diff --git a/backend/pashub_fetcher/core_files.py b/backend/pashub_fetcher/core_files.py
index 01ae189f..e668ba7f 100644
--- a/backend/pashub_fetcher/core_files.py
+++ b/backend/pashub_fetcher/core_files.py
@@ -38,24 +38,33 @@ _CORE_FILE_TO_FILE_TYPE: dict[CoreFiles, str] = {
 def core_file_for(
     filename: str, evidence_category: Optional[str] = None
 ) -> Optional[CoreFiles]:
+    # Identify retrofit design doc using evidence category as the name is possibly unreliable.
+    # We might change to always use evidence category, but needs more investigation
     if evidence_category is not None and evidence_category.lower() == "retrofit design":
         return CoreFiles.RETROFIT_DESIGN_DOC
+
     if CoreFiles.IMPROVEMENT_OPTION_EVALUATION.value in filename:
         return CoreFiles.IMPROVEMENT_OPTION_EVALUATION
+
     if CoreFiles.MEDIUM_TERM_IMPROVEMENT_PLAN.value in filename:
         return CoreFiles.MEDIUM_TERM_IMPROVEMENT_PLAN
+
     if evidence_category is None and "-OSM-" in filename and "DR-N-A" in filename:
         return CoreFiles.RETROFIT_DESIGN_DOC
+
     _prefix_skip = {
         CoreFiles.RETROFIT_DESIGN_DOC,
         CoreFiles.IMPROVEMENT_OPTION_EVALUATION,
         CoreFiles.MEDIUM_TERM_IMPROVEMENT_PLAN,
     }
+
     for core_file in CoreFiles:
         if core_file in _prefix_skip:
             continue
+
         if filename.startswith(core_file.value):
             return core_file
+
     return None
 
 
diff --git a/backend/pashub_fetcher/tests/test_core_files.py b/backend/pashub_fetcher/tests/test_core_files.py
index 09fcdcb2..ee91298e 100644
--- a/backend/pashub_fetcher/tests/test_core_files.py
+++ b/backend/pashub_fetcher/tests/test_core_files.py
@@ -1,62 +1,58 @@
 from backend.pashub_fetcher.core_files import CoreFiles, core_file_for, file_type_for
 
 
-def test_infer_photopack():
+def test_file_type_for_photopack():
     assert file_type_for("Photopack_123456_V1.pdf") == "photo_pack"
 
 
-def test_infer_sitenote():
+def test_file_type_for_sitenote():
     assert file_type_for("SiteNote_123456_V1.pdf") == "site_note"
 
 
-def test_infer_rdsap_sitenote():
+def test_file_type_for_rdsap_sitenote():
     assert (
         file_type_for("RdSAP_SiteNote_9510890_V1_Assessmet.pdf") == "rd_sap_site_note"
     )
 
 
-def test_infer_pas2023_ventilation():
+def test_file_type_for_pas2023_ventilation():
     assert (
         file_type_for("PAS 2023 Ventilation Assessment Report_123456.pdf")
         == "pas_2023_ventilation"
     )
 
 
-def test_infer_pas2023_condition():
+def test_file_type_for_pas2023_condition():
     assert (
         file_type_for("PAS 2023 Condition Report_123456.pdf") == "pas_2023_condition"
     )
 
 
-def test_infer_pas_significance():
+def test_file_type_for_pas_significance():
     assert file_type_for("PAS Significance_123456.pdf") == "pas_significance"
 
 
-def test_infer_par_photopack():
+def test_file_type_for_par_photopack():
     assert (
         file_type_for("PAR Photo Pack_95101890_V2_Assessment.pdf") == "par_photo_pack"
     )
 
 
-def test_infer_pas2023_property():
+def test_file_type_for_pas2023_property():
     assert (
         file_type_for("PAS 2023 Property Assessment Report_123456.pdf")
         == "pas_2023_property"
     )
 
 
-def test_infer_pas2023_occupancy():
+def test_file_type_for_pas2023_occupancy():
     assert (
         file_type_for("PAS 2023 Occupancy Assessment Report_123456.pdf")
         == "pas_2023_occupancy"
     )
 
 
-def test_infer_unknown_returns_none():
-    assert file_type_for("unknown_document_123.pdf") is None
-
-
-def test_infer_improvement_option_evaluation():
+def test_file_type_for_improvement_option_evaluation():
     # filename: "{job_id} - {postcode} - Improvement Option Evaluation.pdf"
     assert (
         file_type_for("6000802 - NG4 4HD - Improvement Option Evaluation.pdf")
@@ -64,7 +60,7 @@ def test_infer_improvement_option_evaluation():
     )
 
 
-def test_infer_medium_term_improvement_plan():
+def test_file_type_for_medium_term_improvement_plan():
     # filename: "{job_id} - {postcode} - Medium Term Improvement Plan IOE.pdf"
     assert (
         file_type_for("60800802 - NG4 4HD - Medium Term Improvement Plan IOE.pdf")
@@ -72,7 +68,7 @@ def test_infer_medium_term_improvement_plan():
     )
 
 
-def test_infer_retrofit_design_doc():
+def test_file_type_for_retrofit_design_doc():
     assert (
         file_type_for("2512-OSM-H21M900-XX-DR-N-A_Lord Nelson Street 018.pdf")
         == "retrofit_design_doc"