# Permission System 2.0
## Background
This PR migrates the extension permission system to [the new `PermissionController`](https://github.com/MetaMask/snaps-skunkworks/tree/main/packages/controllers/src/permissions).
The original permission system, based on [`rpc-cap`](https://github.com/MetaMask/rpc-cap), introduced [`ZCAP-LD`](https://w3c-ccg.github.io/zcap-ld/)-like permissions to our JSON-RPC stack.
We used it to [implement](https://github.com/MetaMask/metamask-extension/pull/7004) what we called "LoginPerSite" in [version 7.7.0](https://github.com/MetaMask/metamask-extension/releases/tag/v7.7.0) of the extension, which enabled the user to choose which accounts, if any, should be exposed to each dapp.
While that was a worthwhile feature in and of itself, we wanted a permission _system_ in order to enable everything we are going to with Snaps.
Unfortunately, the original permission system was difficult to use, and necessitated the creation of the original `PermissionsController` (note the "s"), which was more or less a wrapper for `rpc-cap`.
With this PR, we shake off the yoke of the original permission system, in favor of the modular, self-contained, ergonomic, and more mature permission system 2.0.
Note that [the `PermissionController` readme](https://github.com/MetaMask/snaps-skunkworks/tree/main/packages/controllers/src/permissions/README.md) explains how the new permission system works.
The `PermissionController` and `SubjectMetadataController` are currently shipped via `@metamask/snap-controllers`. This is a temporary state of affairs, and we'll move them to `@metamask/controllers` once they've landed in prod.
## Changes in Detail
First, the changes in this PR are not as big as they seem. Roughly half of the additions in this PR are fixtures in the test for the new migration (number 68), and a significant portion of the remaining ~2500 lines are due to find-and-replace changes in other test fixtures and UI files.
- The extension `PermissionsController` has been deleted, and completely replaced with the new `PermissionController` from [`@metamask/snap-controllers`](https://www.npmjs.com/package/@metamask/snap-controllers).
- The original `PermissionsController` "domain metadata" functionality is now managed by the new `SubjectMetadataController`, also from [`@metamask/snap-controllers`](https://www.npmjs.com/package/@metamask/snap-controllers).
- The permission activity and history log controller has been renamed `PermissionLogController` and has its own top-level state key, but is otherwise functionally equivalent to the existing implementation.
- Migration number 68 has been added to account for the new state changes.
- The tests in `app/scripts/controllers/permissions` have been migrated from `mocha` to `jest`.
Reviewers should focus their attention on the following files:
- `app/scripts/`
- `metamask-controller.js`
- This is where most of the integration work for the new `PermissionController` occurs.
Some functions that were internal to the original controller were moved here.
- `controllers/permissions/`
- `selectors.js`
- These selectors are for `ControllerMessenger` selector subscriptions. The actual subscriptions occur in `metamask-controller.js`. See the `ControllerMessenger` implementation for details.
- `specifications.js`
- The caveat and permission specifications are required by the new `PermissionController`, and are used to specify the `eth_accounts` permission and its JSON-RPC method implementation.
See the `PermissionController` readme for details.
- `migrations/068.js`
- The new state should be cross-referenced with the controllers that manage it.
The accompanying tests should also be thoroughly reviewed.
Some files may appear new but have just moved and/or been renamed:
- `app/scripts/lib/rpc-method-middleware/handlers/request-accounts.js`
- This was previously implemented in `controllers/permissions/permissionsMethodMiddleware.js`.
- `test/mocks/permissions.js`
- A truncated version of `test/mocks/permission-controller.js`.
Co-authored-by: Mark Stacey <markjstacey@gmail.com>
The extension version used throughout the wallet is now normalized to a
SemVer-compliant version that matches the version used in
`package.json`. We use this version for display on the "About" page,
and we attach it to all error reports and metric events, so it's
important that we format it consistently so that we can correlate
events on the same version across different browsers.
This normalization step is necessary because Firefox and Chrome both
have different requirements for the extension version, and neither is
SemVer-compliant.
The npm scripts used to run Mocha scripts have been greatly simplified.
As we transition more tests from Mocha to Jest it was becoming
increasingly difficult to update the CLI arguments to keep all of these
scripts working correctly. This reorganization should make that process
much simpler.
The base Mocha options are in `.mocharc.js` - all except for the target
tests to run. Those are still given via the CLI. There is a second
config file specifically for the `test:unit:lax` tests (i.e. the Mocha
tests that have no coverage requirements) because it requires a change
to the `ignored` configuration property. We can create an additional
configuration file for each test script we add that needs further
configuration changes.
The `test:unit:path` script used to be used to run Mocha tests at a
given path. Now that can be done using `yarn mocha` instead, so this
script has been removed.
The `yarn watch` command has been broken for some time now, so it has
been removed as well. Mocha tests can still be run with a file watcher
using `yarn mocha --watch <path>` or `yarn test:unit:mocha --watch`.
The README has been updated to remove references about the `watch`
command that was removed. I considered explaining the other test
scripts there as well, but they were difficult to explain I will
attempt to update the README after making further simplifications
instead.
