Document how to build for all platforms on Travis

• Version: 19.8.0
• Target: macOS, Linux, Windows

Version 19.6.0 introduced support for building Windows target on macOS. It’s awesome that I can drop AppVeyor, but would be nice if it was documented how to set this up on Travis.

For example, can I do electron-builder -mwl in a dist npm run script and will electron-builder ignore building the Windows and macOS apps when running in the Linux image on Travis and ignore building the Linux app on the macOS image on Travis, or do I need a complicated .travis.yml?

Would be nice if electron-builder had a simple mode for this. I can imagine this would be the most common use-case.

[develar]

osx_image: xcode8.3

dist: trusty
sudo: false

language: node_js
node_js: "8"

env:
  global:
    - ELECTRON_CACHE=$HOME/.cache/electron
    - ELECTRON_BUILDER_CACHE=$HOME/.cache/electron-builder

os:
  - linux
  - osx

cache:
  directories:
  - node_modules
  - $HOME/.cache/electron
  - $HOME/.cache/electron-builder
  - $HOME/.npm/_prebuilds

before_install:
  - mkdir -p /tmp/git-lfs && curl -L https://github.com/github/git-lfs/releases/download/v2.2.0/git-lfs-$([ "$TRAVIS_OS_NAME" == "linux" ] && echo "linux" || echo "darwin")-amd64-2.2.0.tar.gz | tar -xz -C /tmp/git-lfs --strip-components 1 && /tmp/git-lfs/git-lfs pull
  - curl -L https://yarnpkg.com/latest.tar.gz | tar xvz && mv dist $HOME/.yarn
  - export PATH="$HOME/.yarn/bin:$PATH"

install:
  - yarn

script:
  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then yarn release; fi
  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then yarn release -- --mac --win; fi

before_cache:
  - rm -rf $HOME/.cache/electron-builder/wine

branches:
  except:
    - "/^v\\d+\\.\\d+\\.\\d+$/"

where release script in your package.json something like yarn compile && electron-builder.

[develar]

Example will be provided as soon as I will create prebuilt for keytar 😃