Function createXRefStream

src/parser/xref-parser.test.ts:437–490

* Helper to create an XRef stream with given entries. * Uses uncompressed stream for testing (no Filter).

(
      entries: Array<{ objNum: number; type: 0 | 1 | 2; field2: number; field3: number }>,
      options: { w?: [number, number, number]; index?: number[] } = {},
    )

     * Uses uncompressed stream for testing (no Filter).
     */
    function createXRefStream(
      entries: Array<{ objNum: number; type: 0 | 1 | 2; field2: number; field3: number }>,
      options: { w?: [number, number, number]; index?: number[] } = {},
    ): Uint8Array {
      const w = options.w ?? [1, 3, 2]; // Default: 1 byte type, 3 byte offset, 2 byte gen
      const [w1, w2, w3] = w;

      // Build index array from entries if not provided
      let indexArray = options.index;
      if (!indexArray) {
        // Simple case: contiguous from min to max
        const objNums = entries.map(e => e.objNum).sort((a, b) => a - b);
        const first = objNums[0];
        const count = objNums[objNums.length - 1] - first + 1;
        indexArray = [first, count];
      }

      // Build binary data
      const data: number[] = [];
      for (const entry of entries) {
        // Type field
        const type = entry.type;
        for (let i = w1 - 1; i >= 0; i--) {
          data.push((type >> (i * 8)) & 0xff);
        }
        // Field 2
        const f2 = entry.field2;
        for (let i = w2 - 1; i >= 0; i--) {
          data.push((f2 >> (i * 8)) & 0xff);
        }
        // Field 3
        const f3 = entry.field3;
        for (let i = w3 - 1; i >= 0; i--) {
          data.push((f3 >> (i * 8)) & 0xff);
        }
      }

      const streamData = new Uint8Array(data);

      // Build the object
      const size = Math.max(...entries.map(e => e.objNum)) + 1;
      const dictStr = `<< /Type /XRef /Size ${size} /W [${w.join(" ")}] /Index [${indexArray.join(" ")}] /Length ${streamData.length} /Root 1 0 R >>`;

      // Create full indirect object
      const header = new TextEncoder().encode(`99 0 obj\n${dictStr}\nstream\n`);
      const footer = new TextEncoder().encode(`\nendstream\nendobj\n`);

      const result = new Uint8Array(header.length + streamData.length + footer.length);
      result.set(header, 0);
      result.set(streamData, header.length);
      result.set(footer, header.length + streamData.length);

      return result;
    }

    it("parses xref stream with uncompressed entries", async () => {
      const bytes = createXRefStream([