fix: add test logger (#365)

src/index.js

@@ -20,4 +20,5 @@ module.exports = {
   ...require('./coralogix'),
   ...require('./bunyan'),
   ...require('./secret'),
+  ...require('./testing'),
 };

src/testing.js

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2020 Adobe. All rights reserved.
+ * This file is licensed to you under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License. You may obtain a copy
+ * of the License at http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under
+ * the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS
+ * OF ANY KIND, either express or implied. See the License for the specific language
+ * governing permissions and limitations under the License.
+ */
+const { MemLogger, serializeMessage, SimpleInterface } = require('./log');
+
+const ANSI_REGEXP = RegExp([
+  '[\\u001B\\u009B][[\\]()#;?]*(?:(?:(?:[a-zA-Z\\d]*(?:;[a-zA-Z\\d]*)*)?\\u0007)',
+  '(?:(?:\\d{1,4}(?:;\\d{0,4})*)?[\\dA-PRZcf-ntqry=><~]))',
+].join('|'), 'g');
+
+/**
+ * Creates a test logger that logs to the console but also to an internal buffer. The contents of
+ * the buffer can be retrieved with {@code Logger#getOutput()} which will flush also close the
+ * logger. Each test logger will be registered with a unique category, so that there is no risk of
+ * reusing a logger in between tests.
+ * @params {object} config logger config
+ * @params {string} [config.level='debug'] log level
+ * @params {bool} [config.keepANSI=false] enable to keep ANSI characters in string
+ * @returns {SimpleInterface}
+ */
+function createTestLogger(config = {}) {
+  const memLogger = new MemLogger({
+    level: 'silly',
+  });
+
+  const plainMessage = (msg) => serializeMessage(msg.message);
+  const stripMessage = (msg) => serializeMessage(msg.message).replace(ANSI_REGEXP, '');
+  const msgFormat = config.keepANSI ? plainMessage : stripMessage;
+
+  const testLogger = new SimpleInterface({
+    level: config.level || 'debug',
+    logger: memLogger,
+  });
+
+  return new Proxy(testLogger, {
+    get(target, prop) {
+      if (prop === 'getOutput') {
+        return () => `${memLogger.buf.map((msg) => `${msg.level}: ${msgFormat(msg)}`).join('\n')}\n`;
+      }
+      return target[prop];
+    },
+  });
+}
+
+module.exports = {
+  createTestLogger,
+};

test/testing.test.js

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2024 Adobe. All rights reserved.
+ * This file is licensed to you under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License. You may obtain a copy
+ * of the License at http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under
+ * the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS
+ * OF ANY KIND, either express or implied. See the License for the specific language
+ * governing permissions and limitations under the License.
+ */
+
+/* eslint-env mocha */
+const assert = require('assert');
+const { createTestLogger } = require('../src/index');
+
+describe('Test Logger', () => {
+  it('Creates test logger and produces output', () => {
+    const logger = createTestLogger();
+    logger.info('Hello, world.');
+    assert.strictEqual(logger.getOutput(), 'info: Hello, world.\n');
+  });
+});