feat(logger): adding basic crude logger module, and support for log levels by passed param/env param

Author: Alan Churley

packages/logging/src/greeter/index.ts

@@ -1 +1,50 @@
-export * from './greeter';
+enum LogLevel {
+    DEBUG = 1,
+    INFO = 2,
+    WARNING = 3,
+    ERROR = 4,
+    CRITICAL = 5
+}
+
+interface LoggerConfig {
+    LogLevel?: LogLevel;
+}
+
+class Logger {
+    private CURRENT_LOG_LEVEL: LogLevel = LogLevel.INFO;
+
+    constructor(config?: LoggerConfig) {
+        config = config || {};
+        this.setInitialLogLevel(config);
+    }
+    private setInitialLogLevel(config: LoggerConfig) {
+
+        if (config.LogLevel) {
+            this.CURRENT_LOG_LEVEL = config.LogLevel;
+            return;
+        }
+        if (process.env.LOG_LEVEL) {
+            const environmentVariableLevel = process.env.LOG_LEVEL;
+            if (environmentVariableLevel in LogLevel) {
+                this.CURRENT_LOG_LEVEL = LogLevel[environmentVariableLevel as keyof typeof LogLevel];
+                return;
+            }
+            this.Warn(`LOG_LEVEL environment value was not valid, 
+            Received ${environmentVariableLevel} and expected one of ${Object.keys(LogLevel).join(', ')}`);
+        }
+    }
+    getCurrentLogLevel() {
+        return this.CURRENT_LOG_LEVEL;
+    }
+    public Warn(message?: string) {
+        //ToDo - change once logging has been established
+    }
+}
+
+export {
+    Logger,
+    LogLevel
+};
+
+
+

packages/logging/src/index.ts

@@ -0,0 +1,43 @@
+import {Logger, LogLevel} from '../../src';
+
+describe('Logger Class', () => {
+    test('Should return a valid instance', () => {
+        const logger = new Logger();
+    });
+    describe('Instantiation Log levels', () => {
+        afterEach(() => {
+            delete process.env.LOG_LEVEL;
+        })
+        test('Should default to INFO if no level passed', () =>{
+            const logger = new Logger();
+            expect(logger.getCurrentLogLevel()).toBe(LogLevel.INFO);
+        })
+        test('Log level passed in constructor should be maintained', () => {
+            const loggerDEBUG = new Logger({LogLevel: LogLevel.DEBUG});
+            expect(loggerDEBUG.getCurrentLogLevel()).toBe(LogLevel.DEBUG);
+            const loggerWARN = new Logger({LogLevel: LogLevel.WARNING});
+            expect(loggerWARN.getCurrentLogLevel()).toBe(LogLevel.WARNING);
+            const loggerCRITICAL = new Logger({LogLevel: 5});
+            expect(loggerCRITICAL.getCurrentLogLevel()).toBe(LogLevel.CRITICAL);
+        })
+        test('Log level passed as ENV var should be set', () => {
+            process.env.LOG_LEVEL = "ERROR";
+            const logger = new Logger();
+            expect(logger.getCurrentLogLevel()).toBe(LogLevel.ERROR);
+        })
+        test('Log level passed in constructor should override environment variable', () => {
+            process.env.LOG_LEVEL = "ERROR";
+            const logger = new Logger({LogLevel: LogLevel.CRITICAL});
+            expect(logger.getCurrentLogLevel()).toBe(LogLevel.CRITICAL);
+            process.env.LOG_LEVEL = "DEBUG";
+            const loggerDEBUG = new Logger();
+            expect(loggerDEBUG.getCurrentLogLevel()).toBe(LogLevel.DEBUG);
+        })
+        test('Invalid ENV param should throw warning, and set log level to INFO', () => {
+            process.env.LOG_LEVEL = "ALERT";
+            const logger = new Logger();
+            expect(logger.getCurrentLogLevel()).toBe(LogLevel.INFO);
+        })
+    })
+});
+