Add tests for odd headline levels.

src/context/global_settings.rs

@@ -29,6 +29,8 @@ pub struct GlobalSettings<'g, 's> {
     pub odd_levels_only: HeadlineLevelFilter,
 }
 
+pub const DEFAULT_TAB_WIDTH: IndentationLevel = 8;
+
 impl<'g, 's> GlobalSettings<'g, 's> {
     fn new() -> GlobalSettings<'g, 's> {
         GlobalSettings {
@@ -39,8 +41,8 @@ impl<'g, 's> GlobalSettings<'g, 's> {
             in_progress_todo_keywords: BTreeSet::new(),
             complete_todo_keywords: BTreeSet::new(),
             list_allow_alphabetical: false,
-            tab_width: 8,
-            odd_levels_only: HeadlineLevelFilter::OddEven,
+            tab_width: DEFAULT_TAB_WIDTH,
+            odd_levels_only: HeadlineLevelFilter::default(),
         }
     }
 }
@@ -51,8 +53,14 @@ impl<'g, 's> Default for GlobalSettings<'g, 's> {
     }
 }
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, PartialEq)]
 pub enum HeadlineLevelFilter {
     Odd,
     OddEven,
 }
+
+impl Default for HeadlineLevelFilter {
+    fn default() -> Self {
+        HeadlineLevelFilter::OddEven
+    }
+}

src/context/mod.rs

@@ -26,5 +26,6 @@ pub use file_access_interface::FileAccessInterface;
 pub use file_access_interface::LocalFileAccessInterface;
 pub use global_settings::GlobalSettings;
 pub use global_settings::HeadlineLevelFilter;
+pub use global_settings::DEFAULT_TAB_WIDTH;
 pub(crate) use list::List;
 pub(crate) use parser_with_context::parser_with_context;