This allows us to leave existing test cases entirely unmodified while
switching the project over to XCTest. Unfortunately, this also means
that we lose test support on legacy platforms (i.e. iOS <= 5.x) that do
not support XCTest.
Given that Apple actively discourages legacy support, it doesn't seem
worth blocking compatibility with newer Xcode releases while we try to
find a mechanism to support both OCUnit *and* XCTest.
This commit does not update the iOS targets, and the test runnability
is broken pending those changes.
Issue: PLCR-548
7abc6e83b7