javascript/test/metastring.test.ts

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 * to you under the Apache License, Version 2.0 (the
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 *   http://www.apache.org/licenses/LICENSE-2.0
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import { MetaStringReader, MetaStringWriter } from "../packages/core/lib/context";
import {
  Encoding,
  MetaStringDecoder,
  MetaStringEncoder,
} from "../packages/core/lib/meta/MetaString";
import { BinaryReader } from "../packages/core/lib/reader";
import { BinaryWriter } from "../packages/core/lib/writer";
import { describe, expect, test } from "@jest/globals";

function readerFor(bytes: Uint8Array): BinaryReader {
  const reader = new BinaryReader({});
  reader.reset(bytes);
  return reader;
}

describe("meta string", () => {
  test("rejects a trailing uppercase marker", () => {
    const encoded = new MetaStringEncoder("$", "_").encodeByEncoding(
      "|",
      Encoding.ALL_TO_LOWER_SPECIAL,
    );
    const reader = readerFor(encoded.getBytes());
    const decoder = new MetaStringDecoder("$", "_");

    expect(() =>
      decoder.decode(reader, encoded.getBytes().length, Encoding.ALL_TO_LOWER_SPECIAL),
    ).toThrow("Malformed ALL_TO_LOWER_SPECIAL encoding: trailing uppercase marker");
  });

  test("round trips dynamic references", () => {
    const metaStringWriter = new MetaStringWriter();
    const first = metaStringWriter.encodeTypeName("first");
    const second = metaStringWriter.encodeTypeName("second");
    const writer = new BinaryWriter({});
    metaStringWriter.writeBytes(writer, first);
    metaStringWriter.writeBytes(writer, second);
    metaStringWriter.writeBytes(writer, first);

    const reader = readerFor(writer.dump());
    const metaStringReader = new MetaStringReader();
    expect(metaStringReader.readTypeName(reader)).toBe("first");
    expect(metaStringReader.readTypeName(reader)).toBe("second");
    expect(metaStringReader.readTypeName(reader)).toBe("first");
  });
});