test(editor): view-mode cycling and visibility

Author: woodheng

tests/test_view_modes.py

@@ -0,0 +1,18 @@
+"""Editor view-mode state machine cycling and visibility."""
+import view_modes
+
+
+def test_cycle_order():
+    assert view_modes.next_mode(view_modes.EDIT) == view_modes.SPLIT
+    assert view_modes.next_mode(view_modes.SPLIT) == view_modes.PREVIEW
+    assert view_modes.next_mode(view_modes.PREVIEW) == view_modes.EDIT
+
+
+def test_cycle_unknown_resets_to_edit():
+    assert view_modes.next_mode("bogus") == view_modes.EDIT
+
+
+def test_visibility():
+    assert view_modes.visibility(view_modes.EDIT) == (True, False)
+    assert view_modes.visibility(view_modes.SPLIT) == (True, True)
+    assert view_modes.visibility(view_modes.PREVIEW) == (False, True)