test: add policy SQL tests and a CI workflow

.github/workflows/tests.yml

@@ -0,0 +1,22 @@
+name: Tests
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.13'
+
+      - name: Install uv
+        run: python -m pip install --upgrade pip uv
+
+      - name: Run tests
+        run: uv run pytest

pyproject.toml

@@ -31,3 +31,11 @@ cloudcost = "cloudcost.cli:app"
 [build-system]
 requires = ["uv_build>=0.12.17,<0.13.0"]
 build-backend = "uv_build"
+
+[dependency-groups]
+dev = [
+    "pytest>=8.0",
+]
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]

tests/policies/test_aks_idle_nodepool.py

@@ -0,0 +1,118 @@
+from pathlib import Path
+
+import duckdb
+import pyarrow as pa
+
+from cloudcost.config.loader import PolicyConfig
+from cloudcost.policies.models import Finding
+from cloudcost.policies.runner import PolicyRunner
+
+POLICY_FILE = Path(__file__).resolve().parents[2] / "policies" / "aks_idle_nodepool.sql"
+
+
+def make_nodepools(rows: list[dict]) -> pa.Table:
+    return pa.table(
+        {
+            "resource_id": pa.array([r["resource_id"] for r in rows], type=pa.string()),
+            "resource_name": pa.array([r["resource_name"] for r in rows], type=pa.string()),
+            "vm_size": pa.array([r["vm_size"] for r in rows], type=pa.string()),
+            "node_count": pa.array([r["node_count"] for r in rows], type=pa.int64()),
+            "avg_cpu_percent": pa.array([r["avg_cpu_percent"] for r in rows], type=pa.float64()),
+            "hourly_price_per_node": pa.array(
+                [r["hourly_price_per_node"] for r in rows], type=pa.float64()
+            ),
+            "lookback_days": pa.array([r["lookback_days"] for r in rows], type=pa.int64()),
+        }
+    )
+
+
+def nodepool(**overrides) -> dict:
+    row = {
+        "resource_id": "/subscriptions/s/resourcegroups/rg/providers/vmss/pool1",
+        "resource_name": "cluster1/pool1",
+        "vm_size": "Standard_D2s_v3",
+        "node_count": 3,
+        "avg_cpu_percent": 4.0,
+        "hourly_price_per_node": 0.10,
+        "lookback_days": 7,
+    }
+    row.update(overrides)
+    return row
+
+
+def run_policy(tmp_path: Path, rows: list[dict], policy_file: Path = POLICY_FILE) -> list[Finding]:
+    db_path = tmp_path / "costs.duckdb"
+    conn = duckdb.connect(str(db_path))
+    try:
+        conn.register("nodepools", make_nodepools(rows))
+        conn.execute("CREATE TABLE fact_aks_idle_nodepool AS SELECT * FROM nodepools")
+    finally:
+        conn.close()
+
+    policy = PolicyConfig(
+        name="aks-idle-nodepool",
+        type="sql",
+        query_file=str(policy_file),
+        severity="medium",
+    )
+    return PolicyRunner(str(db_path)).run_policy(policy)
+
+
+def test_flags_nodepool_below_cpu_threshold(tmp_path: Path) -> None:
+    findings = run_policy(tmp_path, [nodepool()])
+
+    assert len(findings) == 1
+    finding = findings[0]
+    assert finding.provider == "azure"
+    assert finding.service_name == "AKS Node Pool"
+    assert finding.severity == "medium"
+    assert finding.resource_id == "/subscriptions/s/resourcegroups/rg/providers/vmss/pool1"
+    assert finding.evidence["evidence_reason"] == (
+        "3 x Standard_D2s_v3 nodes averaging 4.0% CPU over 7 days"
+    )
+
+
+def test_monthly_cost_is_nodes_times_hourly_price_times_730(tmp_path: Path) -> None:
+    findings = run_policy(tmp_path, [nodepool(node_count=3, hourly_price_per_node=0.10)])
+
+    assert findings[0].estimated_impact == 219.0
+
+
+def test_monthly_cost_is_rounded_to_two_decimals(tmp_path: Path) -> None:
+    findings = run_policy(tmp_path, [nodepool(node_count=2, hourly_price_per_node=0.0777)])
+
+    assert findings[0].estimated_impact == 113.44
+
+
+def test_cpu_at_the_threshold_is_not_flagged(tmp_path: Path) -> None:
+    findings = run_policy(tmp_path, [nodepool(avg_cpu_percent=10.0)])
+
+    assert findings == []
+
+
+def test_busy_nodepool_is_not_flagged(tmp_path: Path) -> None:
+    findings = run_policy(tmp_path, [nodepool(avg_cpu_percent=45.0)])
+
+    assert findings == []
+
+
+def test_nodepool_without_a_price_is_not_flagged(tmp_path: Path) -> None:
+    findings = run_policy(tmp_path, [nodepool(hourly_price_per_node=0.0)])
+
+    assert findings == []
+
+
+def test_only_idle_nodepools_are_returned_from_a_mixed_table(tmp_path: Path) -> None:
+    rows = [
+        nodepool(resource_id="idle", avg_cpu_percent=2.0),
+        nodepool(resource_id="busy", avg_cpu_percent=60.0),
+        nodepool(resource_id="unpriced", avg_cpu_percent=1.0, hourly_price_per_node=0.0),
+    ]
+
+    findings = run_policy(tmp_path, rows)
+
+    assert [f.resource_id for f in findings] == ["idle"]
+
+
+def test_empty_table_returns_no_findings(tmp_path: Path) -> None:
+    assert run_policy(tmp_path, []) == []