V4P4: feat(buildpack): scaffolding creation

[zetlen]

Description

Scaffolding tools to create new projects that use PWA Studio as a framework.

Closes #1693.

• 🚨 ⚠️ UPDATE 2019-08-30 ⚠️ 🚨 I have merged [WIP] V4P5: feat(buildpack): Create CLI wizard to make getting started easier #1501 into this PR to make its business value clearer, and to reduce our overhead of workflow. It's only a bit more code, and it becomes much easier to test.

New features

• A create-project subcommand in the buildpack CLI.
• A new package, @magento/create-pwa, that launches an interactive questionnaire as a more friendly interface to buildpack create-project and its many arguments. 🎉 This project's name begins with create, so any NPM user can start a new project with npm init @magento/pwa or yarn create @magento/pwa.
• A structure and API for creating your own templates to use for scaffolding, using the new convention of a _buildpack directory in your project root.

Notes

• Currently only venia-concept is tested and supported. The system is built so that it'll be easy in the future to expand this to using any NPM package.
• Experiment: This introduces the first use of the _buildpack directory, which should contain helper modules and utilities for manipulating PWA Studio code. The _buildpack/create.js is used to generate a visitor for buildpack to use when copying the directory over. Implementing _buildpack/create.js in a repository makes it "shareable"; the dev is responsible for writing any custom code in that module which would ease the transitions.

Verification Steps

buildpack create-project Verification Steps

1. Use a clean install from the repository.
2. Set the environment variable DEBUG_PROJECT_CREATION=1. This is required for it to work in the core repository.
3. Run the following command:

 DEBUG_PROJECT_CREATION=1 ./pwa-studio/packages/pwa-buildpack/bin/buildpack create-project mytest --template "venia-concept" --name "mytestName" --author "zetlen <jzetlen@adobe.com>" --backend-url "https://release-dev-231-npzdaky-zddsyhrdimyra.us-4.magentosite.cloud/" --npm-client "yarn" && cd mytest && yarn watch

4. Observe the creation of a brand new project.

npm init @magento/pwa Verification Steps

An NPM package whose name begins with create- (disregarding @scope) can be used as a project generator. It is expected to expose one CLI command that will be run when a developer runs npm init <package_name_minus_create_prefix>.

Our initializer is called @magento/create-pwa, so the command to use it in NPM is:

 DEBUG_PROJECT_CREATION=1 npm init @magento/pwa

Or in Yarn:

 DEBUG_PROJECT_CREATION=1 yarn create @magento/pwa

ℹ️ Warning: Yarn can't use globally linked modules in its "create", so it's hard to test the Yarn command.

1. From a fresh clone and install of the repo:
2. cd packages/pwa-buildpack
3. yarn link
4. cd ../create-pwa
5. yarn link @magento/pwa-buildpack
6. cd to the root directory
7. Run DEBUG_PROJECT_CREATION=1 npm init @magento/pwa and answer the questions

Expected Result: Jubilance and pride.

Proposed Labels for Change Type/Package

• major (e.g x.0.0 - a breaking change)
• minor (e.g 0.x.0 - a backwards compatible addition)
• patch (e.g 0.0.x - a bug fix)

Checklist:

• I have updated the documentation accordingly, if necessary.
• I have added tests to cover my changes, if necessary.

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[coveralls]

Coverage decreased (-1.7%) to 74.513% when pulling 78713a2 on zetlen/v4api/p4-scaffolding-generator into bdec035 on zetlen/v4api/p3-move-venia-components-to-lib.

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[Jordaneisenburger]

2. cd packages/pwa-buildback

The pwa-buildBack typo got me for a second there, I should stop with the copy pasting habit

[zetlen]

@Jordaneisenburger Whoops! Corrected.