test(config): add CertConfig unit tests

Signed-off-by: Vitor Mattos <vitor@php.rio>

Author: vitormattos

tests/Unit/Config/CertConfigTest.php

@@ -0,0 +1,69 @@
+<?php
+
+// SPDX-FileCopyrightText: 2026 LibreCode coop and contributors
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+declare(strict_types=1);
+
+namespace LibreCodeCoop\NfsePHP\Tests\Unit\Config;
+
+use LibreCodeCoop\NfsePHP\Config\CertConfig;
+use LibreCodeCoop\NfsePHP\Tests\TestCase;
+
+/**
+ * @covers \LibreCodeCoop\NfsePHP\Config\CertConfig
+ */
+class CertConfigTest extends TestCase
+{
+    public function testStoresAllProperties(): void
+    {
+        $config = new CertConfig(
+            cnpj:      '29842527000145',
+            pfxPath:   '/etc/nfse/certs/company.pfx',
+            vaultPath: 'secret/nfse/29842527000145',
+        );
+
+        self::assertSame('29842527000145', $config->cnpj);
+        self::assertSame('/etc/nfse/certs/company.pfx', $config->pfxPath);
+        self::assertSame('secret/nfse/29842527000145', $config->vaultPath);
+    }
+
+    public function testCnpjIsReadonly(): void
+    {
+        $config = new CertConfig(
+            cnpj:      '29842527000145',
+            pfxPath:   '/etc/nfse/certs/company.pfx',
+            vaultPath: 'secret/nfse/29842527000145',
+        );
+
+        $this->expectException(\Error::class);
+        /** @phpstan-ignore-next-line */
+        $config->cnpj = 'other';
+    }
+
+    public function testPfxPathIsReadonly(): void
+    {
+        $config = new CertConfig(
+            cnpj:      '29842527000145',
+            pfxPath:   '/etc/nfse/certs/company.pfx',
+            vaultPath: 'secret/nfse/29842527000145',
+        );
+
+        $this->expectException(\Error::class);
+        /** @phpstan-ignore-next-line */
+        $config->pfxPath = 'other';
+    }
+
+    public function testVaultPathIsReadonly(): void
+    {
+        $config = new CertConfig(
+            cnpj:      '29842527000145',
+            pfxPath:   '/etc/nfse/certs/company.pfx',
+            vaultPath: 'secret/nfse/29842527000145',
+        );
+
+        $this->expectException(\Error::class);
+        /** @phpstan-ignore-next-line */
+        $config->vaultPath = 'other';
+    }
+}