[machineid] Polish up the tests

- create dirs as needed (this will normally be done by
  unsquash, but for tests with paths it needs to be done
  by hand)
- log what file is being checked
- filePath() doesn't like the absolute paths we have
  (they're absolute in the chroot, and existing code
  just sticks rootMountPoint in front)

src/modules/machineid/MachineIdJob.cpp

@@ -77,6 +77,12 @@ MachineIdJob::exec()
     //Create new files
     for ( const auto& entropy_file : m_entropy_files )
     {
+        if ( !CalamaresUtils::System::instance()->createTargetParentDirs( entropy_file ) )
+        {
+            return Calamares::JobResult::error(
+                QObject::tr( "Directory not found" ),
+                QObject::tr( "Could not create new random file <pre>%1</pre>." ).arg( entropy_file ) );
+        }
         auto r = MachineId::createEntropy( m_entropy_copy ? MachineId::EntropyGeneration::CopyFromHost
                                                           : MachineId::EntropyGeneration::New,
                                            root,

src/modules/machineid/Tests.cpp

@@ -235,7 +235,8 @@ MachineIdTests::testJob()
         QVERIFY( r );
         for ( const auto& fileName : j.entropyFileNames() )
         {
-            QVERIFY( QFile::exists( tempRoot.filePath( fileName ) ) );
+            cDebug() << "Verifying existence of" << fileName;
+            QVERIFY( QFile::exists( tempRoot.filePath( fileName.mid( 1 ) ) ) );
         }
     }