diff --git a/ebpf_trace_instrumentation/tests/test_core.py b/ebpf_trace_instrumentation/tests/test_core.py
new file mode 100644
index 0000000..b3c7bf1
--- /dev/null
+++ b/ebpf_trace_instrumentation/tests/test_core.py
@@ -0,0 +1,94 @@
+import pytest
+import json
+from pathlib import Path
+from src.ebpf_trace_instrumentation import core
+
+@pytest.fixture
+def sample_event_data():
+    return {
+        "ktime_ns": 1234567890,
+        "CPU": 2,
+        "field_tag": "clocksource_id",
+        "new_value_hash": 998877,
+        "corr_id": "corr-001"
+    }
+
+@pytest.fixture
+def invalid_event_data():
+    # Missing required fields intentionally
+    return {"ktime_ns": "invalid", "CPU": "NaN"}
+
+
+def test_publish_event_init_valid(sample_event_data):
+    ev = core.PublishEvent(**sample_event_data)
+    assert ev.ktime_ns == 1234567890
+    assert ev.CPU == 2
+    assert ev.field_tag == "clocksource_id"
+    assert ev.new_value_hash == 998877
+    assert ev.corr_id == "corr-001"
+
+
+def test_publish_event_init_type_validation(sample_event_data):
+    # Validate all types match expected
+    ev = core.PublishEvent(**sample_event_data)
+    assert isinstance(ev.ktime_ns, int)
+    assert isinstance(ev.CPU, int)
+    assert isinstance(ev.field_tag, str)
+    assert isinstance(ev.new_value_hash, int)
+    assert isinstance(ev.corr_id, str)
+
+
+def test_add_event_appends(monkeypatch, sample_event_data):
+    # Mock internal collection
+    collected = []
+
+    def mock_append(e):
+        collected.append(e)
+
+    monkeypatch.setattr(core, "_event_log", collected)
+
+    core.add_event("clocksource_id", sample_event_data)
+    assert len(collected) == 1
+    added_event = collected[0]
+    assert isinstance(added_event, core.PublishEvent)
+    assert added_event.field_tag == "clocksource_id"
+
+
+def test_add_event_invalid_input(monkeypatch, invalid_event_data):
+    collected = []
+
+    def mock_append(e):
+        collected.append(e)
+
+    monkeypatch.setattr(core, "_event_log", collected)
+    with pytest.raises((TypeError, ValueError)):
+        core.add_event("invalid", invalid_event_data)
+
+
+def test_add_event_multiple_calls(monkeypatch, sample_event_data):
+    collected = []
+
+    def mock_append(e):
+        collected.append(e)
+
+    monkeypatch.setattr(core, "_event_log", collected)
+
+    for i in range(5):
+        core.add_event(f"field_{i}", sample_event_data)
+
+    assert len(collected) == 5
+    assert all(isinstance(e, core.PublishEvent) for e in collected)
+
+    tags = [e.field_tag for e in collected]
+    assert tags == [f"field_{i}" for i in range(5)]
+
+
+def test_event_json_serialization(tmp_path, sample_event_data):
+    ev = core.PublishEvent(**sample_event_data)
+    file_path = tmp_path / "event.json"
+    with open(file_path, "w", encoding="utf-8") as f:
+        json.dump(ev.__dict__, f)
+
+    with open(file_path, encoding="utf-8") as f:
+        loaded = json.load(f)
+    assert loaded == sample_event_data
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