Improve GitHub actions duration

[Neylix]

Description

Improve caching datas in Github Actions to reduce test time, add MIX_ENV=test to compile code once (previously code was compiled two times), update some test files to not set the state name to avoid test error (state already started).

Fixes #302

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Runned Github actions on a test branch, the result is a test time 3x faster :
Before :

After :

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[ghost]

Good, I think we can improve it by caching the _build to avoid the recompilation of everything for each job run

[ghost]

Good, I think we can improve it by caching the _build to avoid the recompilation of everything for each job run

Something like this maybe:

  - name: Restore build cache
        uses: actions/cache@v2
        with:
          path: _build
          key: ${{ runner.os }}-build-${{ hashFiles('mix.lock') }}-myapp
          restore-keys: ${{ runner.os }}-build-myapp
          ```

[Neylix]

Exact ! It reduces the time by 1 min !