add test with leading plan

[Krinkle]

Upon reviewing this for potential adoption, I was confused by the following code:

function check() {
	// ..
	if (seen.plan === null || seen.asserts.length < seen.plan) { return; }
	finish();
}

// …

p.on('assert', function (result) {
	seen.asserts.push(result);
	check();
});

p.on('plan', function (plan) {
	seen.plan = plan.end - plan.start;
});

If my understanding of the TAP spec is correct, a plan like 1..4 represents 4 tests from test 1 to test 4. The above appears to have an off-by-one error where it stores 4 - 1 = 3, and the check ends as soon as length == 3, i.e. after test 3 instead of after test 4.

I noticed there was no test case with a leading plan yet, and writing one, it appears to fail. But, perhas I'm misunderstanding how this is supposed to work. In case this is a bug, here's what I found so far.

$ node test/leading.js 
TAP version 13
# (anonymous)
## [test] write: TAP version 13
## [test] write: 1..3
## [src] plan event { start: 1, end: 3 } 2
## [test] write: ok 1 first
## [test] write: ok 2 what
## [src] assert event 1
## [test] write: ok 3 third base
## [src] assert event 2
## [src] check() calls finish()
## [src] finish() calls p.end()
## [src] complete event
ok 1 should be strictly equal
not ok 2 results object
  ---
    operator: deepLooseEqual
    expected: |-
      { ok: true, count: 3, pass: 3, fail: 0, bailout: false, todo: 0, skip: 0, plan: { start: 1, end: 3, skipAll: false, skipReason: '', comment: '' }, failures: [], asserts: [ { ok: true, id: 1, name: 'first' }, { ok: true, id: 2, name: 'second' }, { ok: true, id: 2, name: 'third base' } ] }
    actual: |-
      { ok: false, count: 2, pass: 2, fail: 1, bailout: false, todo: 0, skip: 0, plan: FinalPlan { start: 1, end: 3, skipAll: false, skipReason: '', comment: '' }, failures: [ { tapError: 'incorrect number of tests' } ], asserts: [ Result { ok: true, id: 1, name: 'first' }, Result { ok: true, id: 2, name: 'what' } ] }
    at: snip
  ...
## [test] write: 
## [test] write: # weeeee
## [test] write: undefined

I added a return; to the test code where it writes the last undefined, but that made no difference (treated as ignored extra). Adding +1 to seen.plan seems like the obvious fix, but produces a different error instead. I assumed that the reason assert event 3 was never emitted by the parser is that after event 2 the stream is closed by calling p.end(). However with the fix applied, the event still isn't emitted. It seems tap-parser doesn't want to emit it yet until the next test or a test plan appears. I added an empty line and a comment at the end but it still won't emit it.

$ node test/leading.js 
TAP version 13
# (anonymous)
## [test] write: TAP version 13
## [test] write: 1..3
## [src] plan event { start: 1, end: 3 } 3
## [test] write: ok 1 first
## [test] write: ok 2 what
## [src] assert event 1
## [test] write: ok 3 third base
## [src] assert event 2
## [test] write: 
## [test] write: # weeeee
not ok 1 plan != count
  ---
    operator: fail
    expected: 2
    actual:   0
    at: process.<anonymous> (/Users/krinkle/Temp/tap-finished/node_modules/tape/index.js:169:8)
    stack: |-
      Error: plan != count
          at Test.assert [as _assert] (/Users/krinkle/Temp/tap-finished/node_modules/tape/lib/test.js:492:48)
          at Test.fail (/Users/krinkle/Temp/tap-finished/node_modules/tape/lib/test.js:600:7)
          at Test._exit (/Users/krinkle/Temp/tap-finished/node_modules/tape/lib/test.js:443:8)
          at process.<anonymous> (/Users/krinkle/Temp/tap-finished/node_modules/tape/index.js:169:8)
          at process.emit (node:events:515:28)
  ...

1..1

Debug diff

diff --git a/index.js b/index.js
index 4fea2698bf..67d5c8af7b 100644
--- a/index.js
+++ b/index.js
@@ -23,29 +23,39 @@ module.exports = function (opts, cb) {
 			cb(assign({}, finalResult, { asserts: seen.asserts }));
 		});
 		if (opts.wait && !ended) {
+			console.info('## [src] finish() calls setTimeout()');
 			setTimeout(function () { p.end(); }, opts.wait);
-		} else { p.end(); }
+		} else {
+			console.info('## [src] finish() calls p.end()');
+			p.end();
+		}
 	}
 
 	function check() {
 		if (finished) { return; }
 		if (seen.plan === null || seen.asserts.length < seen.plan) { return; }
+		console.info('## [src] check() calls finish()');
 		finish();
 	}
 
-	p.on('end', function () { ended = true; });
+	p.on('end', function () {
+		console.info('## [src] end event');
+		ended = true;
+	});
 
 	p.on('assert', function (result) {
-		seen.asserts.push(result);
+		console.info('## [src] assert event', seen.asserts.push(result));
 		check();
 	});
 
 	p.on('plan', function (plan) {
-		seen.plan = plan.end - plan.start;
+		seen.plan = plan.end - (plan.start - 1);
+		console.info('## [src] plan event', plan, seen.plan);
 		check();
 	});
 
 	p.on('complete', function () {
+		console.info('## [src] complete event');
 		if (finished) { return; }
 		finish();
 	});
diff --git a/test/all_ok.js b/test/all_ok.js
index 93641d8025..7da1e86407 100644
--- a/test/all_ok.js
+++ b/test/all_ok.js
@@ -46,6 +46,7 @@ test(function (t) {
 		if (lines.length === 0) {
 			clearInterval(iv);
 			done = true;
+			return;
 		}
 
 		var line = lines.shift();
diff --git a/test/excess.js b/test/excess.js
index fcf1f2406a..4e15ba2ce1 100644
--- a/test/excess.js
+++ b/test/excess.js
@@ -49,6 +49,7 @@ test(function (t) {
 		if (lines.length === 0) {
 			clearInterval(iv);
 			done = true;
+			return;
 		}
 
 		var line = lines.shift();
diff --git a/test/leading.js b/test/leading.js
index 2eb092bbd6..f0700196de 100644
--- a/test/leading.js
+++ b/test/leading.js
@@ -51,7 +51,7 @@ test(function (t) {
 		}
 
 		var line = lines.shift();
-		console.log('# write: ' + line);
+		console.log('## [test] write: ' + line);
 		stream.write(line + '\n');
 	}, 25);
 });