Default to a dark gray instead of black for symbol outlines

Avoiding the very high constrast pure black results in cartographically
more pleasing styles, so it's nice to do this by default.

This should result in nicer looking maps being created in QGIS
when users don't do any manual style tweaks.

src/core/symbology/qgsellipsesymbollayer.cpp

@@ -29,7 +29,7 @@
 
 QgsEllipseSymbolLayer::QgsEllipseSymbolLayer()
   : mSymbolName( QStringLiteral( "circle" ) )
-  , mStrokeColor( Qt::black )
+  , mStrokeColor( QColor( 70, 70, 70 ) )
 {
   mColor = Qt::white;
   mPen.setColor( mStrokeColor );

src/core/symbology/qgsfillsymbollayer.cpp

@@ -1712,7 +1712,7 @@ QgsSVGFillSymbolLayer::QgsSVGFillSymbolLayer( const QString &svgFilePath, double
   mStrokeWidth = 0.3;
   mAngle = angle;
   mColor = QColor( 255, 255, 255 );
-  mSvgStrokeColor = QColor( 0, 0, 0 );
+  mSvgStrokeColor = QColor( 70, 70, 70 );
   mSvgStrokeWidth = 0.2;
   setDefaultSvgParams();
   mSvgPattern = nullptr;
@@ -1729,7 +1729,7 @@ QgsSVGFillSymbolLayer::QgsSVGFillSymbolLayer( const QByteArray &svgData, double
   mStrokeWidth = 0.3;
   mAngle = angle;
   mColor = QColor( 255, 255, 255 );
-  mSvgStrokeColor = QColor( 0, 0, 0 );
+  mSvgStrokeColor = QColor( 70, 70, 70 );
   mSvgStrokeWidth = 0.2;
   setSubSymbol( new QgsLineSymbol() );
   setDefaultSvgParams();

src/core/symbology/qgsfillsymbollayer.h

@@ -22,7 +22,7 @@
 
 #define DEFAULT_SIMPLEFILL_COLOR        QColor(0,0,255)
 #define DEFAULT_SIMPLEFILL_STYLE        Qt::SolidPattern
-#define DEFAULT_SIMPLEFILL_BORDERCOLOR  QColor(0,0,0)
+#define DEFAULT_SIMPLEFILL_BORDERCOLOR  QColor( 70, 70, 70 )
 #define DEFAULT_SIMPLEFILL_BORDERSTYLE  Qt::SolidLine
 #define DEFAULT_SIMPLEFILL_BORDERWIDTH  DEFAULT_LINE_WIDTH
 #define DEFAULT_SIMPLEFILL_JOINSTYLE    Qt::BevelJoin

src/core/symbology/qgslinesymbollayer.h

@@ -25,7 +25,7 @@
 
 class QgsExpression;
 
-#define DEFAULT_SIMPLELINE_COLOR     QColor(0,0,0)
+#define DEFAULT_SIMPLELINE_COLOR     QColor(70,70,70)
 #define DEFAULT_SIMPLELINE_WIDTH     DEFAULT_LINE_WIDTH
 #define DEFAULT_SIMPLELINE_PENSTYLE  Qt::SolidLine
 #define DEFAULT_SIMPLELINE_JOINSTYLE Qt::BevelJoin

src/core/symbology/qgsmarkersymbollayer.cpp

@@ -1698,8 +1698,8 @@ QgsSvgMarkerSymbolLayer::QgsSvgMarkerSymbolLayer( const QString &path, double si
   mScaleMethod = scaleMethod;
   mStrokeWidth = 0.2;
   mStrokeWidthUnit = QgsUnitTypes::RenderMillimeters;
-  mColor = QColor( Qt::black );
-  mStrokeColor = QColor( Qt::black );
+  mColor = QColor( 70, 70, 70 );
+  mStrokeColor = QColor( 70, 70, 70 );
   updateDefaultAspectRatio();
 }
 

src/core/symbology/qgsmarkersymbollayer.h

@@ -23,7 +23,7 @@
 
 #define DEFAULT_SIMPLEMARKER_NAME         "circle"
 #define DEFAULT_SIMPLEMARKER_COLOR        QColor(255,0,0)
-#define DEFAULT_SIMPLEMARKER_BORDERCOLOR  QColor(0,0,0)
+#define DEFAULT_SIMPLEMARKER_BORDERCOLOR  QColor( 70, 70, 70 )
 #define DEFAULT_SIMPLEMARKER_JOINSTYLE    Qt::BevelJoin
 #define DEFAULT_SIMPLEMARKER_SIZE         DEFAULT_POINT_SIZE
 #define DEFAULT_SIMPLEMARKER_ANGLE        0
@@ -650,7 +650,7 @@ class CORE_EXPORT QgsSvgMarkerSymbolLayer : public QgsMarkerSymbolLayer
 #define DEFAULT_FONTMARKER_FONT   "Dingbats"
 #define DEFAULT_FONTMARKER_CHR    QChar('A')
 #define DEFAULT_FONTMARKER_SIZE   POINT2MM(12)
-#define DEFAULT_FONTMARKER_COLOR  QColor(Qt::black)
+#define DEFAULT_FONTMARKER_COLOR  QColor( 70, 70, 70 )
 #define DEFAULT_FONTMARKER_BORDERCOLOR  QColor(Qt::white)
 #define DEFAULT_FONTMARKER_JOINSTYLE    Qt::MiterJoin
 #define DEFAULT_FONTMARKER_ANGLE  0

tests/src/core/testqgscentroidfillsymbol.cpp

@@ -30,6 +30,7 @@
 #include <qgssymbol.h>
 #include <qgssinglesymbolrenderer.h>
 #include <qgsfillsymbollayer.h>
+#include "qgsmarkersymbollayer.h"
 
 //qgis test includes
 #include "qgsrenderchecker.h"
@@ -94,6 +95,7 @@ void TestQgsCentroidFillSymbol::initTestCase()
 
   //setup gradient fill
   mCentroidFill = new QgsCentroidFillSymbolLayer();
+  static_cast< QgsSimpleMarkerSymbolLayer * >( mCentroidFill->subSymbol()->symbolLayer( 0 ) )->setStrokeColor( Qt::black );
   mFillSymbol = new QgsFillSymbol();
   mFillSymbol->changeSymbolLayer( 0, mCentroidFill );
   mSymbolRenderer = new QgsSingleSymbolRenderer( mFillSymbol );

tests/src/core/testqgslayertree.cpp

@@ -381,6 +381,7 @@ void TestQgsLayerTree::testLegendSymbolCategorized()
   renderer->setSourceSymbol( QgsSymbol::defaultSymbol( QgsWkbTypes::PointGeometry ) );
   QgsStringMap props;
   props.insert( QStringLiteral( "color" ), QStringLiteral( "#ff0000" ) );
+  props.insert( QStringLiteral( "outline_color" ), QStringLiteral( "#000000" ) );
   renderer->addCategory( QgsRendererCategory( "a", QgsMarkerSymbol::createSimple( props ), QStringLiteral( "a" ) ) );
   props.insert( QStringLiteral( "color" ), QStringLiteral( "#00ff00" ) );
   renderer->addCategory( QgsRendererCategory( "b", QgsMarkerSymbol::createSimple( props ), QStringLiteral( "b" ) ) );
@@ -397,6 +398,7 @@ void TestQgsLayerTree::testLegendSymbolGraduated()
   renderer->setSourceSymbol( QgsSymbol::defaultSymbol( QgsWkbTypes::PointGeometry ) );
   QgsStringMap props;
   props.insert( QStringLiteral( "color" ), QStringLiteral( "#ff0000" ) );
+  props.insert( QStringLiteral( "outline_color" ), QStringLiteral( "#000000" ) );
   renderer->addClass( QgsRendererRange( 1, 2, QgsMarkerSymbol::createSimple( props ), QStringLiteral( "a" ) ) );
   props.insert( QStringLiteral( "color" ), QStringLiteral( "#00ff00" ) );
   renderer->addClass( QgsRendererRange( 2, 3, QgsMarkerSymbol::createSimple( props ), QStringLiteral( "b" ) ) );
@@ -411,6 +413,7 @@ void TestQgsLayerTree::testLegendSymbolRuleBased()
   QgsRuleBasedRenderer::Rule *root = new QgsRuleBasedRenderer::Rule( nullptr );
   QgsStringMap props;
   props.insert( QStringLiteral( "color" ), QStringLiteral( "#ff0000" ) );
+  props.insert( QStringLiteral( "outline_color" ), QStringLiteral( "#000000" ) );
   root->appendChild( new QgsRuleBasedRenderer::Rule( QgsMarkerSymbol::createSimple( props ), 0, 0, QStringLiteral( "\"col1\"=1" ) ) );
   props.insert( QStringLiteral( "color" ), QStringLiteral( "#00ff00" ) );
   root->appendChild( new QgsRuleBasedRenderer::Rule( QgsMarkerSymbol::createSimple( props ), 0, 0, QStringLiteral( "\"col1\"=2" ) ) );
@@ -509,6 +512,7 @@ void TestQgsLayerTree::testRendererLegend( QgsFeatureRenderer *renderer )
   //another test - check directly setting symbol at renderer
   QgsStringMap props;
   props.insert( QStringLiteral( "color" ), QStringLiteral( "#00ffff" ) );
+  props.insert( QStringLiteral( "outline_color" ), QStringLiteral( "#000000" ) );
   renderer->setLegendSymbolItem( symbolList.at( 2 ).ruleKey(), QgsMarkerSymbol::createSimple( props ) );
   m->refreshLayerLegend( n );
   symbolNode = dynamic_cast< QgsSymbolLegendNode * >( m->findLegendNode( vl->id(), symbolList.at( 2 ).ruleKey() ) );

tests/src/core/testqgslayoutatlas.cpp

@@ -130,6 +130,7 @@ void TestQgsLayoutAtlas::init()
   // fix the renderer, fill with green
   QgsStringMap props;
   props.insert( QStringLiteral( "color" ), QStringLiteral( "0,127,0" ) );
+  props.insert( QStringLiteral( "outline_color" ), QStringLiteral( "0,0,0" ) );
   QgsFillSymbol *fillSymbol = QgsFillSymbol::createSimple( props );
   QgsSingleSymbolRenderer *renderer = new QgsSingleSymbolRenderer( fillSymbol );
   mVectorLayer->setRenderer( renderer );
@@ -157,6 +158,7 @@ void TestQgsLayoutAtlas::init()
   // set the fill symbol of the overview map
   QgsStringMap props2;
   props2.insert( QStringLiteral( "color" ), QStringLiteral( "127,0,0,127" ) );
+  props2.insert( QStringLiteral( "outline_color" ), QStringLiteral( "0,0,0" ) );
   QgsFillSymbol *fillSymbol2 = QgsFillSymbol::createSimple( props2 );
   mOverview->overview()->setFrameSymbol( fillSymbol2 );
 

tests/src/core/testqgslayoutitem.cpp

@@ -1877,6 +1877,7 @@ void TestQgsLayoutItem::blendMode()
   QgsFillSymbol *fillSymbol = new QgsFillSymbol();
   fillSymbol->changeSymbolLayer( 0, simpleFill );
   simpleFill->setColor( QColor( 255, 150, 0 ) );
+  simpleFill->setStrokeColor( Qt::black );
   mComposerRect1->setSymbol( fillSymbol );
   delete fillSymbol;
 
@@ -1889,6 +1890,7 @@ void TestQgsLayoutItem::blendMode()
   QgsFillSymbol *fillSymbol2 = new QgsFillSymbol();
   fillSymbol2->changeSymbolLayer( 0, simpleFill2 );
   simpleFill2->setColor( QColor( 0, 100, 150 ) );
+  simpleFill2->setStrokeColor( Qt::black );
   mComposerRect2->setSymbol( fillSymbol2 );
   delete fillSymbol2;
 
@@ -1926,6 +1928,7 @@ void TestQgsLayoutItem::opacity()
   QgsFillSymbol *fillSymbol = new QgsFillSymbol();
   fillSymbol->changeSymbolLayer( 0, simpleFill );
   simpleFill->setColor( QColor( 255, 150, 0 ) );
+  simpleFill->setStrokeColor( Qt::black );
   mComposerRect1->setSymbol( fillSymbol );
   delete fillSymbol;
 
@@ -1938,6 +1941,7 @@ void TestQgsLayoutItem::opacity()
   QgsFillSymbol *fillSymbol2 = new QgsFillSymbol();
   fillSymbol2->changeSymbolLayer( 0, simpleFill2 );
   simpleFill2->setColor( QColor( 0, 100, 150 ) );
+  simpleFill2->setStrokeColor( Qt::black );
   mComposerRect2->setSymbol( fillSymbol2 );
   delete fillSymbol2;
 

tests/src/core/testqgslayoutmapgrid.cpp

@@ -20,6 +20,7 @@
 #include "qgsmultirenderchecker.h"
 #include "qgslayoutitemmap.h"
 #include "qgslayoutitemmapgrid.h"
+#include "qgsmarkersymbollayer.h"
 #include "qgsfontutils.h"
 #include "qgsproject.h"
 #include <QObject>
@@ -233,6 +234,7 @@ void TestQgsLayoutMapGrid::markerGrid()
   map->grid()->setIntervalY( 2000 );
   map->grid()->setGridLineWidth( 0.5 );
   map->grid()->setGridLineColor( QColor( 0, 0, 0 ) );
+  static_cast< QgsSimpleMarkerSymbolLayer * >( map->grid()->markerSymbol()->symbolLayer( 0 ) )->setStrokeColor( Qt::black );
   map->updateBoundingRect();
   l.addLayoutItem( map );
 

tests/src/core/testqgslayoutpage.cpp

@@ -24,6 +24,7 @@
 #include "qgssinglesymbolrenderer.h"
 #include "qgsfillsymbollayer.h"
 #include "qgslinesymbollayer.h"
+#include "qgsmarkersymbollayer.h"
 #include "qgsmultirenderchecker.h"
 #include "qgslayoutpagecollection.h"
 #include <QObject>
@@ -234,6 +235,7 @@ void TestQgsLayoutPage::markerLinePaper()
   l.pageCollection()->addPage( page.release() );
 
   QgsMarkerLineSymbolLayer *markerLine = new QgsMarkerLineSymbolLayer();
+  static_cast< QgsSimpleMarkerSymbolLayer * >( markerLine->subSymbol()->symbolLayer( 0 ) )->setStrokeColor( Qt::black );
   std::unique_ptr< QgsFillSymbol > markerLineSymbol = qgis::make_unique< QgsFillSymbol >();
   markerLineSymbol->changeSymbolLayer( 0, markerLine );
   l.pageCollection()->setPageStyleSymbol( markerLineSymbol.get() );

tests/src/core/testqgslayoutshapes.cpp

@@ -303,6 +303,7 @@ void TestQgsLayoutShapes::shapeRotation()
   QgsFillSymbol *fillSymbol = new QgsFillSymbol();
   fillSymbol->changeSymbolLayer( 0, simpleFill );
   simpleFill->setColor( QColor( 255, 150, 0 ) );
+  simpleFill->setStrokeColor( Qt::black );
   //simpleFill->setStrokeColor( Qt::yellow );
   //simpleFill->setStrokeWidth( 6 );
   shape->setSymbol( fillSymbol );

tests/src/core/testqgspointpatternfillsymbol.cpp

@@ -133,6 +133,7 @@ void TestQgsPointPatternFillSymbol::pointPatternFillSymbol()
 
   QgsStringMap properties;
   properties.insert( QStringLiteral( "color" ), QStringLiteral( "0,0,0,255" ) );
+  properties.insert( QStringLiteral( "outline_color" ), QStringLiteral( "#000000" ) );
   properties.insert( QStringLiteral( "name" ), QStringLiteral( "circle" ) );
   properties.insert( QStringLiteral( "size" ), QStringLiteral( "5.0" ) );
   QgsMarkerSymbol *pointSymbol = QgsMarkerSymbol::createSimple( properties );
@@ -147,6 +148,7 @@ void TestQgsPointPatternFillSymbol::dataDefinedSubSymbol()
 
   QgsStringMap properties;
   properties.insert( QStringLiteral( "color" ), QStringLiteral( "0,0,0,255" ) );
+  properties.insert( QStringLiteral( "outline_color" ), QStringLiteral( "#000000" ) );
   properties.insert( QStringLiteral( "name" ), QStringLiteral( "circle" ) );
   properties.insert( QStringLiteral( "size" ), QStringLiteral( "5.0" ) );
   QgsMarkerSymbol *pointSymbol = QgsMarkerSymbol::createSimple( properties );

tests/src/core/testqgssymbol.cpp

@@ -30,6 +30,7 @@
 #include "qgslinesymbollayer.h"
 #include "qgsfillsymbollayer.h"
 #include "qgssinglesymbolrenderer.h"
+#include "qgsmarkersymbollayer.h"
 
 #include "qgsstyle.h"
 
@@ -177,6 +178,7 @@ void TestQgsSymbol::testCanvasClip()
 
   QgsMarkerLineSymbolLayer *markerLine = new QgsMarkerLineSymbolLayer();
   markerLine->setPlacement( QgsMarkerLineSymbolLayer:: CentralPoint );
+  static_cast< QgsSimpleMarkerSymbolLayer *>( markerLine->subSymbol()->symbolLayer( 0 ) )->setStrokeColor( Qt::black );
   QgsLineSymbol *lineSymbol = new QgsLineSymbol();
   lineSymbol->changeSymbolLayer( 0, markerLine );
   QgsSingleSymbolRenderer *renderer = new QgsSingleSymbolRenderer( lineSymbol );
@@ -196,6 +198,7 @@ void TestQgsSymbol::testCanvasClip()
   ms.setLayers( QList<QgsMapLayer *>() << mpPolysLayer );
 
   QgsCentroidFillSymbolLayer *centroidFill = new QgsCentroidFillSymbolLayer();
+  static_cast< QgsSimpleMarkerSymbolLayer * >( centroidFill->subSymbol()->symbolLayer( 0 ) )->setStrokeColor( Qt::black );
   QgsFillSymbol *fillSymbol = new QgsFillSymbol();
   fillSymbol->changeSymbolLayer( 0, centroidFill );
   renderer = new QgsSingleSymbolRenderer( fillSymbol );

tests/src/python/test_qgsannotation.py

@@ -55,6 +55,8 @@ def tearDown(self):
     def testTextAnnotation(self):
         """ test rendering a text annotation"""
         a = QgsTextAnnotation()
+        a.fillSymbol().symbolLayer(0).setStrokeColor(QColor(0, 0, 0))
+        a.markerSymbol().symbolLayer(0).setStrokeColor(QColor(0, 0, 0))
         a.setFrameSize(QSizeF(300, 200))
         a.setFrameOffsetFromReferencePoint(QPointF(40, 50))
         doc = QTextDocument()
@@ -71,6 +73,8 @@ def testTextAnnotation(self):
     def testSvgAnnotation(self):
         """ test rendering a svg annotation"""
         a = QgsSvgAnnotation()
+        a.fillSymbol().symbolLayer(0).setStrokeColor(QColor(0, 0, 0))
+        a.markerSymbol().symbolLayer(0).setStrokeColor(QColor(0, 0, 0))
         a.setFrameSize(QSizeF(300, 200))
         a.setFrameOffsetFromReferencePoint(QPointF(40, 50))
         svg = TEST_DATA_DIR + "/sample_svg.svg"
@@ -86,6 +90,8 @@ def testSvgAnnotation(self):
     def testHtmlAnnotation(self):
         """ test rendering a html annotation"""
         a = QgsHtmlAnnotation()
+        a.fillSymbol().symbolLayer(0).setStrokeColor(QColor(0, 0, 0))
+        a.markerSymbol().symbolLayer(0).setStrokeColor(QColor(0, 0, 0))
         a.setFrameSize(QSizeF(400, 250))
         a.setFrameOffsetFromReferencePoint(QPointF(70, 90))
         html = TEST_DATA_DIR + "/test_html.html"
@@ -104,6 +110,8 @@ def testHtmlAnnotationWithFeature(self):
                                'test', "memory")
 
         a = QgsHtmlAnnotation()
+        a.fillSymbol().symbolLayer(0).setStrokeColor(QColor(0, 0, 0))
+        a.markerSymbol().symbolLayer(0).setStrokeColor(QColor(0, 0, 0))
         a.setFrameSize(QSizeF(400, 250))
         a.setFrameOffsetFromReferencePoint(QPointF(70, 90))
         a.setMapLayer(layer)
@@ -121,6 +129,7 @@ def testHtmlAnnotationWithFeature(self):
     def testRelativePosition(self):
         """ test rendering an annotation without map point"""
         a = QgsHtmlAnnotation()
+        a.fillSymbol().symbolLayer(0).setStrokeColor(QColor(0, 0, 0))
         a.setFrameSize(QSizeF(400, 250))
         a.setHasFixedMapPosition(False)
         html = TEST_DATA_DIR + "/test_html.html"
@@ -131,6 +140,7 @@ def testRelativePosition(self):
     def testMargins(self):
         """ test rendering an annotation with margins"""
         a = QgsHtmlAnnotation()
+        a.fillSymbol().symbolLayer(0).setStrokeColor(QColor(0, 0, 0))
         a.setFrameSize(QSizeF(400, 250))
         a.setHasFixedMapPosition(False)
         a.setContentsMargin(QgsMargins(15, 10, 30, 20))
@@ -144,7 +154,7 @@ def testFillSymbol(self):
         a = QgsTextAnnotation()
         a.setFrameSize(QSizeF(400, 250))
         a.setHasFixedMapPosition(False)
-        a.setFillSymbol(QgsFillSymbol.createSimple({'color': 'blue', 'width_border': '5'}))
+        a.setFillSymbol(QgsFillSymbol.createSimple({'color': 'blue', 'width_border': '5', 'outline_color': 'black'}))
         im = self.renderAnnotation(a, QPointF(20, 30))
         self.assertTrue(self.imageCheck('annotation_fillstyle', 'annotation_fillstyle', im))
 

tests/src/python/test_qgsfillsymbollayers.py

@@ -58,6 +58,7 @@ def testSimpleLineWithOffset(self):
         """ test that rendering a polygon with simple line symbol with offset results in closed line"""
         layer = QgsSimpleLineSymbolLayer()
         layer.setOffset(-1)
+        layer.setColor(QColor(0, 0, 0))
 
         symbol = QgsFillSymbol()
         symbol.changeSymbolLayer(0, layer)

tests/src/python/test_qgsgeometrygeneratorsymbollayer.py

@@ -28,7 +28,7 @@
 import os
 
 from qgis.PyQt.QtCore import QSize
-
+from qgis.PyQt.QtGui import QColor
 from qgis.core import (
     QgsVectorLayer,
     QgsSingleSymbolRenderer,
@@ -68,9 +68,9 @@ def setUp(self):
         QgsProject.instance().addMapLayer(self.points_layer)
 
         # Create style
-        sym1 = QgsFillSymbol.createSimple({'color': '#fdbf6f'})
+        sym1 = QgsFillSymbol.createSimple({'color': '#fdbf6f', 'outline_color': 'black'})
         sym2 = QgsLineSymbol.createSimple({'color': '#fdbf6f'})
-        sym3 = QgsMarkerSymbol.createSimple({'color': '#fdbf6f'})
+        sym3 = QgsMarkerSymbol.createSimple({'color': '#fdbf6f', 'outline_color': 'black'})
 
         self.polys_layer.setRenderer(QgsSingleSymbolRenderer(sym1))
         self.lines_layer.setRenderer(QgsSingleSymbolRenderer(sym2))
@@ -88,6 +88,7 @@ def test_marker(self):
         sym = self.polys_layer.renderer().symbol()
         sym_layer = QgsGeometryGeneratorSymbolLayer.create({'geometryModifier': 'centroid($geometry)'})
         sym_layer.setSymbolType(QgsSymbol.Marker)
+        sym_layer.subSymbol().symbolLayer(0).setStrokeColor(QColor(0, 0, 0))
         sym.changeSymbolLayer(0, sym_layer)
 
         rendered_layers = [self.polys_layer]
@@ -101,12 +102,14 @@ def test_marker(self):
     def test_mixed(self):
         sym = self.polys_layer.renderer().symbol()
 
-        buffer_layer = QgsGeometryGeneratorSymbolLayer.create({'geometryModifier': 'buffer($geometry, "value"/15)'})
+        buffer_layer = QgsGeometryGeneratorSymbolLayer.create({'geometryModifier': 'buffer($geometry, "value"/15)', 'outline_color': 'black'})
         buffer_layer.setSymbolType(QgsSymbol.Fill)
+        buffer_layer.subSymbol().symbolLayer(0).setStrokeColor(QColor(0, 0, 0))
         self.assertIsNotNone(buffer_layer.subSymbol())
         sym.appendSymbolLayer(buffer_layer)
-        marker_layer = QgsGeometryGeneratorSymbolLayer.create({'geometryModifier': 'centroid($geometry)'})
+        marker_layer = QgsGeometryGeneratorSymbolLayer.create({'geometryModifier': 'centroid($geometry)', 'outline_color': 'black'})
         marker_layer.setSymbolType(QgsSymbol.Marker)
+        marker_layer.subSymbol().symbolLayer(0).setStrokeColor(QColor(0, 0, 0))
         sym.appendSymbolLayer(marker_layer)
 
         rendered_layers = [self.polys_layer]
@@ -120,7 +123,7 @@ def test_mixed(self):
     def test_buffer_lines(self):
         sym = self.lines_layer.renderer().symbol()
 
-        buffer_layer = QgsGeometryGeneratorSymbolLayer.create({'geometryModifier': 'buffer($geometry, "value"/15)'})
+        buffer_layer = QgsGeometryGeneratorSymbolLayer.create({'geometryModifier': 'buffer($geometry, "value"/15)', 'outline_color': 'black'})
         buffer_layer.setSymbolType(QgsSymbol.Fill)
         self.assertIsNotNone(buffer_layer.subSymbol())
         sym.appendSymbolLayer(buffer_layer)
@@ -136,7 +139,7 @@ def test_buffer_lines(self):
     def test_buffer_points(self):
         sym = self.points_layer.renderer().symbol()
 
-        buffer_layer = QgsGeometryGeneratorSymbolLayer.create({'geometryModifier': 'buffer($geometry, "staff"/15)'})
+        buffer_layer = QgsGeometryGeneratorSymbolLayer.create({'geometryModifier': 'buffer($geometry, "staff"/15)', 'outline_color': 'black'})
         buffer_layer.setSymbolType(QgsSymbol.Fill)
         self.assertIsNotNone(buffer_layer.subSymbol())
         sym.appendSymbolLayer(buffer_layer)