Create gradle.properties in ProcessingPluginTest

Add creation of sketch/gradle.properties in ProcessingPluginTest, writing processing.group derived from System.getProperty("project.group").replace(".java", ""). This ensures the test project has the expected processing.group property within the tests

Author: Stefterv

java/gradle/src/test/kotlin/ProcessingPluginTest.kt

@@ -24,6 +24,11 @@ class ProcessingPluginTest{
             }
         """.trimIndent())
         directory.newFile("sketch/settings.gradle.kts")
+        directory.newFile("sketch/gradle.properties").writeText(
+            """
+            processing.group=${System.getProperty("project.group").replace(".java", "")}
+            """.trimIndent()
+        )
         configure(sketchFolder)
 
         val buildResult = GradleRunner.create()
@@ -218,6 +223,7 @@ class ProcessingPluginTest{
             """.trimIndent())
             sketchFolder.resolve("gradle.properties").writeText(""")
                 processing.workingDir = ${sketchFolder.parentFile.absolutePath}
+                processing.group=${System.getProperty("project.group").replace(".java", "")}
             """.trimIndent())
         }
         val sketchClass = classLoader.loadClass("sketch")
@@ -250,9 +256,12 @@ class ProcessingPluginTest{
                     println("Hello World");
                 }
             """.trimIndent())
-            sketchFolder.resolve("gradle.properties").writeText(""")
+            sketchFolder.resolve("gradle.properties").writeText(
+                """
                 processing.sketchbook = ${libraryResult.libraryFolder.parentFile.parentFile.absolutePath}
-            """.trimIndent())
+                processing.group=${System.getProperty("project.group").replace(".java", "")}
+                """.trimIndent()
+            )
         }
 
         val sketchClass = classLoader.loadClass("sketch")