testFailure

fn testFailure(container: Container, in: []const u8, expected_err: anyerror) !void {
    var reader: Reader = .fixed(in);
    var aw: Writer.Allocating = .init(testing.allocator);
    defer aw.deinit();

    var decompress: Decompress = .init(&reader, container, &.{});
    try testing.expectError(error.ReadFailed, decompress.reader.streamRemaining(&aw.writer));
    try testing.expectEqual(expected_err, decompress.err orelse return error.TestFailed);
}