Support headless testing with monocle

todolist/fxui/pom.xml

@@ -13,6 +13,7 @@
 
     <properties>
         <skipUiTests>false</skipUiTests>
+        <headlessTests>false</headlessTests>
     </properties>
 
     <dependencies>
@@ -167,6 +168,22 @@
                 </plugins>
             </build>
         </profile>
+
+        <profile>
+            <id>headless</id>
+            <properties>
+                <headlessTests>true</headlessTests>
+            </properties>
+            <dependencies>
+                <!-- https://mvnrepository.com/artifact/org.testfx/openjfx-monocle -->
+                <dependency>
+                    <groupId>org.testfx</groupId>
+                    <artifactId>openjfx-monocle</artifactId>
+                    <version>jdk-12.0.1+2</version>
+                    <scope>test</scope>
+                </dependency>
+            </dependencies>
+        </profile>
     </profiles>
 
     <build>
@@ -179,8 +196,13 @@
                 <artifactId>maven-surefire-plugin</artifactId>
                 <configuration>
                     <skipTests>${skipUiTests}</skipTests>
+                    <systemPropertyVariables>
+                        <headless>${headlessTests}</headless>
+                    </systemPropertyVariables>
                     <argLine>
-                    @{jaCoCoArgLine} --add-opens todolist.ui/todolist.ui=ALL-UNNAMED --add-exports javafx.graphics/com.sun.javafx.application=ALL-UNNAMED
+                    @{jaCoCoArgLine}
+                    --add-opens todolist.ui/todolist.ui=ALL-UNNAMED --add-exports javafx.graphics/com.sun.javafx.application=ALL-UNNAMED
+                    --add-opens javafx.graphics/com.sun.glass.ui=ALL-UNNAMED --add-exports javafx.graphics/com.sun.glass.ui=ALL-UNNAMED
                     </argLine>
                 </configuration>
             </plugin>

todolist/fxui/src/test/java/todolist/ui/TodoAppTest.java

@@ -10,12 +10,29 @@ import static org.junit.jupiter.api.Assertions.fail;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.io.Reader;
+
+import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.testfx.framework.junit5.ApplicationTest;
 
 public class TodoAppTest extends ApplicationTest {
 
+  static void supportHeadlessTest() {
+    if (Boolean.getBoolean("headless")) {
+        System.setProperty("testfx.robot", "glass");
+        System.setProperty("testfx.headless", "true");
+        System.setProperty("prism.order", "sw");
+        System.setProperty("prism.text", "t2k");
+        System.setProperty("java.awt.headless", "true");
+    }
+  }
+
+  @BeforeAll
+  public static void setupHeadless() {
+    supportHeadlessTest();
+  }
+
   private TodoModelController controller;
 
   @Override

todolist/fxui/src/test/java/todolist/ui/TodoListControllerTest.java

@@ -16,6 +16,8 @@ import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assertions.fail;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
@@ -31,6 +33,11 @@ import todolist.json.TodoPersistence;
 
 public class TodoListControllerTest extends ApplicationTest {
 
+  @BeforeAll
+  public static void setupHeadless() {
+    TodoAppTest.supportHeadlessTest();
+  }
+
   private TodoListController controller;
 
   @Override