Unrecognized Selector SenTestCase for Category

I was searching for an answer this problem myself and found (I believe) a simpler solution, which doesn't require remembering to add a reference in the Compile Sources list whenever a new category class is added to the project.

In the test target's build settings, add -ObjC to the Linking / Other Linker Flags value.

Further explanation for why this error actually happens can be found at Apple Reference.

Edit: Be sure to see this answer about unit test not finding files

+1 For uploading the project. The problem is your test target does not include NSString+Inflections.m in the Build Phases.

In XCode 4

1. Click "Poppy" in the top of the Navigator
2. Select "PoppyTests" under Targets
3. Go to Build Phases
4. Expand Compile Sources
5. Click the + sign and then add NSString+Inflections.m

You should then get something similar the following output

TestSuite '/blahblah/PoppyTests.octest(Tests)' finished at 2011-03-28 21:31:34 +0000. Executed 1 test, with 1 failure (0 unexpected) in 0.000 (0.002) seconds

I can also confirm that adding the required files to the Test project's Build Phases > Compile Sources collection solves this problem. Thanks a bunch!

When I tried the -all_load approach, however, I started to receive a bunch of errors, like that _CGSizeZero is undefined for architecture i386. It turns out that some code - like this one, where I use CGSizeZero in one of my classes - can make the second approach break.

Once I replaced CGSizeZero with CGSizeMake(0, 0), however, the second approach worked great as well.