diff --git a/pttodoest/src/main.rs b/pttodoest/src/main.rs
index cb8af6c..f046551 100755
--- a/pttodoest/src/main.rs
+++ b/pttodoest/src/main.rs
@@ -104,18 +104,19 @@ mod test_flags {
 
     #[test]
     fn test_flags_files_unhidden_only() {
-        let d = tempdir::TempDir::new("").unwrap();
-        std::fs::File::create(d.path().join("plain")).unwrap();
-        std::fs::File::create(d.path().join(".hidden")).unwrap();
+        tests::with_dir(|d| {
+            std::fs::File::create(d.path().join("plain")).unwrap();
+            std::fs::File::create(d.path().join(".hidden")).unwrap();
 
-        let flags = Flags {
-            path: d.path().to_str().unwrap().to_string(),
-            add: None,
-            edit: false,
-            dry_run: true,
-        };
-        let files = flags.files().expect("failed to files from dir");
-        assert_eq!(1, files.files.len());
+            let flags = Flags {
+                path: d.path().to_str().unwrap().to_string(),
+                add: None,
+                edit: false,
+                dry_run: true,
+            };
+            let files = flags.files().expect("failed to files from dir");
+            assert_eq!(1, files.files.len());
+        });
     }
 }
 
@@ -233,12 +234,28 @@ mod test_file {
     use super::*;
 
     #[test]
-    fn test_file() {
-        let d = tempdir::TempDir::new("").unwrap();
-        let mut f = std::fs::File::create(d.path().join("plain")).unwrap();
-        writeln!(f, "hello world").unwrap();
+    fn test_file_empty() {
+        tests::with_dir(|d| {
+            tests::write_file(&d, "plain", "[]");
 
-        assert!(false, "not impl");
+            let f = File::new(&d.path().join("plain").to_str().unwrap().to_string());
+
+            assert_eq!(0, f.events().unwrap().0.len());
+            assert_eq!(0, f.stage().unwrap().len());
+            tests::file_contains(&d, "plain", "[]");
+
+            f.stage_persisted().unwrap();
+            assert_eq!(0, f.events().unwrap().0.len());
+            assert_eq!(0, f.stage().unwrap().len());
+            tests::file_contains(&d, "plain", "[]");
+
+            f.persist_stage().unwrap();
+            assert_eq!(0, f.events().unwrap().0.len());
+            assert_eq!(0, f.stage().unwrap().len());
+            tests::file_contains(&d, "plain", "[]");
+
+            assert!(false, "not impl");
+        });
     }
 }
 
@@ -360,70 +377,94 @@ mod test_events {
 
     #[test]
     fn test_events_oplog_to_snapshot_one() {
-        let d = tempdir::TempDir::new("").unwrap();
-        test_file(&d, "plain", "- persisted\n- stage only");
-        test_file(
-            &d,
-            ".plain.some_host",
-            r#"
-                {"ts":1, "patch":{"op":"replace", "path":"", "value":["persisted"]}}
-            "#,
-        );
+        tests::with_dir(|d| {
+            tests::write_file(&d, "plain", "- persisted\n- stage only");
+            tests::write_file(
+                &d,
+                ".plain.some_host",
+                r#"
+                    {"ts":1, "patch":{"op":"replace", "path":"", "value":["persisted"]}}
+                "#,
+            );
 
-        let events = Events::new(&d.path().join("plain").to_str().unwrap().to_string()).unwrap();
-        assert_eq!(1, events.0.len(), "events: {:?}", events);
+            let events =
+                Events::new(&d.path().join("plain").to_str().unwrap().to_string()).unwrap();
+            assert_eq!(1, events.0.len(), "events: {:?}", events);
 
-        let snapshot = events.snapshot().unwrap();
-        assert_eq!(1, snapshot.len());
-        assert_eq!(
-            serde_yaml::Value::String("persisted".to_string()),
-            snapshot[0].0
-        );
+            let snapshot = events.snapshot().unwrap();
+            assert_eq!(1, snapshot.len());
+            assert_eq!(
+                serde_yaml::Value::String("persisted".to_string()),
+                snapshot[0].0
+            );
+        });
     }
 
     #[test]
     fn test_events_oplog_to_snapshot_complex() {
-        let d = tempdir::TempDir::new("").unwrap();
-        test_file(&d, "plain", "- ignored");
-        test_file(
-            &d,
-            ".plain.some_host",
-            r#"
-                {"ts":1, "patch":{"op":"replace", "path":"", "value":["persisted"]}}
-                {"ts":3, "patch":{"op":"add", "path":"/-", "value":"persisted 3"}}
-                {"ts":2, "patch":{"op":"add", "path":"/-", "value":"persisted 2"}}
-                {"ts":4, "patch":{"op":"add", "path":"/-", "value":"persisted 4"}}
-                {"ts":5, "patch":{"op":"add", "path":"/-", "value":"persisted 5"}}
-                {"ts":6, "patch":{"op":"replace", "path":"/4", "value":"persisted 5'"}}
-                {"ts":7, "patch":{"op":"remove", "path":"/3"}}
-            "#,
-        );
+        tests::with_dir(|d| {
+            tests::write_file(&d, "plain", "- ignored");
+            tests::write_file(
+                &d,
+                ".plain.host_a",
+                r#"
+                    {"ts":1, "patch":{"op":"replace", "path":"", "value":["persisted"]}}
+                    {"ts":3, "patch":{"op":"add", "path":"/-", "value":"persisted 3"}}
+                    {"ts":2, "patch":{"op":"add", "path":"/-", "value":"persisted 2"}}
+                    {"ts":6, "patch":{"op":"replace", "path":"/4", "value":"persisted 5'"}}
+                    {"ts":7, "patch":{"op":"remove", "path":"/3"}}
+                "#,
+            );
+            tests::write_file(
+                &d,
+                ".plain.host_b",
+                r#"
+                    {"ts":4, "patch":{"op":"add", "path":"/-", "value":"persisted 4"}}
+                    {"ts":5, "patch":{"op":"add", "path":"/-", "value":"persisted 5"}}
+                "#,
+            );
 
-        let events = Events::new(&d.path().join("plain").to_str().unwrap().to_string()).unwrap();
+            let events =
+                Events::new(&d.path().join("plain").to_str().unwrap().to_string()).unwrap();
 
-        let snapshot = events.snapshot().unwrap();
-        assert_eq!(4, snapshot.len());
-        assert_eq!(
-            serde_yaml::Value::String("persisted".to_string()),
-            snapshot[0].0
-        );
-        assert_eq!(
-            serde_yaml::Value::String("persisted 2".to_string()),
-            snapshot[1].0
-        );
-        assert_eq!(
-            serde_yaml::Value::String("persisted 3".to_string()),
-            snapshot[2].0
-        );
-        assert_eq!(
-            serde_yaml::Value::String("persisted 5'".to_string()),
-            snapshot[3].0
-        );
+            let snapshot = events.snapshot().unwrap();
+            assert_eq!(4, snapshot.len());
+            assert_eq!(
+                serde_yaml::Value::String("persisted".to_string()),
+                snapshot[0].0
+            );
+            assert_eq!(
+                serde_yaml::Value::String("persisted 2".to_string()),
+                snapshot[1].0
+            );
+            assert_eq!(
+                serde_yaml::Value::String("persisted 3".to_string()),
+                snapshot[2].0
+            );
+            assert_eq!(
+                serde_yaml::Value::String("persisted 5'".to_string()),
+                snapshot[3].0
+            );
+        });
     }
 }
 
-fn test_file(d: &tempdir::TempDir, fname: &str, content: &str) {
-    let mut f = std::fs::File::create(d.path().join(&fname)).unwrap();
-    writeln!(f, "{}", &content).unwrap();
-    f.sync_all().unwrap();
+mod tests {
+    use super::*;
+
+    pub fn with_dir(mut foo: impl FnMut(tempdir::TempDir)) {
+        foo(tempdir::TempDir::new("").unwrap());
+    }
+
+    pub fn write_file(d: &tempdir::TempDir, fname: &str, content: &str) {
+        let mut f = std::fs::File::create(d.path().join(&fname)).unwrap();
+        writeln!(f, "{}", &content).unwrap();
+        f.sync_all().unwrap();
+    }
+
+    pub fn file_contains(d: &tempdir::TempDir, fname: &str, content: &str) {
+        let mut f = std::fs::File::create(d.path().join(&fname)).unwrap();
+        writeln!(f, "{}", &content).unwrap();
+        f.sync_all().unwrap();
+    }
 }