fix handling of plan() not matching assertions

lib/test.js

@@ -1,5 +1,6 @@
 'use strict';
 var util = require('util');
+var assert = require('assert');
 var EventEmitter = require('events').EventEmitter;
 var fnName = require('fn-name');
 var claim = require('claim');
@@ -32,9 +33,7 @@ function Test(title, fn) {
 
 	// TODO: find a better way to count assertions
 	this.onAssert(function () {
-		this.assertCount++;
-
-		if (this.assertCount === this.planCount) {
+		if (++this.assertCount === this.planCount) {
 			setImmediate(this.exit.bind(this));
 		}
 	}.bind(this));
@@ -114,7 +113,12 @@ Test.prototype.end = function () {
 
 Test.prototype.exit = function () {
 	if (this.planCount !== null && this.planCount !== this.assertCount) {
-		throw new Error('Assertion count does not match planned');
+		this.assertError = new assert.AssertionError({
+			actual: this.assertCount,
+			expected: this.planCount,
+			message: 'Assertion count does not match planned',
+			operator: 'plan'
+		});
 	}
 
 	if (!this.ended) {

test/test.js

@@ -55,8 +55,7 @@ test('plan assertions', function (t) {
 	});
 });
 
-// TODO: fix how we throw assertion error when plan count doesn't match
-test.skip('run more assertions than planned', function (t) {
+test('run more assertions than planned', function (t) {
 	ava(function (a) {
 		a.plan(2);
 		a.true(true);
@@ -229,17 +228,20 @@ test('async assertion with `.end()`', function (t) {
 	});
 });
 
-test.skip('more assertions than planned should emit an assertion error', function (t) {
+test('more assertions than planned should emit an assertion error', function (t) {
 	ava(function (a) {
 		a.plan(1);
 		a.pass();
 		a.pass();
 	}).run(function (err) {
 		t.true(err, err);
+		t.is(err.name, 'AssertionError');
 		t.end();
 	});
 });
 
+// NOTE(sindresorhus): I don't think this is possible as we won't know when the last assertion will happen, it could be minutes.
+// Might be able to check `process._getActiveHandles().length === 1 && process._getActiveRequests().length === 0` or something.
 test.skip('more assertions than planned should emit an assertion error - async', function (t) {
 	ava(function (a) {
 		a.plan(1);
@@ -250,6 +252,7 @@ test.skip('more assertions than planned should emit an assertion error - async',
 		}, 100);
 	}).run(function (err) {
 		t.true(err, err);
+		t.is(err.name, 'AssertionError');
 		t.end();
 	});
 });