added support for setting bus mode through dict

bus modes added to all 3 example configs.

config unit tests added

tests/test_configs.py

@@ -0,0 +1,34 @@
+import time
+
+import pytest
+
+from tests import data, tests
+
+
+class TestUserConfigs:
+    __test__ = True
+
+    """example config tests"""
+
+    @classmethod
+    def setup_class(cls):
+        tests.apply_config("example")
+
+    def test_it_tests_config_string(self):
+        assert "PhysStrip" in tests.strip[data.phys_in].label
+        assert "VirtStrip" in tests.strip[data.virt_in].label
+
+    def test_it_tests_config_bool(self):
+        assert tests.strip[0].A1 == True
+
+    @pytest.mark.skipif(
+        "not config.getoption('--run-slow')",
+        reason="Only run when --run-slow is given",
+    )
+    def test_it_tests_config_busmode(self):
+        assert tests.bus[data.phys_out].mode.get() == "composite"
+
+    def test_it_tests_config_bass_med_high(self):
+        assert tests.strip[data.virt_in].bass == -3.2
+        assert tests.strip[data.virt_in].mid == 1.5
+        assert tests.strip[data.virt_in].high == 2.1