From e47382d4abb8ced3f4c7956b60c55d82b7c87d52 Mon Sep 17 00:00:00 2001
From: Tom Parker-Shemilt <palfrey@tevp.net>
Date: Wed, 21 Dec 2022 08:19:39 +0000
Subject: [PATCH] Better error on missing schema (#196)

---
 dj_database_url.py      | 8 +++++++-
 test_dj_database_url.py | 4 ++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/dj_database_url.py b/dj_database_url.py
index 39f7405..ac194a4 100644
--- a/dj_database_url.py
+++ b/dj_database_url.py
@@ -115,7 +115,13 @@ def parse(
         hostname = urlparse.unquote(hostname)
 
     # Lookup specified engine.
-    engine = SCHEMES[url.scheme] if engine is None else engine
+    if engine is None:
+        engine = SCHEMES.get(url.scheme)
+        if engine is None:
+            raise ValueError(
+                "No support for '%s'. We support: %s"
+                % (url.scheme, ", ".join(sorted(SCHEMES.keys())))
+            )
 
     port = (
         str(url.port)
diff --git a/test_dj_database_url.py b/test_dj_database_url.py
index a10625a..0ed8b02 100644
--- a/test_dj_database_url.py
+++ b/test_dj_database_url.py
@@ -541,6 +541,10 @@ def test_persistent_connection_variables_config(self):
         assert url["CONN_MAX_AGE"] == 600
         assert url["CONN_HEALTH_CHECKS"] is True
 
+    def test_bad_url_parsing(self):
+        with self.assertRaisesRegex(ValueError, "No support for 'foo'. We support: "):
+            dj_database_url.parse("foo://bar")
+
 
 if __name__ == "__main__":
     unittest.main()