Add test units for special columns in QgsExpression

Author: Hugo Mercier

tests/src/core/testqgsexpression.cpp

@@ -541,6 +541,33 @@ class TestQgsExpression: public QObject
       QVariant vPerimeter = exp3.evaluate( &fPolygon );
       QCOMPARE( vPerimeter.toDouble(), 20. );
     }
+
+  void eval_special_columns()
+  {
+    QTest::addColumn<QString>( "string" );
+    QTest::addColumn<QVariant>( "result" );
+
+    QgsExpression::setSpecialColumn( "$var1", QVariant((int)42) );
+
+    QgsExpression exp( "$var1 + 1" );
+    QVariant v1 = exp.evaluate();
+    QCOMPARE( v1.toInt(), 43 );
+    
+    QgsExpression::setSpecialColumn( "$var1", QVariant((int)100) );
+    QVariant v2 = exp.evaluate();
+    QCOMPARE( v2.toInt(), 101 );
+
+    QgsExpression exp2( "_specialcol_('$var1')+1" );
+    QVariant v3 = exp2.evaluate();
+    QCOMPARE( v3.toInt(), 101 );
+
+    QgsExpression exp3( "_specialcol_('undefined')");
+    QVariant v4 = exp3.evaluate();
+    QCOMPARE( v4, QVariant() );
+
+    QgsExpression::unsetSpecialColumn( "$var1" );
+  }
+
 };
 
 QTEST_MAIN( TestQgsExpression )