From b0671031f1bb2323cf057c0a9c6495d4fa1cc782 Mon Sep 17 00:00:00 2001
From: Ruben Taelman <ruben.taelman@ugent.be>
Date: Tue, 22 Sep 2020 11:28:05 +0200
Subject: [PATCH] feat: add void logger

---
 src/logging/VoidLogger.ts                   | 13 +++++++++++++
 src/logging/VoidLoggerFactory.ts            | 15 +++++++++++++++
 test/unit/logging/VoidLogger.test.ts        | 12 ++++++++++++
 test/unit/logging/VoidLoggerFactory.test.ts | 14 ++++++++++++++
 4 files changed, 54 insertions(+)
 create mode 100644 src/logging/VoidLogger.ts
 create mode 100644 src/logging/VoidLoggerFactory.ts
 create mode 100644 test/unit/logging/VoidLogger.test.ts
 create mode 100644 test/unit/logging/VoidLoggerFactory.test.ts

diff --git a/src/logging/VoidLogger.ts b/src/logging/VoidLogger.ts
new file mode 100644
index 000000000..e154ab801
--- /dev/null
+++ b/src/logging/VoidLogger.ts
@@ -0,0 +1,13 @@
+import type { Logger } from './Logger';
+import type { LogLevel } from './LogLevel';
+
+/**
+ * A logger that does nothing on a log message.
+ */
+export class VoidLogger implements Logger {
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
+  public log(level: LogLevel, message: string, meta?: any): Logger {
+    // Do nothing
+    return this;
+  }
+}
diff --git a/src/logging/VoidLoggerFactory.ts b/src/logging/VoidLoggerFactory.ts
new file mode 100644
index 000000000..d596bbbb0
--- /dev/null
+++ b/src/logging/VoidLoggerFactory.ts
@@ -0,0 +1,15 @@
+import type { Logger } from './Logger';
+import type { LoggerFactory } from './LoggerFactory';
+import { VoidLogger } from './VoidLogger';
+
+/**
+ * A factory that always returns {@link VoidLogger}, which does nothing on log messages.
+ */
+export class VoidLoggerFactory implements LoggerFactory {
+  private readonly logger = new VoidLogger();
+
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
+  public createLogger(label: string): Logger {
+    return this.logger;
+  }
+}
diff --git a/test/unit/logging/VoidLogger.test.ts b/test/unit/logging/VoidLogger.test.ts
new file mode 100644
index 000000000..b1058b5eb
--- /dev/null
+++ b/test/unit/logging/VoidLogger.test.ts
@@ -0,0 +1,12 @@
+import { VoidLogger } from '../../../src/logging/VoidLogger';
+
+describe('VoidLogger', (): void => {
+  let logger: VoidLogger;
+  beforeEach(async(): Promise<void> => {
+    logger = new VoidLogger();
+  });
+
+  it('does nothing when log is invoked.', async(): Promise<void> => {
+    expect(logger.log('debug', 'my message', { abc: true })).toBe(logger);
+  });
+});
diff --git a/test/unit/logging/VoidLoggerFactory.test.ts b/test/unit/logging/VoidLoggerFactory.test.ts
new file mode 100644
index 000000000..f46a57780
--- /dev/null
+++ b/test/unit/logging/VoidLoggerFactory.test.ts
@@ -0,0 +1,14 @@
+import { VoidLogger } from '../../../src/logging/VoidLogger';
+import { VoidLoggerFactory } from '../../../src/logging/VoidLoggerFactory';
+
+describe('VoidLoggerFactory', (): void => {
+  let factory: VoidLoggerFactory;
+  beforeEach(async(): Promise<void> => {
+    factory = new VoidLoggerFactory();
+  });
+
+  it('creates VoidLoggers.', async(): Promise<void> => {
+    const logger = factory.createLogger('MyLabel');
+    expect(logger).toBeInstanceOf(VoidLogger);
+  });
+});