+    assert server.service_name == "my-service"
+    assert server.port == 8080
+    assert server._checks == {}
+
+
+def test_register_check(registry):
+    """register_check stores an async callable."""
+    server = make_server(registry=registry)
+
+    async def check_redis():
+        return True
+
+    server.register_check("redis", check_redis)
+    assert "redis" in server._checks
+    assert server._checks["redis"] is check_redis
+
+
+@pytest.mark.asyncio
+async def test_run_checks_all_pass(registry):
+    """run_checks returns 'ok' when all checks pass."""
+    server = make_server(registry=registry)
+
+    async def ok_check():
+        return True
+
+    server.register_check("db", ok_check)
+    server.register_check("redis", ok_check)
+
+    result = await server.run_checks()
+    assert result["status"] == "ok"
+    assert result["service"] == "test-service"
+    assert "uptime_seconds" in result
+    assert result["checks"]["db"] == "ok"
+    assert result["checks"]["redis"] == "ok"
+
+
+@pytest.mark.asyncio
+async def test_run_checks_one_fails(registry):
+    """run_checks returns 'degraded' when a check fails."""
+    server = make_server(registry=registry)
+
+    async def ok_check():
+        return True
+
+    async def bad_check():
+        raise ConnectionError("down")
+
+    server.register_check("db", ok_check)
+    server.register_check("redis", bad_check)
+
+    result = await server.run_checks()
+    assert result["status"] == "degraded"
+    assert result["checks"]["db"] == "ok"
+    assert "fail" in result["checks"]["redis"]
+
+
+@pytest.mark.asyncio
+async def test_run_checks_false_is_fail(registry):
+    """run_checks treats False return as failure."""
+    server = make_server(registry=registry)
+
+    async def false_check():
+        return False
+
+    server.register_check("cache", false_check)
+
+    result = await server.run_checks()
+    assert result["status"] == "degraded"
+    assert result["checks"]["cache"] == "fail"