Add travis CI script

[am11]

Uses dotnet-cli v1.0.0-rc4-004771 without mono to specifically
build netstandard1.6 TFM.

Progress towards #14.

[am11]

@felschr, in my fork, current the build succeeds but the job fails at the step where it tries to push the tag: https://travis-ci.org/am11/AspNetCore.Identity.DocumentDB/builds/207810945#L554.
Shouldn't it be the other way around? Like when you will push a release tag, only then the CI job should upload the release assets? Something like: https://docs.travis-ci.com/user/deployment/releases/:

(however, this can be done va AppVeyor only, as the assembly we are producing here is platform agnostic / pure-MSIL)

[felschr]

Could you shortly explain why this Travis CI build would be useful in addition to the AppVeyor build?

The AppVeyor build is already building for net451 and netstandard1.6.

[am11]

Hey @felschr!
I took the .travis.yml from your netcore branch and fixed it for dotnet-cli RC4 and version extraction from csproj. Is that meant to be deprecated / removed?

Usually repos have both AppVeyor and TravisCI configured, to keep ensuring the xplat-ness and step aside related issue before they emerge in public landscape. For instance, unless we re-read the documentation of .NET BCL APIs that we have been using for ages, we never know which API will throw PlatformNotSupportedException on Unix, while developing a cross-platform library on Windows.

In README, I read:

Microsoft.Azure.DocumentDB v1.10.0 - supports net45 (netstandard support is in development)

I am planning to consume this package for the app running on Unix, knowing Azure has released the DocDB package supporting .NET Core. So I cloned your repo and found that you already have the support in master branch.

[felschr]

I see.
The problem is that the Travis CI script isn't running the unit and integration tests, it's just running the build.
As AppVeyor already creates the build we can remove the Git/Github tag/release publishing from the Travis CI completely.

So we should try to find a way to run the tests on Travis CI. Or rather find a way to run the tests on a Linux machine. Am I right?

[am11]

@felschr, I agree that we must be able to run tests. Unfortunately, DocDB emulator is only available on Windows; native Unix support is on their long-term roadmap https://docs.microsoft.com/en-us/azure/documentdb/documentdb-nosql-local-emulator (see comments).

We can use xunit traits to disable the affected tests for non-Windows for now, but there are only few such tests.

[felschr]

Sounds good.
Do you want to create a new pull request for a script that runs the tests (it's ok when it fails initially) and does not create a Git tag or should I create one?

[am11]

@felschr, done. Can you please take a look?

[felschr]

Git tag creation and GitHub release could probably be removed.
Otherwise, it looks good. I'll check the Git/Github behavior later.

[felschr]

Ok, everything looks quite ok.
The build(s) still behave somewhat strange now which could be fixed.

1. The Travis CI master build finished first but failed during the git tag creation with:
   fatal: Authentication failed for 'https://@github.com/FelschR/AspNetCore.Identity.DocumentDB.git/'
2. The AppVeyor master build finished successfully afterward.
3. Then the Travis CI v0.3.0-beta-master-15 (tag) build was (re)triggered and finished successfully.

The 2nd Travis CI build is successful because it skips the git tag creation because the commit was now tagged by AppVeyor.

The question is now:
Should we just remove git/Github tag/release creation in the Travis CI build at all? Or just use Travis as to run the tests in a Linux environment.
I can't think of any reason why it would be crucial.

[am11]

Perhaps it was the first time on the master branch and some Travis<->GitHub syncing failed? Might be the intermittent error?
Should we wait a bit and if this problem persists, then remove the tag?

On a slightly related note, the TravisCI badge in the README has link to netcore branch. Perhaps we can apply the following patch:

- [![Travis CI build status](https://travis-ci.org/FelschR/aspnetcore-identity-documentdb.svg?branch=netcore)](https://travis-ci.org/FelschR/aspnetcore-identity-documentdb?branch=netcore)

+ [![Travis CI build status](https://travis-ci.org/FelschR/aspnetcore-identity-documentdb.svg?branch=netcore)](https://travis-ci.org/FelschR/AspNetCore.Identity.DocumentDB)

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Also, I was thinking to add macOS and Mono (requires separate SLN with old-CSPROJ facade) to the matrix by extracting out the script to a separate .sh file, like what we did here: https://github.com/maxmind/MaxMind-DB-Reader-dotnet/blob/9d247d7/.travis.yml. :)

[felschr]

Just did a build and noticed the same thing again: first build failed with Github error, 2nd went through.
I'll have to look into that later.