diff --git a/docs/GerarCertificadoAutoAssinadoParaTestes.md b/docs/GerarCertificadoAutoAssinadoParaTestes.md
new file mode 100644
index 00000000..43d8c449
--- /dev/null
+++ b/docs/GerarCertificadoAutoAssinadoParaTestes.md
@@ -0,0 +1,90 @@
+# Gerar Certificado auto assinado
+
+## Para um CNPJ
+1 - Gerar chave privada:
+```
+openssl genpkey -algorithm RSA -out private.key -pkeyopt rsa_keygen_bits:2048
+```
+
+2 - Crie o arquivo de configuração openssl.cnf:
+
+```
+[ req ]
+distinguished_name = req_distinguished_name
+x509_extensions = v3_ca
+req_extensions = v3_req
+
+[ req_distinguished_name ]
+C = BR
+ST = São Paulo
+L = São Paulo
+O = Sua Empresa
+OU = Unidade de TI
+CN = 05.730.928/0001-45
+emailAddress = email@suaempresa.com.br
+
+[ v3_ca ]
+subjectAltName = @alt_names
+basicConstraints = CA:TRUE
+keyUsage = keyCertSign, cRLSign
+
+[ v3_req ]
+basicConstraints = CA:FALSE
+keyUsage = nonRepudiation, digitalSignature, keyEncipherment
+subjectAltName = @alt_names
+2.16.76.1.3.3 = ASN1:UTF8String:05730928000145
+
+[ alt_names ]
+email = email@suaempresa.com.br
+```
+
+3 - Gere o certificado autoassinado:
+
+```bash
+openssl req -new -x509 -days 3650 -key private.key -out certificate.crt -config openssl.cnf -extensions v3_req
+```
+
+4 - Converta para o formato PFX:
+
+```bash
+openssl pkcs12 -export -out certificate.pfx -inkey private.key -in certificate.crt -certfile certificate.crt -passout pass:minhasenha
+```
+
+
+## Para um CPF
+
+Mesmos passos anteriores, exeto o arquivo openssl.cnf será esse abaixo.
+Note que o oid 2.16.76.1.3.1 é composto por uma data de nascimento seguido do CPF.
+2.16.76.1.3.1 = ASN1:UTF8String:ddddddddccccccccccc
+Onde d é data de nascimento e c é o cpf somente números.
+
+```
+[ req ]
+distinguished_name = req_distinguished_name
+x509_extensions = v3_ca
+req_extensions = v3_req
+
+[ req_distinguished_name ]
+C = BR
+ST = São Paulo
+L = São Paulo
+O = SpedNfe
+OU = Unidade de TI
+CN = 904.839.260-86
+emailAddress = email@suaempresa.com.br
+
+[ v3_ca ]
+subjectAltName = @alt_names
+basicConstraints = CA:TRUE
+keyUsage = keyCertSign, cRLSign
+
+[ v3_req ]
+basicConstraints = CA:FALSE
+keyUsage = nonRepudiation, digitalSignature, keyEncipherment
+subjectAltName = @alt_names
+2.16.76.1.3.1 = ASN1:UTF8String:1210198506157250000116
+
+[ alt_names ]
+email = email@suaempresa.com.br
+
+```
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index bc4d4807..552bb022 100755
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
-         bootstrap="vendor/autoload.php"
+         bootstrap="tests/bootstrap.php"
          backupGlobals="false"
          backupStaticAttributes="false"
          colors="true"
diff --git a/tests/CertificateTest.php b/tests/CertificateTest.php
new file mode 100644
index 00000000..af897969
--- /dev/null
+++ b/tests/CertificateTest.php
@@ -0,0 +1,25 @@
+<?php
+
+namespace NFePHP\NFe\Tests;
+
+use NFePHP\Common\Certificate;
+use PHPUnit\Framework\TestCase;
+
+class CertificateTest extends TestCase
+{
+    public function test_certificado_pj(): void
+    {
+        $conteudo = file_get_contents(TESTS_FIXTURES  . '/certs/cert_cnpj_06157250000116_senha_minhasenha.pfx');
+        $certificado = Certificate::readPfx($conteudo, 'minhasenha');
+        $this->assertSame('06157250000116', $certificado->getCnpj());
+        $this->assertSame('05/06/2034', $certificado->getValidTo()->format('d/m/Y'));
+    }
+
+    public function test_certificado_pf(): void
+    {
+        $conteudo = file_get_contents(TESTS_FIXTURES  . '/certs/cert_cpf_90483926086_minhasenha.pfx');
+        $certificado = Certificate::readPfx($conteudo, 'minhasenha');
+        $this->assertSame('90483926086', $certificado->getCpf());
+        $this->assertSame('03/06/2034', $certificado->getValidTo()->format('d/m/Y'));
+    }
+}
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
new file mode 100644
index 00000000..eb04cdc6
--- /dev/null
+++ b/tests/bootstrap.php
@@ -0,0 +1,4 @@
+<?php
+
+include dirname(__DIR__) . '/vendor/autoload.php';
+include __DIR__ . '/constantes.php';
diff --git a/tests/constantes.php b/tests/constantes.php
new file mode 100644
index 00000000..7caeba63
--- /dev/null
+++ b/tests/constantes.php
@@ -0,0 +1,3 @@
+<?php
+
+define('TESTS_FIXTURES', __DIR__ . '/fixtures');
diff --git a/tests/fixtures/certs/cert_cnpj_06157250000116_senha_minhasenha.pfx b/tests/fixtures/certs/cert_cnpj_06157250000116_senha_minhasenha.pfx
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diff --git a/tests/fixtures/certs/cert_cpf_90483926086_minhasenha.pfx b/tests/fixtures/certs/cert_cpf_90483926086_minhasenha.pfx
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