Function TestHandleQueryEmitsCorrectSQLSTATEOnDuckDBErrors

server/conn_test.go:1618–1662

TestHandleQueryEmitsCorrectSQLSTATEOnDuckDBErrors exercises the full handleQuery → wire-frame path so PG-aware clients (psycopg2, SQLAlchemy, dlt) receive the SQLSTATE they branch on. The test injects canonical DuckDB error strings via the executor mock, then parses the resulting ErrorResponse frame

(t *testing.T)

// DuckDB error strings via the executor mock, then parses the resulting
// ErrorResponse frame out of the writer buffer and asserts the 'C' field.
func TestHandleQueryEmitsCorrectSQLSTATEOnDuckDBErrors(t *testing.T) {
	cases := []struct {
		name     string
		duckErr  string
		wantCode string
	}{
		{"missing table", "Catalog Error: Table with name nope does not exist!", "42P01"},
		{"missing schema", "Catalog Error: Schema with name missing_schema does not exist!", "3F000"},
		{"missing function", "Catalog Error: Scalar Function with name no_such_func does not exist!", "42883"},
		{"missing column", "Binder Error: Referenced column \"missing_col\" not found in FROM clause!", "42703"},
		{"parser syntax", "Parser Error: syntax error at or near \"FORM\"", "42601"},
		{"conversion", "Conversion Error: Could not convert string 'abc' to INT32", "22P02"},
		{"unique violation", "Constraint Error: Duplicate key \"id: 1\" violates primary key constraint", "23505"},
		{"permission", "Permission Error: not allowed to write here", "42501"},
	}

	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			clientSide, serverSide := net.Pipe()
			defer func() { _ = clientSide.Close() }()
			defer func() { _ = serverSide.Close() }()

			var out bytes.Buffer
			c := &clientConn{
				server:   &Server{activeQueries: make(map[BackendKey]context.CancelFunc)},
				conn:     clientSide,
				reader:   bufio.NewReader(clientSide),
				writer:   bufio.NewWriter(&out),
				ctx:      context.Background(),
				cancel:   func() {},
				txStatus: txStatusIdle,
				executor: &queryErrorExecutor{err: errors.New(tc.duckErr)},
			}

			if err := c.handleQuery([]byte("SELECT 1\x00")); err != nil {
				t.Fatalf("handleQuery returned error: %v", err)
			}

			code := extractErrorResponseField(t, out.Bytes(), 'C')
			if code != tc.wantCode {
				t.Fatalf("SQLSTATE: got %q, want %q (duckErr=%q)", code, tc.wantCode, tc.duckErr)
			}
		})
	}
}

// extractErrorResponseField scans wire-protocol frames for an ErrorResponse
// ('E') message and returns the requested field value (e.g., 'C' for