Instrument vite (rollup) React Typescript project with istanbul

istanbul-plugin.ts

/**
 * Coverage instrumentation with working source maps.
 * Use as rollup or vite plugin.
 */

import { createInstrumenter } from "istanbul-lib-instrument";
import { Plugin } from "rollup";
import { createFilter } from "@rollup/pluginutils";

const filter = createFilter("src/**/*.(js|jsx|ts|tsx)");

const plugin: Plugin = {
  name: "istanbul",
  transform(code, id) {
    if (!filter(id)) {
      return;
    }

    const instrumenter = createInstrumenter({
      esModules: true,
      compact: true,
      produceSourceMap: true,
      autoWrap: true,
      preserveComments: true,
    });
    
    const combinedSourceMap = this.getCombinedSourcemap();

    const transformedCode = instrumenter.instrumentSync(code, id, {
      ...combinedSourceMap,
      version: String(combinedSourceMap.version),
    });

    const sourceMap = instrumenter.lastSourceMap();

    return {
      code: transformedCode,
      map: { ...sourceMap, version: Number(sourceMap.version) },
    };
  },
};

export default plugin;