feat: Implement CustomLogger class

.eslintrc.cjs

@@ -28,7 +28,7 @@ module.exports = {
         format: ['camelCase', 'PascalCase', 'UPPER_CASE'],
         leadingUnderscore: 'allow',
       },
-      { selector: 'property', format: ['camelCase', 'UPPER_CASE'], leadingUnderscore: 'allow' },
+      { selector: 'property', format: ['camelCase', 'PascalCase', 'UPPER_CASE'], leadingUnderscore: 'allow' },
       { selector: 'property', modifiers: ['requiresQuotes'], format: null },
       { selector: 'method', format: ['camelCase'], leadingUnderscore: 'allow' },
       { selector: 'function', format: ['camelCase', 'PascalCase'] },

packages/nest-utils/src/logging/custom.logger.test.ts

@@ -0,0 +1,38 @@
+import { TestAppLogger } from '../testing/logging';
+import { ApplicationLogLevel, CustomLogger } from './custom.logger';
+
+describe('CustomLogger', () => {
+  it('should be ok', () => {
+    const logger = new CustomLogger();
+    expect(logger).toBeDefined();
+    expect(logger).toBeInstanceOf(CustomLogger);
+  });
+
+  describe('ApplicationLogLevel', () => {
+    it('should log the expected amount of messages with default logging enabled', () => {
+      const logger = new TestAppLogger({
+        logLevel: ApplicationLogLevel.Default,
+      });
+      logger.debug('hello world');
+      logger.verbose('hello world');
+      logger.log('hello world');
+      logger.warn('hello world');
+      logger.error('hello world');
+      logger.fatal('hello world');
+      expect(logger.printMessages).toHaveBeenCalledTimes(4);
+    });
+
+    it('should log the expected amount of messages with verbose logging enabled', () => {
+      const logger = new TestAppLogger({
+        logLevel: ApplicationLogLevel.Verbose,
+      });
+      logger.debug('hello world');
+      logger.verbose('hello world');
+      logger.log('hello world');
+      logger.warn('hello world');
+      logger.error('hello world');
+      logger.fatal('hello world');
+      expect(logger.printMessages).toHaveBeenCalledTimes(6);
+    });
+  });
+});

packages/nest-utils/src/logging/custom.logger.ts

@@ -0,0 +1,34 @@
+import { ConsoleLogger } from '@nestjs/common';
+
+/**
+ * The application log level.
+ */
+export const ApplicationLogLevel = {
+  Default: 'default',
+  Verbose: 'verbose',
+} as const;
+export type ApplicationLogLevel = (typeof ApplicationLogLevel)[keyof typeof ApplicationLogLevel];
+
+/**
+ * The custom application logger. This logger extends the NestJS console logger, but
+ * simplifies the API to set the application's log levels.
+ * @example
+ * // main.ts
+ * const app = await NestFactory.create(AppModule, {
+ *   logger: new CustomLogger({ logLevel: ApplicationLogLevel.Verbose }),
+ * });
+ */
+export class CustomLogger extends ConsoleLogger {
+  constructor(options?: { logLevel?: ApplicationLogLevel; context?: string }) {
+    super();
+    const { logLevel, context } = { logLevel: 'default', ...options };
+    if (logLevel === ApplicationLogLevel.Verbose) {
+      this.setLogLevels(['debug', 'verbose', 'log', 'warn', 'error', 'fatal']);
+    } else {
+      this.setLogLevels(['log', 'warn', 'error', 'fatal']);
+    }
+    if (context) {
+      this.setContext(context);
+    }
+  }
+}

packages/nest-utils/src/logging/index.ts

@@ -0,0 +1 @@
+export * from './custom.logger';

packages/nest-utils/src/main.ts

@@ -3,6 +3,7 @@
 // Otherwise, they will not be included into the bundle.
 // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 export * from './env';
+export * from './logging';
 export * from './transformers';
 
 // As long as NestJS does not support TypeScript's newer resolution algorithms like 'Node16',

packages/nest-utils/src/testing.ts

@@ -4,3 +4,4 @@
 // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 export * from './testing/container';
 export * from './testing/supertest';
+export * from './testing/logging';

packages/nest-utils/src/testing/logging/index.ts

@@ -0,0 +1 @@
+export * from './test.logger';

packages/nest-utils/src/testing/logging/test.logger.ts

@@ -0,0 +1,19 @@
+import { CustomLogger } from '../../logging/custom.logger';
+
+/**
+ * A custom logger for testing purposes. Replaces `printMessages` with a mocked function
+ * that can be spied on.
+ * @example
+ * const logger = new TestAppLogger();
+ * logger.debug('hello world');
+ * expect(logger.printMessages).toHaveBeenCalledTimes(1);
+ *
+ * // Or hand it over to TestContainer
+ * const container = await TestContainer.create({
+ *   logger,
+ *   // ...
+ * });
+ */
+export class TestAppLogger extends CustomLogger {
+  printMessages = vitest.fn();
+}