write_since(): Include TODO lines from untracked files

Previously, untracked files were not included in the diff, so TODO lines
in those files would not be printed by the program.

Add the untracked `DiffOptions` to include the content of these files
when searching for TODOs.

1 files changed, 10 insertions, 2 deletions

diff --git a/src/lib.rs b/src/lib.rs
index 0fe8f3f..910b488 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -18,7 +18,7 @@
 
 use std::io::Write;
 
-use git2::{Repository, Tree};
+use git2::{DiffOptions, Repository, Tree};
 use thiserror::Error;
 
 
@@ -46,7 +46,15 @@ impl Todos<'_> {
         tree: Tree<'_>,
         write_to: &mut W,
     ) -> Result<(), Error> {
-        let diff = self.repo.diff_tree_to_workdir(Some(&tree), None)?;
+        let mut diff_options = DiffOptions::new();
+        diff_options
+            .show_untracked_content(true)
+            .recurse_untracked_dirs(true);
+
+        let diff = self.repo.diff_tree_to_workdir_with_index(
+            Some(&tree),
+            Some(&mut diff_options),
+        )?;
 
         diff.foreach(
             &mut |_file, _progress| {