Add unit tests

tests/test_slo_tracker.py

@@ -0,0 +1,20 @@
+from unittest.mock import MagicMock, patch
+from slo_tracker import evaluate_slo
+
+
+def make_prom(value):
+    prom = MagicMock()
+    prom.custom_query.return_value = [{"value": [0, str(value)]}]
+    return prom
+
+
+def test_slo_ok():
+    slo = {"name": "test", "query": "up", "target": 0.99}
+    result = evaluate_slo(make_prom(0.999), slo, "7d")
+    assert result["ok"] is True
+
+
+def test_slo_burning():
+    slo = {"name": "test", "query": "up", "target": 0.99}
+    result = evaluate_slo(make_prom(0.985), slo, "7d")
+    assert result["ok"] is False