Fixes#2876 with @paulmelnikow's suggestion
Moved imports of `ServiceTester` and `createServiceTester` to a separate file so that dev dependencies are not imported by service classes.
Continue to implement #2698:
- Add `core/base-service/index.js` (but hold off on moving the things it imports)
- Add shortcuts in `services/index.js` for Base*Service, errors, and deprecatedService. This file will be streamlined later to avoid cluttering it with rarely used bits.
- Apply consistent ordering of imports and use of `module.exports` in testers.
- Remove some renaming of imports.
- Remove obsolete tests here and there.
Three main goals:
1. In the front end:
a. Show form fields and automatically assemble badge URLs (#701)
c. Group together examples for the same service
b. Show deprecated services
2. Make it easy to changing the schema of `examples`, thanks to 100% validation. One challenge with frameworks is that when there are typos things fail silently which is pretty unfriendly to developers. The validation should really help with that. (This caught one bug in AUR, though I fixed it in #2405 which landed first.)
3. Produce a service definition export for external tool builders. (#776)
4. Build toward harmony between the front-end data structure and the `examples` key in the service classes. I aliased `staticPreview` to `staticExample` which starts this process.
The old format:
- Lacked a consistent machine-readable representation of the fields.
- Flattened multiple examples for the same service were flattened.
- Excluded deprecated services.
The new format improves a few things, too:
- It cleans up the naming. Since this file evolved over time, the names were a bit muddled (i.e. what was an example vs a preview).
- It duplicated information (like `.svg`). (I can imagine dropping the `.svg` from our badge URLs someday, which would make the URLs easier to read and maintain.)
- For a human reading the YAML file, providing the static example as a deconstructed object is more readable.
Here are a couple snippets:
```yml
- category: build
name: AppVeyorCi
isDeprecated: false
route:
format: '([^/]+/[^/]+)(?:/(.+))?'
queryParams: []
examples:
- title: AppVeyor
example: {path: /appveyor/ci/gruntjs/grunt, queryParams: {}}
preview: {label: build, message: passing, color: brightgreen}
keywords: []
- title: AppVeyor branch
example: {path: /appveyor/ci/gruntjs/grunt/master, queryParams: {}}
preview: {label: build, message: passing, color: brightgreen}
keywords: []
- category: downloads
name: AmoDownloads
isDeprecated: false
examples:
- title: Mozilla Add-on
example: {path: /amo/d/dustman, queryParams: {}}
preview: {path: /amo/d/dustman, queryParams: {}}
keywords: [amo, firefox]
```
I've rewritten the deprecated services using the `deprecatedService` helper from #1922. I added a test for `Deprecated`, and for `enforceDeprecation`, which isn't being used right now, but is there for future use.
This also makes it possible to write services using BaseService which do not have any named parameters (with a test).
Ref: #1358
