turf/packages/turf-line-offset/test.ts

import fs from "fs";
import test from "tape";
import path from "path";
import { fileURLToPath } from "url";
import { loadJsonFileSync } from "load-json-file";
import { writeJsonFileSync } from "write-json-file";
import { truncate } from "@turf/truncate";
import { featureCollection, lineString } from "@turf/helpers";
import { lineOffset } from "./index.js";

const __dirname = path.dirname(fileURLToPath(import.meta.url));

const directories = {
  in: path.join(__dirname, "test", "in") + path.sep,
  out: path.join(__dirname, "test", "out") + path.sep,
};

let fixtures = fs.readdirSync(directories.in).map((filename) => {
  return {
    filename,
    name: path.parse(filename).name,
    geojson: loadJsonFileSync(directories.in + filename),
  };
});
// fixtures = fixtures.filter(fixture => fixture.name === 'polygon');

test("turf-line-offset", (t) => {
  fixtures.forEach((fixture) => {
    const name = fixture.name;
    const geojson = fixture.geojson as any;
    const properties = geojson.properties || {};
    const distance = properties.distance || 50;
    const units = properties.units;

    const output = truncate(lineOffset(geojson, distance, { units: units }), {
      precision: 4,
    });
    output.properties!.stroke = "#00F";
    const results = featureCollection([output, geojson]);

    if (process.env.REGEN)
      writeJsonFileSync(directories.out + name + ".geojson", results);
    t.deepEqual(
      results,
      loadJsonFileSync(directories.out + name + ".geojson"),
      name
    );
  });
  t.end();
});

test("turf-line-offset - Throws Errors", (t) => {
  const line = lineString([
    [10, 10],
    [0, 0],
  ]);
  t.throws(() => (lineOffset as any)(), /geojson is required/);
  t.throws(() => (lineOffset as any)(line), /distance is required/);
  t.end();
});

test("turf-line-offset - Support Geometry Objects", (t) => {
  const line = lineString([
    [10, 10],
    [0, 0],
  ]);
  t.ok(lineOffset(line.geometry, 10), "Geometry Object");
  t.end();
});

test("turf-line-offset - Prevent Input Mutation", (t) => {
  const line = lineString([
    [10, 10],
    [0, 0],
  ]);
  const before = JSON.parse(JSON.stringify(line));
  lineOffset(line.geometry, 10);

  t.deepEqual(line, before, "input does not mutate");
  t.end();
});