Add GC tests for line dash, line attributes and handling device scaling

No basic tests exist for the setLineDash and setLineAttributes methods
of the GC class. In addition, the functionalities for setting line width
and line dash (including setting the LineAttributes), are not validated
with respect to an applied device zoom.
This change adds according tests to the Test_org_eclipse_swt_graphics_GC
class.

tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_graphics_GC.java

@@ -15,6 +15,7 @@
 package org.eclipse.swt.tests.junit;
 
 import static org.eclipse.swt.tests.junit.SwtTestUtil.assertSWTProblem;
+import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotEquals;
@@ -29,6 +30,7 @@
 import org.eclipse.swt.graphics.GC;
 import org.eclipse.swt.graphics.Image;
 import org.eclipse.swt.graphics.ImageData;
+import org.eclipse.swt.graphics.LineAttributes;
 import org.eclipse.swt.graphics.PaletteData;
 import org.eclipse.swt.graphics.Point;
 import org.eclipse.swt.graphics.RGB;
@@ -584,6 +586,32 @@ public void test_setForegroundLorg_eclipse_swt_graphics_Color() {
 	}
 }
 
+@Test
+public void test_setLineAttributes$I() {
+	int width = 1;
+	int cap = 3;
+	int join = 2;
+	int style = 6;
+	float[] dashes = new float[] { 1.2f, 3.3f };
+	float dashOffset = 3.3f;
+	float miterLimit = 2.6f;
+	gc.setLineAttributes(new LineAttributes(width, cap, join, style, dashes, dashOffset, miterLimit));
+	assertEquals("unexpected line width", width, gc.getLineWidth());
+	assertEquals("unexpected line cap", cap, gc.getLineCap());
+	assertEquals("unexpected line join", join, gc.getLineJoin());
+	assertEquals("unexpected line style", style, gc.getLineStyle());
+	assertEquals("actual line attributes differ from the ones that have been set",
+			new LineAttributes(width, cap, join, style, dashes, dashOffset, miterLimit), gc.getLineAttributes());
+
+	gc.setLineAttributes(new LineAttributes(1));
+	assertEquals(new LineAttributes(1), gc.getLineAttributes());
+}
+
+@Test
+public void test_setLineAttributes$I_withDeviceScaling() {
+	executeWithNonDefaultDeviceZoom(() -> test_setLineAttributes$I());
+}
+
 @Test
 public void test_setLineStyleI() {
 	gc.setLineStyle(SWT.LINE_SOLID);
@@ -606,6 +634,25 @@ public void test_setLineWidthI() {
 	assertEquals(0, gc.getLineWidth());
 }
 
+@Test
+public void test_setLineWidthI_withDeviceScaling() {
+	executeWithNonDefaultDeviceZoom(() -> test_setLineWidthI());
+}
+
+@Test
+public void test_setLineDash$I() {
+	int[] dashes = new int[] { 5, 1, 3 };
+	gc.setLineDash(dashes);
+	assertArrayEquals(dashes, gc.getLineDash());
+	gc.setLineDash(null);
+	assertEquals(null, gc.getLineDash());
+}
+
+@Test
+public void test_setLineDash$I_withDeviceScaling() {
+	executeWithNonDefaultDeviceZoom(() -> test_setLineDash$I());
+}
+
 @Test
 public void test_setXORModeZ() {
 	gc.setXORMode(true);
@@ -714,4 +761,14 @@ RGB getRealRGB(Color color) {
 	pixel = imageData.getPixel(0, 0);
 	return palette.getRGB(pixel);
 }
+
+private void executeWithNonDefaultDeviceZoom(Runnable executable) {
+	int previousDeviceZoom = DPIUtil.getDeviceZoom();
+	DPIUtil.setDeviceZoom(150);
+	try {
+		executable.run();
+	} finally {
+		DPIUtil.setDeviceZoom(previousDeviceZoom);
+	}
+}
 }