Test, refactor and comment closest_match

Co-authored-by: Florentin Dörre <florentin.dorre@neotechnology.com>

Author: Mats-SX

graphdatascience/gds_session/gds_sessions.py

@@ -135,12 +135,13 @@ def _ds_region(self, region: str, cloud_provider: str) -> str:
         tenant_details = self._aura_api.tenant_details()
         available_regions = tenant_details.regions_per_provider[cloud_provider]
 
-        if not available_regions:
+        match = closest_match(region, available_regions)
+        if not match:
             raise ValueError(
                 f"Tenant `{tenant_details.id}` cannot create GDS sessions at cloud provider `{cloud_provider}`."
             )
 
-        return closest_match(region, available_regions)
+        return match
 
     def _construct_client(
         self, session_name: str, gds_url: str, db_connection: DbmsConnectionInfo

graphdatascience/gds_session/region_suggester.py

@@ -1,17 +1,17 @@
-from typing import Iterable
+from typing import Iterable, Optional
 
 import textdistance
 
 
-def closest_match(query: str, options: Iterable[str]) -> str:
-    if not options:
-        raise ValueError("No options to choose from.")
-
+# AuraDB and AuraDS regions are not the same, so we need to find the closest match.
+def closest_match(db_region: str, ds_regions: Iterable[str]) -> Optional[str]:
     curr_max_similarity = 0.0
-    for ep in options:
-        similarity = textdistance.jaro_winkler(query, ep)
+    closest_option = None
+
+    for region in ds_regions:
+        similarity = textdistance.jaro_winkler(db_region, region)
         if similarity > curr_max_similarity:
-            closest_option = ep
+            closest_option = region
             curr_max_similarity = similarity
 
     return closest_option

graphdatascience/tests/unit/test_region_suggester.py

@@ -0,0 +1,21 @@
+from graphdatascience.gds_session import region_suggester
+
+
+def test_picks_the_only_option() -> None:
+    match = region_suggester.closest_match("db_region", ["ds_region1"])
+    assert match == "ds_region1"
+
+
+def test_picks_the_closest() -> None:
+    match = region_suggester.closest_match("eu-1", ["us-1", "aa-1", "ea-1", "eu-4"])
+    assert match == "eu-4"
+
+
+def test_picks_exact_match() -> None:
+    match = region_suggester.closest_match("eu-2", ["eu-1", "eu-2", "eu-3"])
+    assert match == "eu-2"
+
+
+def test_no_options() -> None:
+    match = region_suggester.closest_match("eu-2", [])
+    assert match is None