Add some tests

tests/src/python/test_qgsexpression.py

@@ -14,6 +14,7 @@ __revision__ = '$Format:%H$'
 
 import qgis  # NOQA
 
+from qgis.PyQt.QtCore import QVariant
 from qgis.testing import unittest
 from qgis.utils import qgsfunction
 from qgis.core import QgsExpression, QgsFeatureRequest
@@ -196,6 +197,39 @@ class TestQgsExpressionCustomFunctions(unittest.TestCase):
         e.setExpression('1')
         self.assertTrue(e.isValid())
 
+    def testCreateFieldEqualityExpression(self):
+        e = QgsExpression()
+
+        # test when value is null
+        field = "myfield"
+        value = QVariant()
+        res = '"myfield" IS NULL'
+        self.assertEqual(e.createFieldEqualityExpression(field, value), res)
+
+        # test when value is null and field name has a quote
+        field = "my'field"
+        value = QVariant()
+        res = '"my\'field" IS NULL'
+        self.assertEqual(e.createFieldEqualityExpression(field, value), res)
+
+        # test when field name has a quote and value is an int
+        field = "my'field"
+        value = 5
+        res = '"my\'field" = 5'
+        self.assertEqual(e.createFieldEqualityExpression(field, value), res)
+
+        # test when field name has a quote and value is a string
+        field = "my'field"
+        value = '5'
+        res = '"my\'field" = \'5\''
+        self.assertEqual(e.createFieldEqualityExpression(field, value), res)
+
+        # test when field name has a quote and value is a boolean
+        field = "my'field"
+        value = True
+        res = '"my\'field" = TRUE'
+        self.assertEqual(e.createFieldEqualityExpression(field, value), res)
+
 
 if __name__ == "__main__":
     unittest.main()