feat: move Expectations API out of external plugin

tests/Features/Expect/toEqualCanonicalizing.php

@@ -0,0 +1,16 @@
+<?php
+
+use PHPUnit\Framework\ExpectationFailedException;
+
+test('pass', function () {
+    expect([1, 2, 3])->toEqualCanonicalizing([3, 1, 2]);
+    expect(['g', 'a', 'z'])->not->toEqualCanonicalizing(['a', 'z']);
+});
+
+test('failures', function () {
+    expect([3, 2, 1])->toEqualCanonicalizing([1, 2]);
+})->throws(ExpectationFailedException::class);
+
+test('not failures', function () {
+    expect(['a', 'b', 'c'])->not->toEqualCanonicalizing(['b', 'a', 'c']);
+})->throws(ExpectationFailedException::class);