Add example controllers

.gitignore

@@ -15,6 +15,9 @@ package-lock.json
 # Build preview message
 preview-build-message.txt
 
+examples/*/coverage
+examples/*/dist
+examples/*/docs
 packages/*/coverage
 packages/*/dist
 packages/*/docs

examples/example-controllers/CHANGELOG.md

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+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+[Unreleased]: https://github.com/MetaMask/core/

examples/example-controllers/LICENSE

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+MIT License
+
+Copyright (c) 2024 MetaMask
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

examples/example-controllers/README.md

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+# `@metamask/example-controllers`
+
+This package is designed to illustrate best practices for controller packages and controller files, including tests.
+
+## Installation
+
+`yarn add @metamask/example-controllers`
+
+or
+
+`npm install @metamask/example-controllers`
+
+## Contributing
+
+This package is part of a monorepo. Instructions for contributing can be found in the [monorepo README](https://github.com/MetaMask/core#readme).

examples/example-controllers/jest.config.js

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+/*
+ * For a detailed explanation regarding each configuration property and type check, visit:
+ * https://jestjs.io/docs/configuration
+ */
+
+const merge = require('deepmerge');
+const path = require('path');
+
+const baseConfig = require('../../jest.config.packages');
+
+const displayName = path.basename(__dirname);
+
+module.exports = merge(baseConfig, {
+  // The display name when running multiple projects
+  displayName,
+
+  // An object that configures minimum threshold enforcement for coverage results
+  coverageThreshold: {
+    global: {
+      branches: 100,
+      functions: 100,
+      lines: 100,
+      statements: 100,
+    },
+  },
+});

examples/example-controllers/package.json

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+{
+  "name": "@metamask/example-controllers",
+  "version": "0.0.0",
+  "private": true,
+  "description": "Fetches gas prices periodically",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/MetaMask/core.git"
+  },
+  "files": [
+    "dist/"
+  ],
+  "scripts": {
+    "build": "tsup --config ../../tsup.config.ts --tsconfig ./tsconfig.build.json --clean",
+    "build:docs": "typedoc",
+    "changelog:validate": "../../scripts/validate-changelog.sh @metamask/example-controllers",
+    "test": "NODE_OPTIONS=--experimental-vm-modules jest --reporters=jest-silent-reporter",
+    "test:clean": "NODE_OPTIONS=--experimental-vm-modules jest --clearCache",
+    "test:verbose": "NODE_OPTIONS=--experimental-vm-modules jest --verbose",
+    "test:watch": "NODE_OPTIONS=--experimental-vm-modules jest --watch"
+  },
+  "dependencies": {
+    "@metamask/base-controller": "^6.0.2",
+    "@metamask/utils": "^9.1.0"
+  },
+  "devDependencies": {
+    "@metamask/auto-changelog": "^3.4.4",
+    "@types/jest": "^27.4.1",
+    "deepmerge": "^4.2.2",
+    "jest": "^27.5.1",
+    "nock": "^13.3.1",
+    "ts-jest": "^27.1.4",
+    "typedoc": "^0.24.8",
+    "typedoc-plugin-missing-exports": "^2.0.0",
+    "typescript": "~5.0.4"
+  },
+  "engines": {
+    "node": "^18.18 || >=20"
+  }
+}

examples/example-controllers/src/gas-prices-controller.test.ts

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+import { ControllerMessenger } from '@metamask/base-controller';
+
+import type {
+  ExtractAvailableAction,
+  ExtractAvailableEvent,
+} from '../tests/helpers';
+import type { GasPricesControllerMessenger } from './gas-prices-controller';
+import { GasPricesController } from './gas-prices-controller';
+import type { AbstractGasPricesService } from './gas-prices-service/abstract-gas-prices-service';
+import {
+  getDefaultNetworkControllerState,
+  type NetworkControllerGetStateAction,
+} from './network-controller-types';
+
+describe('GasPricesController', () => {
+  describe('constructor', () => {
+    it('uses all of the given state properties to initialize state', () => {
+      const gasPricesService = buildGasPricesService();
+      const givenState = {
+        gasPricesByChainId: {
+          '0x1': {
+            low: 10,
+            average: 15,
+            high: 20,
+            fetchedDate: '2024-01-01',
+          },
+        },
+      };
+      const controller = new GasPricesController({
+        messenger: getControllerMessenger(),
+        state: givenState,
+        gasPricesService,
+      });
+
+      expect(controller.state).toStrictEqual(givenState);
+    });
+
+    it('fills in missing state properties with default values', () => {
+      const gasPricesService = buildGasPricesService();
+      const controller = new GasPricesController({
+        messenger: getControllerMessenger(),
+        gasPricesService,
+      });
+
+      expect(controller.state).toMatchInlineSnapshot(`
+        Object {
+          "gasPricesByChainId": Object {},
+        }
+      `);
+    });
+  });
+
+  describe('updateGasPrices', () => {
+    beforeEach(() => {
+      jest.useFakeTimers().setSystemTime(new Date('2024-01-02'));
+    });
+
+    afterEach(() => {
+      jest.useRealTimers();
+    });
+
+    it('fetches gas prices for the current chain through the service object and updates state accordingly', async () => {
+      const gasPricesService = buildGasPricesService();
+      jest.spyOn(gasPricesService, 'fetchGasPrices').mockResolvedValue({
+        low: 5,
+        average: 10,
+        high: 15,
+      });
+      const rootMessenger = getRootControllerMessenger({
+        networkControllerGetStateActionHandler: () => ({
+          ...getDefaultNetworkControllerState(),
+          chainId: '0x42',
+        }),
+      });
+      const controller = new GasPricesController({
+        messenger: getControllerMessenger(rootMessenger),
+        gasPricesService,
+      });
+
+      await controller.updateGasPrices();
+
+      expect(controller.state).toStrictEqual({
+        gasPricesByChainId: {
+          '0x42': {
+            low: 5,
+            average: 10,
+            high: 15,
+            fetchedDate: '2024-01-02T00:00:00.000Z',
+          },
+        },
+      });
+    });
+  });
+});
+
+/**
+ * The union of actions that the root messenger allows.
+ */
+type RootAction = ExtractAvailableAction<GasPricesControllerMessenger>;
+
+/**
+ * The union of events that the root messenger allows.
+ */
+type RootEvent = ExtractAvailableEvent<GasPricesControllerMessenger>;
+
+/**
+ * Constructs the unrestricted messenger. This can be used to call actions and
+ * publish events within the tests for this controller.
+ *
+ * @param args - The arguments to this function.
+ * @param args.networkControllerGetStateActionHandler - Used to mock the
+ * `NetworkController:getState` action on the messenger.
+ * @returns The unrestricted messenger suited for GasPricesController.
+ */
+function getRootControllerMessenger({
+  networkControllerGetStateActionHandler = jest
+    .fn<
+      ReturnType<NetworkControllerGetStateAction['handler']>,
+      Parameters<NetworkControllerGetStateAction['handler']>
+    >()
+    .mockReturnValue(getDefaultNetworkControllerState()),
+}: {
+  networkControllerGetStateActionHandler?: NetworkControllerGetStateAction['handler'];
+} = {}): ControllerMessenger<RootAction, RootEvent> {
+  const rootMessenger = new ControllerMessenger<RootAction, RootEvent>();
+  rootMessenger.registerActionHandler(
+    'NetworkController:getState',
+    networkControllerGetStateActionHandler,
+  );
+  return rootMessenger;
+}
+
+/**
+ * Constructs the messenger which is restricted to relevant GasPricesController
+ * actions and events.
+ *
+ * @param rootMessenger - The root messenger to restrict.
+ * @returns The restricted messenger.
+ */
+function getControllerMessenger(
+  rootMessenger = getRootControllerMessenger(),
+): GasPricesControllerMessenger {
+  return rootMessenger.getRestricted({
+    name: 'GasPricesController',
+    allowedActions: ['NetworkController:getState'],
+    allowedEvents: [],
+  });
+}
+
+/**
+ * Constructs a mock GasPricesService object for use in testing.
+ *
+ * @returns The mock GasPricesService object.
+ */
+function buildGasPricesService(): AbstractGasPricesService {
+  return {
+    fetchGasPrices: jest.fn(),
+  };
+}