Add a conflict test for worktree changes.

crates/but-core/tests/core/worktree.rs

@@ -424,6 +424,23 @@ fn file_to_symlink_in_worktree() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn conflict() -> Result<()> {
+    let repo = repo("conflicting")?;
+    let actual = changes(&repo)?;
+    insta::assert_debug_snapshot!(actual, @r#"
+    [
+        TreeChange {
+            path: "conflicting",
+            status: Conflict(
+                BothModified,
+            ),
+        },
+    ]
+    "#);
+    Ok(())
+}
+
 #[test]
 #[cfg(unix)]
 fn file_to_symlink_in_index() -> Result<()> {

crates/but-core/tests/fixtures/worktree-changes.sh

@@ -129,3 +129,17 @@ cp -Rv case-folding-worktree-changes case-folding-worktree-and-index-changes
 100644 $empty_oid	FILE
 EOF
 )
+
+git init conflicting
+(cd conflicting
+  touch unrelated && git add . && git commit -m "init"
+
+  empty=$(git hash-object -w --stdin </dev/null)
+  a=$(echo "a" | git hash-object -w --stdin)
+  b=$(echo "b" | git hash-object -w --stdin)
+  git update-index --index-info <<EOF
+100644 $empty 1	conflicting
+100644 $a 2	conflicting
+100644 $b 3	conflicting
+EOF
+)