doProcess example

$container->setParameter('env(NULLED)', null);
        $container->setParameter('env(FLOATISH)', '3.2');
        $container->registerExtension($ext = new EnvExtension());
        $container->prependExtensionConfig('env_extension', $expected = [
            'scalar_node' => '%env(NULLED)%',
            'scalar_node_not_empty' => '%env(FLOATISH)%',
            'int_node' => '%env(int:FOO)%',
            'float_node' => '%env(float:BAR)%',
            'string_node' => '%env(UNDEFINED)%',
        ]);

        $this->doProcess($container);

        $this->assertSame($expected, $container->resolveEnvPlaceholders($ext->getConfig()));
    }

    public function testDefaultEnvIsValidatedInConfig()
    {
        $this->expectException(InvalidConfigurationException::class);
        $this->expectExceptionMessage('Invalid configuration for path "env_extension.string_node": "fail" is not a valid string');
        $container = new ContainerBuilder();
        $container->setParameter('env(STRING)', 'fail');
        $container->registerExtension($ext = new EnvExtension());