feat: add cdr processing worker and dlq routing

tests/unit/test_dlq.py

@@ -0,0 +1,36 @@
+from core.domain.errors import (
+    CDRProcessingError,
+    FailureReason,
+)
+from core.worker.dlq import build_dlq_envelope
+
+
+def test_build_dlq_envelope() -> None:
+    original = {
+        "raw_id": "raw-invalid-001",
+        "rat": 99,
+    }
+
+    error = CDRProcessingError(
+        reason=FailureReason.INVALID_RAT_VALUE,
+        detail="Unsupported RAT value: 99.",
+        failed_field="rat",
+    )
+
+    envelope = build_dlq_envelope(
+        original_payload=original,
+        error=error,
+        worker_instance="worker-test",
+    )
+
+    assert envelope["original_payload"] == original
+
+    assert (
+        envelope["failure_reason"]
+        == "invalid_rat_value"
+    )
+
+    assert envelope["failed_field"] == "rat"
+    assert envelope["worker_instance"] == "worker-test"
+
+    assert envelope["failed_at"].endswith("Z")

tests/unit/test_worker_processor.py

@@ -0,0 +1,78 @@
+import json
+
+import pytest
+
+from core.domain.errors import (
+    CDRProcessingError,
+    FailureReason,
+)
+from core.worker.processor import (
+    decode_payload,
+    process_payload,
+)
+
+
+def valid_payload() -> dict:
+    return {
+        "raw_id": "raw-worker-001",
+        "src_ip": "10.240.12.1",
+        "device_id": "310410998877665",
+        "caller_num": "0019875551234",
+        "svc": "4G_DATA",
+        "up_bytes": 100,
+        "down_bytes": 200,
+        "rat": 6,
+        "lac": "4021",
+        "ci": "8812",
+        "epoch_start": 1789900000,
+        "epoch_end": 1789900300,
+    }
+
+
+def test_decode_valid_json_object() -> None:
+    value = json.dumps(
+        valid_payload()
+    ).encode("utf-8")
+
+    payload = decode_payload(value)
+
+    assert payload == valid_payload()
+
+
+def test_malformed_json() -> None:
+    with pytest.raises(
+        CDRProcessingError
+    ) as exc_info:
+        decode_payload(
+            b'{"raw_id": invalid}'
+        )
+
+    assert (
+        exc_info.value.reason
+        == FailureReason.MALFORMED_JSON
+    )
+
+
+def test_json_array_is_rejected() -> None:
+    with pytest.raises(
+        CDRProcessingError
+    ) as exc_info:
+        decode_payload(
+            b'["not", "a", "cdr"]'
+        )
+
+    assert (
+        exc_info.value.reason
+        == FailureReason.NORMALIZATION_ERROR
+    )
+
+
+def test_worker_normalizes_valid_payload() -> None:
+    normalized = process_payload(
+        valid_payload()
+    )
+
+    assert normalized.raw_id == "raw-worker-001"
+    assert normalized.radio_access_type == "LTE_4G"
+    assert normalized.total_bytes == 300
+    assert normalized.duration_seconds == 300