Runs UI tests on CI Servers Headless with Monocle

Trying to run the tests with xvfb was causing tests to fail.
This should resolve this problem.

Author: JLLeitschuh

.travis.yml

@@ -26,7 +26,7 @@ install:
   - '[ "${TRAVIS_PULL_REQUEST}" = "false" ] && ./gradlew :ui:assemble --stacktrace || ./gradlew --stacktrace '
 
 script:
-  - ./gradlew check --stacktrace -PprintTestResults
+  - ./gradlew check --stacktrace -Pheadless=true
 
 after_success:
   - codecov

appveyor.yml

@@ -2,11 +2,11 @@ install:
   - choco install -y InnoSetup
 
 build_script:
-  - gradlew.bat :ui:assemble --stacktrace -PprintTestResults
+  - gradlew.bat :ui:assemble --stacktrace
 
 # to run your custom scripts instead of automatic tests
 test_script:
-  - gradlew.bat check --stacktrace -PprintTestResults
+  - gradlew.bat check --stacktrace -Pheadless=true
 
 platform:
   - x64

build.gradle

@@ -290,6 +290,7 @@ project(":ui") {
         testCompile files(project(':core').sourceSets.test.output.resourcesDir)
         testCompile group: 'org.testfx', name: 'testfx-core', version: '4.0.+'
         testCompile group: 'org.testfx', name: 'testfx-junit', version: '4.0.+'
+        testRuntime group: 'org.testfx', name: 'openjfx-monocle', version: '1.8.0_20'
     }
 
     evaluationDependsOn(':core')
@@ -299,6 +300,17 @@ project(":ui") {
         scopes.PROVIDED.plus += [configurations.ideProvider]
     }
 
+    /*
+     * Allows you to run the UI tests in headless mode by calling gradle with the -Pheadless=true argument
+     */
+    if (project.hasProperty('headless') && project.headless) {
+        println "Running UI Tests Headless"
+        test {
+            jvmArgs = ['-Djava.awt.headless=true', '-Dtestfx.robot=glass', '-Dtestfx.headless=true', '-Dprism.order=sw', '-Dprism.text=t2k']
+        }
+    }
+
+
     javafx {
         profiles {
             linux {