cross-ci/lib/var/BUILD_URL.js

`cross-ci` standardizes environment variables for CI. For example, your can simply use `BUILD_BRANCH` variable in all CI runners instead of `CIRCLE_BRANCH` in CircleCI or `TRAVIS_PULL_REQUEST_BRANCH` in Travis.

const envCi = require('../envCi');

/// URL to CI build page.
const BUILD_URL = ({CI_PLATFORM, PROJECT_OWNER, PROJECT_NAME}) =>
    process.env.CIRCLE_BUILD_URL
    || (CI_PLATFORM === 'travis'
        ? `https://travis-ci.org/${PROJECT_OWNER}/${PROJECT_NAME}/builds/${process.env.TRAVIS_BUILD_ID}`
        : '')
    || (CI_PLATFORM === 'gitlab'
        ? `https://gitlab.com/${PROJECT_OWNER}/${PROJECT_NAME}/-/jobs/${process.env.CI_JOB_ID}`
        : '')
    || envCi.buildUrl
    || '';

module.exports = BUILD_URL;