[New] Add comment formatting

Author: Eric Millin

lib/test.js

@@ -1,6 +1,7 @@
 var deepEqual = require('deep-equal');
 var defined = require('defined');
 var path = require('path');
+var format = require('util').format;
 var inherits = require('inherits');
 var EventEmitter = require('events').EventEmitter;
 var has = require('has');
@@ -121,7 +122,11 @@ Test.prototype.test = function (name, opts, cb) {
 
 Test.prototype.comment = function (msg) {
     var that = this;
-    forEach(trim(msg).split('\n'), function (aMsg) {
+    // Previous behavior involved `toString` calls on objects, i.e. emitting `[object Object]`.
+    // `util.format`, however, will print stringified objects. To maintain backward compatibility
+    // check the args length and only call `util.format` if the invoker desires string expansion.
+    var message = arguments.length > 1 ? format.apply(null, arguments) : msg;
+    forEach(trim(message).split('\n'), function (aMsg) {
         that.emit('result', trim(aMsg).replace(/^#\s*/, ''));
     });
 };

readme.markdown

@@ -277,9 +277,9 @@ after `t` will not be run until all subtests finish.
 
 You may pass the same options that [`test()`](#testname-opts-cb) accepts.
 
-## t.comment(message)
+## t.comment(message[, ...])
 
-Print a message without breaking the tap output. (Useful when using e.g. `tap-colorize` where output is buffered & `console.log` will print in incorrect order vis-a-vis tap output.)
+Print a message without breaking the tap output. Accepts optional args for `util.format`-style formatting. Useful when using e.g. `tap-colorize` where output is buffered & `console.log` will print in incorrect order vis-a-vis tap output.
 
 ## var htest = test.createHarness()
 

test/comment.js

@@ -173,3 +173,57 @@ tap.test('multiline string', function (assert) {
         t.end();
     });
 });
+
+tap.test('formatted string', function (assert) {
+    assert.plan(1);
+
+    var verify = function (output) {
+         assert.equal(output.toString('utf8'), [
+                'TAP version 13',
+                '# formatted string',
+                '# tip tap tape',
+                '',
+                '1..0',
+                '# tests 0',
+                '# pass  0',
+                '',
+                '# ok',
+                ''
+        ].join('\n'));
+    };
+
+    var test = tape.createHarness();
+    test.createStream().pipe(concat(verify));
+    test('formatted string', function (t) {
+        t.comment("tip %s t%s", "tap", "ape");
+        t.end();
+    });
+});
+
+tap.test('formatted multiline string', function (assert) {
+    assert.plan(1);
+
+    var verify = function (output) {
+         assert.equal(output.toString('utf8'), [
+                'TAP version 13',
+                '# formatted multiline string',
+                '# tip',
+                '# tap',
+                '# tape',
+                '',
+                '1..0',
+                '# tests 0',
+                '# pass  0',
+                '',
+                '# ok',
+                ''
+        ].join('\n'));
+    };
+
+    var test = tape.createHarness();
+    test.createStream().pipe(concat(verify));
+    test('formatted multiline string', function (t) {
+        t.comment("tip\n%s\nt%s", "tap", "ape");
+        t.end();
+    });
+});