Fix test

python/plugins/processing/gui/NumberInputPanel.py

@@ -224,7 +224,7 @@ def getLayerFromValue(self, value):
             value, ok = value.source.valueAsString(context.expressionContext())
         if isinstance(value, str):
             value = QgsProcessingUtils.mapLayerFromString(value, context)
-        if value is None:
+        if value is None or not isinstance(value, QgsMapLayer):
             return None
 
         # need to return layer with ownership - otherwise layer may be deleted when context

python/plugins/processing/tests/GuiTest.py

@@ -29,7 +29,8 @@
 from qgis.core import (QgsApplication,
                        QgsCoordinateReferenceSystem,
                        QgsProcessingParameterMatrix,
-                       QgsVectorLayer)
+                       QgsVectorLayer,
+                       QgsProject)
 from qgis.analysis import QgsNativeAlgorithms
 
 from processing.gui.AlgorithmDialog import AlgorithmDialog
@@ -152,11 +153,21 @@ def testDistance(self):
         widget.setUnitParameterValue(vl)
         self.assertEqual(widget.label.text(), 'meters')
         self.assertFalse(widget.warning_label.isVisible())
-        vl = QgsVectorLayer("Polygon?crs=epsg:4326&field=pk:int", "vl", "memory")
-        widget.setUnitParameterValue(vl)
+        vl2 = QgsVectorLayer("Polygon?crs=epsg:4326&field=pk:int", "vl", "memory")
+        widget.setUnitParameterValue(vl2)
         self.assertEqual(widget.label.text(), 'degrees')
         self.assertTrue(widget.warning_label.isVisible())
 
+        # unresolvable values
+        widget.setUnitParameterValue(vl.id())
+        self.assertEqual(widget.label.text(), '<unknown>')
+        self.assertFalse(widget.warning_label.isVisible())
+        # resolvable text value
+        QgsProject.instance().addMapLayer(vl)
+        widget.setUnitParameterValue(vl.id())
+        self.assertEqual(widget.label.text(), 'meters')
+        self.assertFalse(widget.warning_label.isVisible())
+
         widget.deleteLater()
 
     def testMatrix(self):