Replace test for 'get_dates'

Why these changes are being introduced:
* The record stub now available for testing negates the need for an XML file solely for
checking invalid date formats.

tests/sources/xml/test_oai_dc.py

@@ -5,8 +5,6 @@
 import transmogrifier.models as timdex
 from transmogrifier.sources.xml.oaidc import OaiDc
 
-FIXTURES_PREFIX = "tests/fixtures/oai_dc"
-
 
 def create_oai_dc_source_record_stub(xml_insert: str) -> BeautifulSoup:
     xml_str = f"""
@@ -184,6 +182,15 @@ def test_get_dates_transforms_correctly_if_fields_missing(
     )
 
 
+def test_get_dates_transforms_correctly_if_date_invalid():
+    source_record = create_oai_dc_source_record_stub(
+        """
+        <dc:date>INVALID</dc:date>
+        """
+    )
+    assert OaiDc.get_dates(source_record_id="abc", source_record=source_record) == []
+
+
 def test_get_identifiers_success(oai_dc_record_all_fields):
     assert OaiDc.get_identifiers(oai_dc_record_all_fields) == [
         timdex.Identifier(value="oai:libguides.com:guides/175846", kind="OAI-PMH")
@@ -272,14 +279,3 @@ def test_get_summary_transforms_properly_if_fields_missing(
     oai_dc_record_optional_fields_missing,
 ):
     assert OaiDc.get_summary(oai_dc_record_optional_fields_missing) == []
-
-
-def test_oaidc_generic_date():
-    source_records = OaiDc.parse_source_file(
-        f"{FIXTURES_PREFIX}/oaidc_record_valid_generic_date.xml"
-    )
-    transformer_instance = OaiDc("libguides", source_records)
-    xml = next(transformer_instance.source_records)
-    assert transformer_instance.get_dates("test_source_record_id", xml) == [
-        timdex.Date(kind="Unknown", note=None, range=None, value="2008-06-19T17:55:27")
-    ]