In phalcon3.3.2 composer updatephpunit/phpunit 4.5.0 requires phpunit/php-file-iterator ~1.3.2 -> no matching package found.

{ "require": { "illuminate/validation": "4.2.*", "phalcon/incubator": "^2.0", "phpunit/phpunit": "~4.5" } }

phpunit/phpunit 4.5.1 requires phpunit/php-file-iterator ~1.3.2 -> no matching package found.
- phpunit/phpunit 4.5.0 requires phpunit/php-file-iterator ~1.3.2 -> no matching package found.
- Installation request for phpunit/phpunit ~4.5 -> satisfiable by phpunit/phpunit[4.5.0, 4.5.1, 4.6.0, 4.6.1, 4.6.10, 4.6.2, 4.6.3, 4.6.4, 4.6.5, 4.6.6, 4.6.7, 4.6.8, 4.6.9, 4.7.0, 4.7.1, 4.7.2, 4.7.3, 4.7.4, 4.7.5, 4.7.6, 4.7.7, 4.8.0, 4.8.1, 4.8.10, 4.8.11, 4.8.12, 4.8.13, 4.8.14, 4.8.15, 4.8.16, 4.8.17, 4.8.18, 4.8.19, 4.8.2, 4.8.20, 4.8.21, 4.8.22, 4.8.23, 4.8.24, 4.8.25, 4.8.26, 4.8.27, 4.8.28, 4.8.29, 4.8.3, 4.8.30, 4.8.31, 4.8.32, 4.8.33, 4.8.34, 4.8.35, 4.8.36, 4.8.4, 4.8.5, 4.8.6, 4.8.7, 4.8.8, 4.8.9].

Potential causes:

A typo in the package name
The package is not available in a stable-enough version according to your minimum-stability setting see https://getcomposer.org/doc/04-schema.md#minimum-stability for more details.
It's a private package and you forgot to add a custom repository to find it

phalcon / phalcon-devtools