Adds toHaveLength() Expectation & Tests

Adds toHaveLength() Expectation and its tests. toHaveLength checks if the given value has the informed length. Works with strings, array, object and collections.

tests/Features/Expect/toHaveLength.php

@@ -0,0 +1,27 @@
+<?php
+
+use PHPUnit\Framework\ExpectationFailedException;
+
+it('passes', function ($value) {
+    expect($value)->toHaveLength(9);
+})->with([
+    'Fortaleza', 'Sollefteå', 'Ιεράπετρα', 'PT-BR 🇵🇹🇧🇷😎',
+    (object) [1, 2, 3, 4, 5, 6, 7, 8, 9],
+    collect([1, 2, 3, 4, 5, 6, 7, 8, 9]),
+]);
+
+it('passes with array', function () {
+    expect([1, 2, 3])->toHaveLength(3);
+});
+
+it('passes with *not*', function () {
+    expect('')->not->toHaveLength(1);
+});
+
+it('properly fails with *not*', function () {
+    expect('pest')->not->toHaveLength(4);
+})->throws(ExpectationFailedException::class);
+
+it('fails', function ($value) {
+    expect($value)->toHaveLength(1);
+})->with([1, 1.5, true, null])->throws(BadMethodCallException::class);