should be it

external/duckdb/test/sql/upsert/upsert_coverage.test

@@ -0,0 +1,36 @@
+# name: test/sql/upsert/upsert_coverage.test
+# group: [upsert]
+
+statement ok
+PRAGMA enable_verification;
+
+statement ok
+CREATE TABLE tbl (a INT, b INT UNIQUE, c INT UNIQUE, d INT UNIQUE);
+
+statement ok
+INSERT INTO tbl (b, c, d) VALUES (1, 2, 3), (2, 3, 1), (3, 1, 2)
+
+# Create conflicts in three existing tuples with one INSERT tuple.
+# Each conflict has a different row ID.
+
+# We never have to deal with one-to-many conflicts in anything other than
+# a DO NOTHING action. That is because we need a conflict target
+# to use any sort of WHERE or SET expression that references the existing table.
+
+statement ok
+INSERT INTO tbl(b, c, d) VALUES (3, 3, 3) ON CONFLICT DO NOTHING;
+
+query III
+SELECT b, c, d FROM tbl ORDER BY ALL;
+----
+1	2	3
+2	3	1
+3	1	2
+
+# We fail without a conflict target.
+
+statement error
+INSERT INTO tbl(b, c, d) VALUES (3, 3, 3)
+ON CONFLICT DO UPDATE SET b = EXCLUDED.b, c = EXCLUDED.c, d = EXCLUDED.d;
+----
+<REGEX>:Binder Error.*Conflict target has to be provided for a DO UPDATE operation when the table has multiple UNIQUE/PRIMARY KEY constraints.*