How do you ensure code coverage for files with no matching spec files in an Angular 7 app?

Question

This question has been asked before but all answers appear to be out of date and do not result in full code coverage including coverage for files with no spec file.

When I run the command ng-test --code-coverage my results show far fewer source code checked than reality, because it is skiping files with no matching spec file. I have tried to solve this in a few ways including creating an app.module.spec file and importing app.module into it and this increased the reported tested lines of code, but after adding a new component without tests to a deeply nested module the numbers did not change.

Here is my karma config:

// Karma configuration file, see link for more information
// https://karma-runner.github.io/1.0/config/configuration-file.html

module.exports = function (config) {
  config.set({
    basePath: '',
    frameworks: ['jasmine', '@angular-devkit/build-angular'],
    plugins: [
      require('karma-jasmine'),
      require('karma-chrome-launcher'),
      require('karma-jasmine-html-reporter'),
      require('karma-mocha-reporter'),
      require('karma-coverage-istanbul-reporter'),
      require('@angular-devkit/build-angular/plugins/karma')
    ],
    client: {
      clearContext: false // leave Jasmine Spec Runner output visible in browser
    },
    coverageIstanbulReporter: {
      dir: require('path').join(__dirname, '../coverage'),
      reports: ['html', 'lcovonly', 'text-summary'],
      fixWebpackSourcePaths: true,
      thresholds: {
        statements: 80,
        lines: 80,
        branches: 80,
        functions: 80
      }
    },
    mochaReporter: {
      maxLogLines: 4
    },
    reporters: ['progress', 'mocha', 'kjhtml'],
    port: 9876,
    colors: true,
    logLevel: config.LOG_INFO,
    autoWatch: true,
    browsers: ['Chrome'],
    singleRun: false
  });
};

here is my tests.ts file

// This file is required by karma.conf.js and loads recursively all the .spec and framework files

import 'zone.js/dist/zone-testing';
import { getTestBed } from '@angular/core/testing';
import {
  BrowserDynamicTestingModule,
  platformBrowserDynamicTesting
} from '@angular/platform-browser-dynamic/testing';

declare const require: any;

// First, initialize the Angular testing environment.
getTestBed().initTestEnvironment(
  BrowserDynamicTestingModule,
  platformBrowserDynamicTesting()
);
// Then we find all the tests.
const context = require.context('./', true, /\.spec\.ts$/);
// And load the modules.
context.keys().map(context);

Here is my tsconfig.spec.json file:

{
  "extends": "../tsconfig.json",
  "compilerOptions": {
    "outDir": "../out-tsc/spec",
    "types": [
      "jasmine",
      "node"
    ]
  },
  "files": [
    "test.ts",
    "polyfills.ts"
  ],
  "include": [
    "**/*.spec.ts",
    "**/*.d.ts"
  ]
}

Answer 1

I ended up deciding to write a schematic that generates missing spec files with absolute basic test implementations - just enough to new up components and services. Now my code coverage report looks correct.