Add integration test for headless mode config

Author: ctrueden

tests/it/headless.py

@@ -0,0 +1,19 @@
+"""
+Test scyjava headless mode.
+"""
+
+import scyjava
+
+scyjava.config.enable_headless_mode()
+
+assert not scyjava.jvm_started()
+scyjava.start_jvm()
+
+assert scyjava.is_jvm_headless()
+
+Frame = scyjava.jimport("java.awt.Frame")
+try:
+    f = Frame()
+    assert False, "HeadlessException should have occurred"
+except Exception as e:
+    assert "java.awt.HeadlessException" == str(e)