diff --git a/python/plugins/processing/tests/AlgorithmsTestBase.py b/python/plugins/processing/tests/AlgorithmsTestBase.py
index 2ae126ccbf6..2e19146a7b7 100644
--- a/python/plugins/processing/tests/AlgorithmsTestBase.py
+++ b/python/plugins/processing/tests/AlgorithmsTestBase.py
@@ -287,13 +287,14 @@ class AlgorithmsTest(object):
                     self.assertTrue(result_lyr, results[id])
 
                 compare = expected_result.get('compare', {})
+                pk = expected_result.get('pk', None)
 
                 if len(expected_lyrs) == 1:
-                    self.assertLayersEqual(expected_lyrs[0], result_lyr, compare=compare)
+                    self.assertLayersEqual(expected_lyrs[0], result_lyr, compare=compare, pk=pk)
                 else:
                     res = False
                     for l in expected_lyrs:
-                        if self.checkLayersEqual(l, result_lyr, compare=compare):
+                        if self.checkLayersEqual(l, result_lyr, compare=compare, pk=pk):
                             res = True
                             break
                     self.assertTrue(res, 'Could not find matching layer in expected results')
diff --git a/python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml b/python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml
index 215160793c6..79378a18d39 100644
--- a/python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml
+++ b/python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml
@@ -2501,6 +2501,10 @@ tests:
       OUTPUT:
         name: expected/stats_by_category.gml
         type: vector
+        pk: id2
+        compare:
+          fields:
+            fid: skip
 
 #  - algorithm: qgis:zonalstatistics
 #    name: simple zonal statistics
diff --git a/python/testing/__init__.py b/python/testing/__init__.py
index a495a335681..fc3eafe1fa0 100644
--- a/python/testing/__init__.py
+++ b/python/testing/__init__.py
@@ -54,6 +54,10 @@ class TestCase(_TestCase):
         :keyword compare: A map of comparison options. e.g.
                          { fields: { a: skip, b: { precision: 2 }, geometry: { precision: 5 } }
                          { fields: { __all__: cast( str ) } }
+        :keyword pk: "Primary key" type field - used to match features
+        from the expected table to their corresponding features in the result table. If not specified
+        features are compared by their order in the layer (e.g. first feature compared with first feature,
+        etc)
         """
         self.checkLayersEqual(layer_expected, layer_result, True, **kwargs)
 
@@ -69,6 +73,10 @@ class TestCase(_TestCase):
         :keyword compare: A map of comparison options. e.g.
                          { fields: { a: skip, b: { precision: 2 }, geometry: { precision: 5 } }
                          { fields: { __all__: cast( str ) } }
+        :keyword pk: "Primary key" type field - used to match features
+        from the expected table to their corresponding features in the result table. If not specified
+        features are compared by their order in the layer (e.g. first feature compared with first feature,
+        etc)
         """
 
         try:
@@ -98,8 +106,14 @@ class TestCase(_TestCase):
         except KeyError:
             precision = 14
 
-        expected_features = sorted(layer_expected.getFeatures(request), key=lambda f: f.id())
-        result_features = sorted(layer_result.getFeatures(request), key=lambda f: f.id())
+        def sort_by_pk_or_fid(f):
+            if 'pk' in kwargs and kwargs['pk'] is not None:
+                return f[kwargs['pk']]
+            else:
+                return f.id()
+
+        expected_features = sorted(layer_expected.getFeatures(request), key=sort_by_pk_or_fid)
+        result_features = sorted(layer_result.getFeatures(request), key=sort_by_pk_or_fid)
 
         for feats in zip(expected_features, result_features):
             if feats[0].hasGeometry():