From 22a6e68c7cf2e2e314ba3d0f154452cbf14c6d1c Mon Sep 17 00:00:00 2001
From: Jef Roosens <roosensjef@gmail.com>
Date: Mon, 19 May 2025 11:45:49 +0200
Subject: [PATCH] feat(backup): implement mutation methods and specialized
 PartialEq for State

---
 backup/src/delta.rs | 24 ++------------
 backup/src/state.rs | 76 ++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 78 insertions(+), 22 deletions(-)

diff --git a/backup/src/delta.rs b/backup/src/delta.rs
index dde906b..85b36a0 100644
--- a/backup/src/delta.rs
+++ b/backup/src/delta.rs
@@ -1,8 +1,4 @@
-use std::{
-    borrow::Borrow,
-    fmt,
-    path::{Path, PathBuf},
-};
+use std::{borrow::Borrow, fmt, path::PathBuf};
 
 use serde::{Deserialize, Serialize};
 
@@ -153,14 +149,7 @@ impl Delta {
         I: IntoIterator,
         I::Item: Into<PathBuf>,
     {
-        let dir: PathBuf = dir.into();
-        let files = files.into_iter().map(Into::into);
-
-        if let Some(dir_files) = self.added.get_mut(&dir) {
-            dir_files.extend(files);
-        } else {
-            self.added.insert(dir, files.collect());
-        }
+        self.added.append_dir(dir, files);
     }
 
     /// Wrapper around the `append_added` method for a builder-style construction of delta's
@@ -179,14 +168,7 @@ impl Delta {
         I: IntoIterator,
         I::Item: Into<PathBuf>,
     {
-        let dir: PathBuf = dir.into();
-        let files = files.into_iter().map(Into::into);
-
-        if let Some(dir_files) = self.removed.get_mut(&dir) {
-            dir_files.extend(files);
-        } else {
-            self.removed.insert(dir, files.collect());
-        }
+        self.removed.append_dir(dir, files);
     }
 
     /// Wrapper around the `append_removed` method for a builder-style construction of delta's
diff --git a/backup/src/state.rs b/backup/src/state.rs
index c0f66b9..b94370f 100644
--- a/backup/src/state.rs
+++ b/backup/src/state.rs
@@ -11,7 +11,7 @@ use crate::Delta;
 
 /// Struct that represents a current state for a backup. This struct acts as a smart pointer around
 /// a HashMap.
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
 pub struct State(HashMap<PathBuf, HashSet<PathBuf>>);
 
 impl State {
@@ -49,8 +49,52 @@ impl State {
     pub fn is_empty(&self) -> bool {
         self.0.values().all(|s| s.is_empty())
     }
+
+    pub fn append_dir<I>(&mut self, dir: impl Into<PathBuf>, files: I)
+    where
+        I: IntoIterator,
+        I::Item: Into<PathBuf>,
+    {
+        let dir = dir.into();
+        let files = files.into_iter().map(Into::into);
+
+        if let Some(dir_files) = self.0.get_mut(&dir) {
+            dir_files.extend(files);
+        } else {
+            self.0.insert(dir, files.collect());
+        }
+    }
+
+    pub fn with_dir<I>(mut self, dir: impl Into<PathBuf>, files: I) -> Self
+    where
+        I: IntoIterator,
+        I::Item: Into<PathBuf>,
+    {
+        self.append_dir(dir, files);
+        self
+    }
 }
 
+impl PartialEq for State {
+    fn eq(&self, other: &Self) -> bool {
+        let self_non_empty = self.0.values().filter(|files| !files.is_empty()).count();
+        let other_non_empty = other.0.values().filter(|files| !files.is_empty()).count();
+
+        if self_non_empty != other_non_empty {
+            return false;
+        }
+
+        // If both states have the same number of non-empty directories, then comparing each
+        // directory of one with the other will only be true if their list of non-empty directories
+        // is identical.
+        self.0
+            .iter()
+            .all(|(dir, files)| files.is_empty() || other.0.get(dir).map_or(false, |v| v == files))
+    }
+}
+
+impl Eq for State {}
+
 impl<T> From<T> for State
 where
     T: IntoIterator,
@@ -86,3 +130,33 @@ impl DerefMut for State {
         &mut self.0
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_eq() {
+        let a = State::default().with_dir("dir1", ["file1", "file2"]);
+        let b = State::default().with_dir("dir1", ["file1", "file2"]);
+
+        assert_eq!(a, b);
+
+        let b = b.with_dir("dir2", ["file3"]);
+
+        assert_ne!(a, b);
+    }
+
+    #[test]
+    fn test_eq_empty_dirs() {
+        let a = State::default().with_dir("dir1", ["file1", "file2"]);
+        let b = State::default()
+            .with_dir("dir1", ["file1", "file2"])
+            .with_dir("dir2", Vec::<PathBuf>::new());
+
+        assert_eq!(a, b);
+
+        let b = b.with_dir("dir2", ["file3"]);
+        assert_ne!(a, b);
+    }
+}