More logging to debug failed listing due to invalid format

Summary: Many tests are failing due to the error "Failed to list tests". Logs include the error "The data couldn’t be read because it isn’t in the correct format." Current logs indicate that reading the data may be truncated- length of the data seems to be either 0 or smaller than on successful runs. This diff logs the contents of the temporary file that should contain test data if it is not read successfully.

Differential Revision: D65140844

fbshipit-source-id: 23a56b4ec869aa39b46f8cc10ddc39d0f9755c95

XCTestBootstrap/Strategies/FBListTestStrategy.m

@@ -171,7 +171,7 @@ - (instancetype)initWithTarget:(id<FBiOSTarget, FBProcessSpawnCommands, FBXCTest
       NSError *error = nil;
       NSArray<NSDictionary<NSString *, NSString *> *> *tests = [NSJSONSerialization JSONObjectWithData:shimBuffer.data options:0 error:&error];
       if (!tests) {
-        NSLog(@"Shimulator buffer data (should contain test information): %@", shimBuffer.data);
+        NSLog(@"Shimulator buffer data (should contain test information): %@", [[NSString alloc] initWithData:shimBuffer.data encoding:NSUTF8StringEncoding]);
         return [FBFuture futureWithError:error];
       }
       NSMutableArray<NSString *> *testNames = [NSMutableArray array];