I had to explicitly enable `extension=ext/php_openssl.dll` in php.ini for it to work. The error message that was thrown was:
```
[2013-11-23 12:30:00] EXCEPTION: (FilesystemException) Failed to open /dev/urandom for reading! at [C:\Tools\libphutil\src\filesystem\Filesy
stem.php:400]
#0 Filesystem::readRandomBytes(10) called at [C:\Tools\libphutil\src\filesystem\Filesystem.php:449]
#1 Filesystem::readRandomCharacters(10) called at [C:\Tools\arcanist\src\unit\engine\XUnitTestEngine.php:318]
#2 XUnitTestEngine::buildTestFuture(C:\Users\James\Documents\Projects\Tychaia\Tychaia.Tests/bin/Debug/Tychaia.Tests.dll) called at [C:\Too
ls\arcanist\src\unit\engine\XUnitTestEngine.php:353]
#3 XUnitTestEngine::testAssemblies(Array of size 9 starting with: { 0 => Array of size 2 starting with: { project => C:\Users\James\Docume
nts\Projects\Tychaia\Tychaia.Tests\Tychaia.Tests.Windows.csproj } }) called at [C:\Tools\arcanist\src\unit\engine\XUnitTestEngine.php:171]
#4 XUnitTestEngine::runAllTests(Array of size 9 starting with: { 0 => Array of size 2 starting with: { project => C:\Users\James\Documents
\Projects\Tychaia\Tychaia.Tests\Tychaia.Tests.Windows.csproj } }) called at [C:\Tools\arcanist\src\unit\engine\XUnitTestEngine.php:102]
#5 XUnitTestEngine::run() called at [C:\Tools\arcanist\src\workflow\ArcanistUnitWorkflow.php:173]
#6 ArcanistUnitWorkflow::run() called at [C:\Tools\arcanist\scripts\arcanist.php:321]
```
althrough from the code it looks like the `Filesystem::readRandomBytes() requires at least PHP 5.3 or /dev/urandom` was probably the more intended exception in this case.
For Windows it should probably make it clear what the user needs to do (enable php_openssl.dll in their configuration). In the default Windows binaries that are shipped for PHP, there are no extensions enabled by default, so this is something all Windows users will have to do.