ng test: Collect total code coverage in multi project repository

まず ng test を使ってマルチプロジェクト workspace のケースを再現し、次に application および library schematics 配下の、参照されている karma.conf.js ファイルを調べます。coverage の処理が builder と schematic のどちらに属するのかを追跡します。完了の条件は、各プロジェクトが独自の lcov データを持ち、結合されたレポートで合計 coverage を表現できることです。

Bug Report or Feature Request (mark with an x)

- [ ] bug report -> please search issues before submitting
- [x] feature request

Area

- [x] devkit
- [ ] schematics

Versions

Angular CLI: 6.0.8
Node: 8.9.1
OS: win32 x64
Angular: 5.2.11
... animations, common, compiler, compiler-cli, core, forms
... http, language-service, platform-browser
... platform-browser-dynamic, router

Package                           Version
-----------------------------------------------------------
@angular-devkit/architect         0.6.8
@angular-devkit/build-angular     0.6.8
@angular-devkit/build-optimizer   0.6.8
@angular-devkit/core              0.6.8
@angular-devkit/schematics        0.6.8
@angular/cdk                      5.2.5
@angular/cli                      6.0.8
@ngtools/json-schema              1.1.0
@ngtools/webpack                  6.0.8
@schematics/angular               0.6.1
@schematics/update                0.6.8
ng-packagr                        3.0.2
rxjs                              6.2.1
typescript                        2.6.2
webpack                           4.8.3

Repro steps

Multi project workspace, run ng test to test all projects.

The log given by the failure

Produced coverage report in coverage/lcov.info only contains results for the last run code coverage.

HTML reports are stored per project in coverage/<project>.

Desired functionality

Write indivudual lcovs per project, e.g, coverage/<project>/lcov.info, allowing users to get a total code coverage for the whole project.

Alternative would be functionality similar to istanbul-combine. Write coverage.json for each project and write a combined coverage report and end of test runs.

Mention any other details that might be useful

Should eht changes be made in the builder or in the schematic?

https://github.com/angular/angular-cli/blob/master/packages/schematics/angular/library/files/__projectRoot__/karma.conf.js#L19

https://github.com/angular/angular-cli/blob/master/packages/schematics/angular/application/files/root/karma.conf.js#L19