internal/endtoend: Add update test for named params (#329)

Author: kyleconroy

internal/endtoend/testdata/named_param/go/query.sql.go

@@ -5,3 +5,12 @@ SELECT name FROM foo WHERE name = sqlc.arg(slug) AND sqlc.arg(filter)::bool;
 
 -- name: AtParams :many
 SELECT name FROM foo WHERE name = @slug AND @filter::bool;
+
+-- name: Update :one
+UPDATE foo
+SET
+  name = CASE WHEN @set_name::bool
+    THEN @name::text
+    ELSE name
+    END
+RETURNING *;