debug-js#719 - Support decoration with process information

README.md

@@ -170,6 +170,8 @@ change the behavior of the debug logging:
 | `DEBUG_COLORS`| Whether or not to use colors in the debug output. |
 | `DEBUG_DEPTH` | Object inspection depth.                    |
 | `DEBUG_SHOW_HIDDEN` | Shows hidden properties on inspected objects. |
+| `DEBUG_PROCESS` | Prefixes logs with a title in square brackets. |
+| `DEBUG_PROCESS_PID` | Prefixes logs with the process id in square brackets. |
 
 
 __Note:__ The environment variables beginning with `DEBUG_` end up being

src/node.js

@@ -161,7 +161,12 @@ function useColors() {
  */
 
 function formatArgs(args) {
-	const {namespace: name, useColors} = this;
+	let {namespace: name, useColors} = this;
+
+	const proc = exports.inspectOpts.process || (exports.inspectOpts.processPid ? process.pid : undefined);
+	if (proc) {
+		name = `[${proc}] ${name}`;
+	}
 
 	if (useColors) {
 		const c = this.color;

test.js

@@ -20,6 +20,36 @@ describe('debug', () => {
 		assert.doesNotThrow(() => debug.enable(true));
 	});
 
+	it('honors process decoration', function() {
+		const options = debug.inspectOpts;
+		if (!options) { // browser
+			this.skip();
+			return;
+		}
+		const optionKeys = ['process', 'processPid', 'colors', 'hideDate'];
+		const oldValues = optionKeys.map(k => debug.inspectOpts[k]);
+
+		try {
+			options.colors = false;
+			options.hideDate = true;
+
+			let messageArgs;
+			const log = debug('bar');
+			log.enabled = true;
+			log.log = (...args) => (messageArgs = args);
+
+			options.processPid = true;
+			log('baz');
+			assert.equal(messageArgs[0], `[${process.pid}] bar baz`, 'should reflect DEBUG_PROCESS_PID');
+
+			options.process = 'foo';
+			log('baz');
+			assert.equal(messageArgs[0], '[foo] bar baz', 'should reflect DEBUG_PROCESS');
+		} finally {
+			optionKeys.forEach((k, i) => options[k] = oldValues[i]);
+		}
+	});
+
 	it('honors global debug namespace enable calls', () => {
 		assert.deepStrictEqual(debug('test:12345').enabled, false);
 		assert.deepStrictEqual(debug('test:67890').enabled, false);