feat(logger): add Logger Feature Service (#413)

packages/logger/.size-limit.js

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+// @ts-check
+
+module.exports = [
+  {
+    path: 'lib/cjs/index.js',
+    limit: '1 KB'
+  }
+];

packages/logger/README.md

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+# @feature-hub/logger
+
+[![Package Version][package-badge]][package-npm]
+[![Website][website-badge]][website] [![API][api-badge]][api]
+
+A Feature Service for providing a common logging integration to all Feature Hub
+consumers.
+
+## Installation
+
+### Using Yarn
+
+```sh
+yarn add @feature-hub/logger
+```
+
+### Using NPM
+
+```sh
+npm install @feature-hub/logger
+```
+
+---
+
+Copyright (c) 2019 SinnerSchrader Deutschland GmbH. Released under the terms of
+the [MIT License][license].
+
+[api]: https://feature-hub.io/@feature-hub/logger/
+[api-badge]:
+  https://img.shields.io/badge/API-%40feature--hub%2Flogger-%23ea3458.svg
+[license]: https://github.com/sinnerschrader/feature-hub/blob/master/LICENSE
+[package-badge]: https://img.shields.io/npm/v/@feature-hub/logger.svg
+[package-npm]: https://www.npmjs.com/package/@feature-hub/logger
+[website]: https://feature-hub.io/
+[website-badge]:
+  https://img.shields.io/badge/Website-feature--hub.io-%23500dc5.svg

packages/logger/package.json

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+{
+  "name": "@feature-hub/logger",
+  "version": "0.0.0",
+  "description": "A Feature Service for providing a common logging integration to all Feature Hub consumers.",
+  "homepage": "https://feature-hub.io/",
+  "bugs": {
+    "url": "https://github.com/sinnerschrader/feature-hub/issues"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/sinnerschrader/feature-hub.git"
+  },
+  "license": "MIT",
+  "author": "SinnerSchrader Deutschland GmbH",
+  "files": [
+    "lib",
+    "!__tests__"
+  ],
+  "sideEffects": false,
+  "main": "lib/cjs/index.js",
+  "module": "lib/esm/index.js",
+  "typings": "lib/cjs/index.d.ts",
+  "dependencies": {
+    "@feature-hub/core": "^1.1.0"
+  },
+  "publishConfig": {
+    "access": "public"
+  }
+}

packages/logger/src/__tests__/index.test.ts

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+// tslint:disable:no-implicit-dependencies
+
+import {
+  FeatureServiceEnvironment,
+  FeatureServiceProviderDefinition
+} from '@feature-hub/core';
+import {Stub, Stubbed, stubMethods} from 'jest-stub-methods';
+import {Logger, SharedLogger, defineLogger} from '..';
+
+describe('defineLogger', () => {
+  let mockEnv: FeatureServiceEnvironment<undefined, {}>;
+
+  let loggerDefinition: FeatureServiceProviderDefinition<SharedLogger>;
+
+  beforeEach(() => {
+    mockEnv = {config: undefined, featureServices: {}};
+    loggerDefinition = defineLogger();
+  });
+
+  it('creates a Logger definition', () => {
+    expect(loggerDefinition.id).toBe('s2:logger');
+    expect(loggerDefinition.dependencies).toBeUndefined();
+  });
+
+  describe('#create', () => {
+    it('creates a shared Feature Service containing version 1.0.0', () => {
+      const sharedLogger = loggerDefinition.create(mockEnv);
+
+      expect(sharedLogger['1.0.0']).toBeDefined();
+    });
+  });
+
+  describe('Logger', () => {
+    let logger: Logger;
+
+    describe('with the default createConsumerLogger function', () => {
+      let stubbedConsole: Stubbed<Console>;
+
+      beforeEach(() => {
+        stubbedConsole = stubMethods(console);
+
+        logger = loggerDefinition.create(mockEnv)['1.0.0']('test:id')
+          .featureService;
+      });
+
+      afterEach(() => {
+        stubbedConsole.restore();
+      });
+
+      const loggerMethods: (keyof Logger)[] = [
+        'trace',
+        'debug',
+        'info',
+        'warn',
+        'error'
+      ];
+
+      for (const method of loggerMethods) {
+        describe(`#${method}`, () => {
+          it(`delegates to console.${method}`, () => {
+            logger[method]('test');
+
+            expect(stubbedConsole.stub[method].mock.calls).toEqual([['test']]);
+          });
+
+          it('preserves the call stack', () => {
+            stubbedConsole.stub[method].mockImplementationOnce(() => {
+              throw new Error(`mock error for ${method}}`);
+            });
+
+            expect.assertions(2);
+
+            try {
+              logger[method]('test');
+            } catch (error) {
+              expect(error.stack).toMatch(
+                /logger\/src\/__tests__\/index.test\.(js|ts)/
+              );
+
+              expect(error.stack).not.toMatch(/logger\/src\/index\.(js|ts)/);
+            }
+          });
+        });
+      }
+    });
+
+    describe('with a custom createConsumerLogger function', () => {
+      let mockConsumerLogger: Stub<Logger>;
+      let mockCreateConsumerLogger: jest.Mock<Stub<Logger>>;
+
+      beforeEach(() => {
+        mockConsumerLogger = {
+          trace: jest.fn(),
+          debug: jest.fn(),
+          info: jest.fn(),
+          warn: jest.fn(),
+          error: jest.fn()
+        };
+
+        mockCreateConsumerLogger = jest.fn(() => mockConsumerLogger);
+
+        loggerDefinition = defineLogger(mockCreateConsumerLogger);
+
+        logger = loggerDefinition.create(mockEnv)['1.0.0']('test:id')
+          .featureService;
+      });
+
+      it('calls the given createConsumerLogger with the consumerUid', () => {
+        expect(mockCreateConsumerLogger.mock.calls).toEqual([['test:id']]);
+      });
+
+      it('uses the defined consumer logger as Feature Service', () => {
+        expect(logger).toBe(mockConsumerLogger);
+      });
+    });
+  });
+});

packages/logger/src/index.ts

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+import {
+  FeatureServiceBinder,
+  FeatureServiceProviderDefinition,
+  Logger,
+  SharedFeatureService
+} from '@feature-hub/core';
+
+export {Logger} from '@feature-hub/core';
+
+export interface SharedLogger extends SharedFeatureService {
+  readonly '1.0.0': FeatureServiceBinder<Logger>;
+}
+
+export type ConsumerLoggerCreator = (consumerUid: string) => Logger;
+
+export function defineLogger(
+  createConsumerLogger: ConsumerLoggerCreator = () => console
+): FeatureServiceProviderDefinition<SharedLogger> {
+  return {
+    id: 's2:logger',
+
+    create: () => ({
+      '1.0.0': consumerUid => ({
+        featureService: createConsumerLogger(consumerUid)
+      })
+    })
+  };
+}

packages/logger/tsconfig.cjs.json

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+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "paths": {},
+    "outDir": "lib/cjs",
+    "rootDir": "src"
+  }
+}

packages/logger/tsconfig.esm.json

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+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "module": "esnext",
+    "paths": {},
+    "outDir": "lib/esm",
+    "rootDir": "src"
+  }
+}

packages/logger/tsconfig.json

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+{
+  "extends": "../../tsconfig.json",
+  "include": ["src/**/*"]
+}

packages/logger/tslint.json

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+{
+  "extends": "../../tslint.json"
+}