karma.conf.ts

import * as karma from "karma";
import * as path from "path";
import * as webpack from "webpack";

export interface IKarmaConfig extends karma.Config, IKarmaConfigOptions {
  transpileOnly?: boolean;
  noInfo?: boolean;
  coverage?: boolean;
  tsconfig?: string;
  set(config: IKarmaConfigOptions): void;
}

export interface IKarmaConfigOptions extends karma.ConfigOptions {
  webpack: webpack.Configuration;
  coverageIstanbulReporter?: any;
  webpackServer: any;
  customLaunchers: any;
}

export default (config: IKarmaConfig): void => {
  const rules: webpack.Rule[] = [];

  const options: IKarmaConfigOptions = {
    basePath: config.basePath || "./",
    frameworks: ["jasmine"],
    files: ["test/setup.ts"],
    preprocessors: {
      "test/setup.ts": ["webpack", "sourcemap"]
    },
    webpack: {
      mode: "development",
      resolve: {
        extensions: [".ts", ".js"],
        modules: ["src", "node_modules"],
        alias: {
          src: path.resolve(__dirname, "src")
        }
      },
      devtool: "cheap-module-eval-source-map",
      module: {
        rules: [
          {
            test: /\.ts$/,
            loader: "ts-loader",
            exclude: /node_modules/,
            options: {
              configFile: config.tsconfig,
              transpileOnly: config.transpileOnly
            }
          }
        ]
      }
    },
    mime: {
      "text/x-typescript": ["ts"]
    },
    reporters: ["mocha", "progress"],
    webpackServer: { noInfo: config.noInfo },
    browsers: config.browsers || ["Chrome"],
    customLaunchers: {
      ChromeDebugging: {
        base: "Chrome",
        flags: ["--remote-debugging-port=9333"],
        debug: true
      }
    }
  };

  if (config.coverage) {
    options.webpack.module.rules.push({
      enforce: "post",
      exclude: /(node_modules|\.spec\.ts$)/,
      loader: "istanbul-instrumenter-loader",
      options: { esModules: true },
      test: /src[\/\\].+\.ts$/
    });
    options.reporters.push("coverage-istanbul");
    options.coverageIstanbulReporter = {
      reports: ["html", "lcovonly", "text-summary"],
      fixWebpackSourcePaths: true
    };
  }

  config.set(options);
};