This is an issue that only presented itself after upgrading from 2017.2 to 2017.3
I depend on a small library that I get from Gradle that I pass to the project at the `setUp()` method of my `LightCodeInsightFixtureTestCase`. This library is acquired using Gradle and passed to the `test` task of Gradle using system properties.
Here's how it's done in the `build.gradle` file, here and here.
And here's how the library is added in the test, here and here.
I have stepped through the code and verified the jar found using the test system property is correct and it does exist. This method also worked reliably up until this point before upgrading to 2017.3.
Nevertheless, any test which uses classes from this library (example) will fail: