[CI] Run tests on Windows

[hramos]

For Discussion

Our suite of tests does not currently run on Windows machines. This results in a blind spot that has allowed issues affecting Windows users to creep into the code base (facebook/metro#181).

Circle CI does not support running jobs on Windows at the moment. I'd like to open a discussion and get feedback from the community on how to proceed.

[kelset]

A while back @matthargett suggested that to fix the CircleCI "Windows absence" we could integrate AppVeyor CI

[gengjiawen]

Recently babel add Appveyor too.

[charpeni]

I agree that AppVeyor CI would be a good alternative and it looks like from their homepage that Facebook is already one of their great customers.

As starting point, maybe we can introduce some basic Windows tests like:

1. Clone the repository and use the cli (from local repository) to init a fresh React Native project.
2. From this fresh project, bundle the JavaScript (local-cli/cli.js bundle).

With this we should be able to catch issues like #20015.

[gengjiawen]

I have created a pr #20281, hope it helps.

[kelset]

Yeah I think that's a "good enough" start, and then we can ask Windows dev to jump in and add more tests as the platform becomes more widely used.

[gengjiawen]

Okay, the basic setup is okay, and we can wait for facebook/metro#181 to be fixed.
Current build log: https://ci.appveyor.com/project/gengjiawen/react-native/build/job/x476xw6q46hg5h3e.

[gengjiawen]

So what test should on windows platform run ? Aside from basic android build. I also add some npm run test, but some test case are failed.

Personally I want to add metro debug server bundle works as expected.

[gengjiawen]

@hramos Can you check the appveyor config or the badge url. Looks like README.md now has not show any build in appveyor.

[gengjiawen]

The windows issue (#20353) still exists on master branch now. So we do need a test case to test the request to http://localhost:8081/RNTester/js/RNTesterApp.android.delta?platform=android&dev=true&minify=false works on windows.

I will see what I can do after my two prs got merged.

[gengjiawen]

Currently the android build works on appveyor, but we have some jest test failure.

Test Suites: 16 failed, 2 skipped, 90 passed, 106 of 108 total
Tests:       54 failed, 4 skipped, 545 passed, 603 total
Snapshots:   42 passed, 42 total
Time:        12.803s

Most of those related to On a win32 FS, the options' cwd() must return a valid win32 absolute path.

Error: On a win32 FS, the options' `cwd()` must return a valid win32 absolute path. This happened while trying to resolve: `c:\empty`

      33 |       continue;
      34 |     }
    > 35 |     fs.mkdirSync(entPath);
         |        ^
      36 |     mockDir(entPath, ent);
      37 |   }
      38 | }

      at MemoryFs._resolve (node_modules/metro-memory-fs/src/index.js:830:15)
      at MemoryFs.mkdirSync (node_modules/metro-memory-fs/src/index.js:994:5448)
      at mockDir (local-cli/__mocks__/fs.js:35:8)
      at MemoryFs.setMockFilesystem [as __setMockFilesystem] (local-cli/__mocks__/fs.js:17:3)
      at Object.<anonymous> (local-cli/core/__tests__/android/getDependencyConfig.spec.js:23:19)

cc @rafeca