karma.conf.js

// Coverage reporting breaks breakpoints
const debug = process.argv.includes('--debug');
console.warn(`Debug mode is enabled - code coverage will be disabled`);

module.exports = (config) => {
    config.set({
        browsers: ['ChromeHeadlessDebug'],
        customLaunchers: {
            ChromeHeadlessDebug: {
                base: 'ChromeHeadless',
                flags: [ '--remote-debugging-port=9333' ],
            },
        },

        frameworks: ['jasmine'],
        reporters: ['progress', ...(debug ? [] : ['coverage-istanbul'])],

        files: [
            { pattern: './test/**/*.ts' }
        ],

        preprocessors: {
            '**/*.ts': ['webpack', 'sourcemap'],
        },

        webpack: {
            node: { fs: 'empty' },
            devtool: 'inline-source-map',
            mode: 'development',
            resolve: {
                extensions: ['.js', '.ts', '.tsx', '.json']
            },
            module: {
                rules: [
                    {test: /\.tsx?$/, use: [...(debug ? [] : ['coverage-istanbul-loader']), 'ts-loader']}
                ]
            },
            output: {
                // Outputs absolute file paths instead of webpack:///path/to/file.extension
                // This makes stacktrace paths clickable in a shell (e.g. VS Code)
                devtoolModuleFilenameTemplate: function(info) {
                    return info.absoluteResourcePath;
                },
            },
        },
        webpackMiddleware: { stats: 'errors-only' },

        coverageIstanbulReporter: {
            dir: '.coverage',
            reports: ['html', 'text-summary'],
            'report-config': {
                html: { subdir: 'html' }
            },
            // Don't run coverage on test/
            instrumentation: {
                excludes: [
                    '**/test/**'
                ]
            }
        }
    });
};