Dev eventmetadata class implementation (#823)

* add new namespac (ng package) for new architecture implementations

* update changelog

* add abstract event metadata class

* implement concrete kafka metaclass

* add unittests for kafka metaclass

* update CHANGELOG.md

* temporarily disable pylint warning for abstract EventMetadata class

* refactor: fix some typos ind docs

* refactor: fix doc

* Update CHANGELOG.md

Co-authored-by: kmeinerz <meinerzkai@gmail.com>

* Update CHANGELOG.md

Co-authored-by: kmeinerz <meinerzkai@gmail.com>

* remove unnecessary tests

---------

Co-authored-by: kmeinerz <meinerzkai@gmail.com>

Author: kaya-david

CHANGELOG.md

@@ -4,7 +4,11 @@
 ### Breaking
 
 ### Features
+
 ### Improvements
+* add ng packages as namespace in dirs 'unit' and 'logprep' as preparation for new architecture implementation
+* add abstract EventMetadata class and KafkaInputMetadata class
+
 ### Bugfix
 
 ## 17.0.0

logprep/ng/__init__.py

@@ -0,0 +1,10 @@
+# pylint: disable=too-few-public-methods
+# -> deactivate temporarily pylint issue here
+
+"""abstract module for event related datatypes"""
+
+from abc import ABC
+
+
+class EventMetadata(ABC):
+    """Abstract EventMetadata Class to define the Interface"""

logprep/ng/abc/event_metadata.py

@@ -0,0 +1,13 @@
+"""kafka input classes and logic"""
+
+import attrs
+
+from logprep.ng.abc.event_metadata import EventMetadata
+
+
+@attrs.define(slots=True, kw_only=True)
+class KafkaInputMetadata(EventMetadata):
+    """Concrete EventMetadata holding Kafka input metadata."""
+
+    partition: int = attrs.field(validator=attrs.validators.instance_of(int))
+    offset: int = attrs.field(validator=attrs.validators.instance_of(int))

logprep/ng/inputs/__init__.py

@@ -0,0 +1,36 @@
+# pylint: disable=missing-docstring
+# pylint: disable=attribute-defined-outside-init
+
+import pytest
+
+from logprep.ng.abc.event_metadata import EventMetadata
+from logprep.ng.inputs.kafka_input import KafkaInputMetadata
+
+
+class TestKafkaInputMetadata:
+    def test_inherits_event_metadata(self):
+        meta = KafkaInputMetadata(partition=1, offset=0)
+        assert isinstance(meta, EventMetadata)
+
+    def test_valid_instantiation(self):
+        meta = KafkaInputMetadata(partition=3, offset=100)
+        assert meta.partition == 3
+        assert meta.offset == 100
+
+    @pytest.mark.parametrize("invalid_partition", ["0", None, 1.5, [], {}])
+    def test_invalid_partition_type_raises(self, invalid_partition):
+        with pytest.raises(TypeError):
+            KafkaInputMetadata(partition=invalid_partition, offset=10)
+
+    @pytest.mark.parametrize("invalid_offset", ["0", None, 1.5, [], {}])
+    def test_invalid_offset_type_raises(self, invalid_offset):
+        with pytest.raises(TypeError):
+            KafkaInputMetadata(partition=1, offset=invalid_offset)
+
+    def test_slots_are_used(self):
+        assert hasattr(KafkaInputMetadata, "__slots__")
+
+    def test_accessing_unknown_attribute_raises(self):
+        meta = KafkaInputMetadata(partition=1, offset=2)
+        with pytest.raises(AttributeError):
+            getattr(meta, "topic")