Fix QgsClipboard::retrieveFields and adapt unit test (because features without geometries are now allowed in QgsClipboard)

Author: mhugent

src/app/qgsclipboard.cpp

@@ -255,11 +255,22 @@ QgsFields QgsClipboard::retrieveFields() const
   QgsFields f = QgsOgrUtils::stringToFields( string, QTextCodec::codecForName( "System" ) );
   if ( f.size() < 1 )
   {
+    if ( string.isEmpty() )
+    {
+      return f;
+    }
+
     //wkt?
     QStringList lines = string.split( "\n" );
     if ( lines.size() > 0 )
     {
       QStringList fieldNames = lines.at( 0 ).split( "\t" );
+      //wkt / text always has wkt_geom as first attribute (however values can be NULL)
+      if ( fieldNames.at( 0 ) != "wkt_geom" )
+      {
+        return f;
+      }
+
       for ( int i = 0; i < fieldNames.size(); ++i )
       {
         QString fieldName = fieldNames.at( i );

tests/src/app/testqgisappclipboard.cpp

@@ -241,10 +241,10 @@ void TestQgisAppClipboard::pasteWkt()
   QCOMPARE( point->x(), 125.0 );
   QCOMPARE( point->y(), 10.0 );
 
-  // only fields => no geom so no feature list is returned
+  //clipboard now supports features without geometry
   mQgisApp->clipboard()->setText( QStringLiteral( "MNL		11	282	km			\nMNL		11	347.80000000000001	km				" ) );
   features = mQgisApp->clipboard()->copyOf();
-  QCOMPARE( features.length(), 0 );
+  QCOMPARE( features.length(), 2 );
 }
 
 void TestQgisAppClipboard::pasteGeoJson()