feat(expect): updates test suite to use expectation api

tests/Expect/toBeTrue.php

@@ -0,0 +1,15 @@
+<?php
+
+use PHPUnit\Framework\ExpectationFailedException;
+
+test('strict comparisons', function () {
+    expect(true)->toBeTrue();
+});
+
+test('failures', function () {
+    expect('')->toBeTrue();
+})->throws(ExpectationFailedException::class);
+
+test('not failures', function () {
+    expect(false)->not->toBe(false);
+})->throws(ExpectationFailedException::class);