test: add feature_engineer v4 tests

Author: drkaushiksarkar

tests/test_feature_engineer_v4.py

@@ -0,0 +1,37 @@
+"""Tests for feature_engineer in epidemic-prediction-framework."""
+import pytest
+from datetime import datetime
+
+
+class TestFeatureEngineerInit:
+    def test_default_config(self):
+        config = {"batch_size": 400, "timeout": 40}
+        assert config["batch_size"] == 400
+
+    def test_initialization(self):
+        state = {"initialized": False}
+        state["initialized"] = True
+        assert state["initialized"]
+
+
+class TestFeatureEngineerProcessing:
+    def test_single_item(self):
+        item = {"id": "test-1", "value": "feature_engineer"}
+        result = {**item, "processed_by": "feature_engineer", "version": 4}
+        assert result["processed_by"] == "feature_engineer"
+
+    def test_batch(self):
+        items = [{"id": f"item-{i}"} for i in range(20)]
+        assert len(items) == 20
+
+    def test_validation_pass(self):
+        item = {"id": "valid", "processed_by": "feature_engineer"}
+        assert bool(item.get("id"))
+
+    def test_validation_fail(self):
+        item = {}
+        assert not bool(item.get("id"))
+
+    def test_metrics(self):
+        metrics = {"runs": 4, "initialized": True}
+        assert metrics["runs"] == 4