diff --git a/src/Framework/Assert.php b/src/Framework/Assert.php
index eeaf9aa6..f9e63346 100644
--- a/src/Framework/Assert.php
+++ b/src/Framework/Assert.php
@@ -151,6 +151,38 @@ public static function notContains($needle, $actual, string $description = null)
 	}
 
 
+	/**
+	 * Asserts that a haystack has an expected key.
+	 * @param  string|int  $key
+	 */
+	public static function hasKey($key, array $actual, string $description = null): void
+	{
+		self::$counter++;
+		if (!is_int($key) && !is_string($key)) {
+			self::fail(self::describe('Key %1 should be string or integer'), $key);
+
+		} elseif (!array_key_exists($key, $actual)) {
+			self::fail(self::describe('%1 should contain key %2', $description), $actual, $key);
+		}
+	}
+
+
+	/**
+	 * Asserts that a haystack doesn't have an expected key.
+	 * @param  string|int  $key
+	 */
+	public static function hasNotKey($key, array $actual, string $description = null): void
+	{
+		self::$counter++;
+		if (!is_int($key) && !is_string($key)) {
+			self::fail(self::describe('Key %1 should be string or integer'), $key);
+
+		} elseif (array_key_exists($key, $actual)) {
+			self::fail(self::describe('%1 should not contain key %2', $description), $actual, $key);
+		}
+	}
+
+
 	/**
 	 * Asserts that a value is true.
 	 * @param  mixed  $actual
diff --git a/tests/Framework/Assert.hasKey.phpt b/tests/Framework/Assert.hasKey.phpt
new file mode 100644
index 00000000..360b63cd
--- /dev/null
+++ b/tests/Framework/Assert.hasKey.phpt
@@ -0,0 +1,58 @@
+<?php
+
+declare(strict_types=1);
+
+use Tester\Assert;
+
+require __DIR__ . '/../bootstrap.php';
+
+
+$array = [
+	1 => 1,
+	'one' => 'one',
+];
+
+$string= 'Lorem ipsum';
+
+Assert::hasKey(1, $array);
+Assert::hasKey('1', $array);
+Assert::hasKey('one', $array);
+
+Assert::hasNotKey(2, $array);
+Assert::hasNotKey('two', $array);
+
+foreach ([[], true, false, null, new stdClass, 1.0] as $key) {
+	Assert::exception(function () use ($key, $array) {
+		Assert::hasKey($key, $array);
+	}, Tester\AssertException::class, 'Key %a% should be string or integer');
+
+	Assert::exception(function () use ($key, $array) {
+		Assert::hasNotKey($key, $array);
+	}, Tester\AssertException::class, 'Key %a% should be string or integer');
+}
+
+Assert::exception(function () use ($array) {
+	Assert::hasKey(2, $array);
+}, Tester\AssertException::class, '%a% should contain key %a%');
+
+Assert::exception(function () use ($array) {
+	Assert::hasKey('two', $array);
+}, Tester\AssertException::class, '%a% should contain key %a%');
+
+
+Assert::exception(function () use ($array) {
+	Assert::hasNotKey(1, $array);
+}, Tester\AssertException::class, '%a% should not contain key %a%');
+
+Assert::exception(function () use ($array) {
+	Assert::hasNotKey('one', $array);
+}, Tester\AssertException::class, '%a% should not contain key %a%');
+
+
+Assert::exception(function () use ($array) {
+	Assert::hasKey('two', $array, 'Custom description');
+}, Tester\AssertException::class, "Custom description: [1 => 1, 'one' => 'one'] should contain key 'two'");
+
+Assert::exception(function () use ($array) {
+	Assert::hasNotKey('one', $array, 'Custom description');
+}, Tester\AssertException::class, "Custom description: [1 => 1, 'one' => 'one'] should not contain key 'one'");