feat: add toBeStudlyCase

src/Mixins/Expectation.php

@@ -1045,4 +1045,16 @@ final class Expectation
 
         return $this;
     }
+
+    /**
+     * Asserts that the value is StudlyCase.
+     *
+     * @return self<TValue>
+     */
+    public function toBeStudlyCase(string $message = ''): self
+    {
+        Assert::assertTrue((bool) preg_match('/^\p{Lu}+\p{Ll}[\p{Ll}\p{Lu}]+$/u', (string) $this->value), $message);
+
+        return $this;
+    }
 }

tests/Features/Expect/toBeStudlyCase.php

@@ -0,0 +1,23 @@
+<?php
+
+use PHPUnit\Framework\ExpectationFailedException;
+
+test('pass', function () {
+    expect('Abc')->toBeStudlyCase();
+    expect('AbcDef')->toBeStudlyCase();
+    expect('abc-def')->not->toBeStudlyCase();
+    expect('abc-def')->not->toBeStudlyCase();
+    expect('abc')->not->toBeStudlyCase();
+});
+
+test('failures', function () {
+    expect('abc')->toBeStudlyCase();
+})->throws(ExpectationFailedException::class);
+
+test('failures with custom message', function () {
+    expect('abc')->toBeStudlyCase('oh no!');
+})->throws(ExpectationFailedException::class, 'oh no!');
+
+test('not failures', function () {
+    expect('AbcDef')->not->toBeStudlyCase();
+})->throws(ExpectationFailedException::class);