Add 2 full tests for plugin + use env port for test

tests/testcases/case_1/conftest.py

@@ -0,0 +1 @@
+pytest_plugins = "pytest_gui_status.status_plugin"

tests/testcases/case_1/test_1.py

@@ -0,0 +1,6 @@
+def test_pass():
+    assert 1
+
+
+def test_fail():
+    assert 0