test: Add test for no functions registered error

datafusion/sql/tests/sql_integration.rs

@@ -4436,3 +4436,23 @@ fn init() {
     // Enable RUST_LOG logging configuration for tests
     let _ = env_logger::try_init();
 }
+
+#[test]
+fn test_no_functions_registered() {
+    let sql = "SELECT foo()";
+
+    let options = ParserOptions::default();
+    let dialect = &GenericDialect {};
+    let state = MockSessionState::default();
+    let context = MockContextProvider { state };
+    let planner = SqlToRel::new_with_options(&context, options);
+    let result = DFParser::parse_sql_with_dialect(sql, dialect);
+    let mut ast = result.unwrap();
+
+    let err = planner.statement_to_plan(ast.pop_front().unwrap());
+
+    assert_contains!(
+        err.unwrap_err().to_string(),
+        "Internal error: No functions registered with this context."
+    );
+}