diff --git a/Cargo.lock b/Cargo.lock
index df50b21..868bac2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -288,7 +288,9 @@ dependencies = [
  "memmap2",
  "pathdiff",
  "prettytable-rs",
+ "rand",
  "rayon",
+ "tempfile",
  "threadpool",
  "unicode-segmentation",
 ]
@@ -332,6 +334,22 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "34aa73646ffb006b8f5147f3dc182bd4bcb190227ce861fc4a4844bf8e3cb2c0"
 
+[[package]]
+name = "errno"
+version = "0.3.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "778e2ac28f6c47af28e4907f13ffd1e1ddbd400980a9abd7c8df189bf578a5ad"
+dependencies = [
+ "libc",
+ "windows-sys",
+]
+
+[[package]]
+name = "fastrand"
+version = "2.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "37909eebbb50d72f9059c3b6d82c0463f2ff062c9e95845c43a6c9c0355411be"
+
 [[package]]
 name = "getrandom"
 version = "0.2.15"
@@ -340,7 +358,19 @@ checksum = "c4567c8db10ae91089c99af84c68c38da3ec2f087c3f82960bcdbf3656b6f4d7"
 dependencies = [
  "cfg-if",
  "libc",
- "wasi",
+ "wasi 0.11.0+wasi-snapshot-preview1",
+]
+
+[[package]]
+name = "getrandom"
+version = "0.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "26145e563e54f2cadc477553f1ec5ee650b00862f0a58bcd12cbdc5f0ea2d2f4"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "r-efi",
+ "wasi 0.14.2+wasi-0.2.4",
 ]
 
 [[package]]
@@ -511,9 +541,9 @@ checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
 
 [[package]]
 name = "libc"
-version = "0.2.155"
+version = "0.2.174"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "97b3888a4aecf77e811145cadf6eef5901f4782c53886191b2f693f24761847c"
+checksum = "1171693293099992e19cddea4e8b849964e9846f4acee11b3948bcc337be8776"
 
 [[package]]
 name = "libredox"
@@ -525,6 +555,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "linux-raw-sys"
+version = "0.9.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cd945864f07fe9f5371a27ad7b52a172b4b499999f1d97574c9fa68373937e12"
+
 [[package]]
 name = "lock_api"
 version = "0.4.12"
@@ -612,6 +648,15 @@ version = "1.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7170ef9988bc169ba16dd36a7fa041e5c4cbeb6a35b76d4c03daded371eae7c0"
 
+[[package]]
+name = "ppv-lite86"
+version = "0.2.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85eae3c4ed2f50dcfe72643da4befc30deadb458a9b590d720cde2f2b1e97da9"
+dependencies = [
+ "zerocopy",
+]
+
 [[package]]
 name = "prettytable-rs"
 version = "0.10.0"
@@ -644,6 +689,41 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "r-efi"
+version = "5.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "69cdb34c158ceb288df11e18b4bd39de994f6657d83847bdffdbd7f346754b0f"
+
+[[package]]
+name = "rand"
+version = "0.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9fbfd9d094a40bf3ae768db9361049ace4c0e04a4fd6b359518bd7b73a73dd97"
+dependencies = [
+ "rand_chacha",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d3022b5f1df60f26e1ffddd6c66e8aa15de382ae63b3a0c1bfc0e4d3e3f325cb"
+dependencies = [
+ "ppv-lite86",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.9.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "99d9a13982dcf210057a8a78572b2217b667c3beacbf3a0d8b454f6f82837d38"
+dependencies = [
+ "getrandom 0.3.3",
+]
+
 [[package]]
 name = "rayon"
 version = "1.10.0"
@@ -679,7 +759,7 @@ version = "0.4.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bd283d9651eeda4b2a83a43c1c91b266c40fd76ecd39a50a8c630ae69dc72891"
 dependencies = [
- "getrandom",
+ "getrandom 0.2.15",
  "libredox",
  "thiserror",
 ]
@@ -701,6 +781,19 @@ version = "0.8.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7a66a03ae7c801facd77a29370b4faec201768915ac14a721ba36f20bc9c209b"
 
+[[package]]
+name = "rustix"
+version = "1.0.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c71e83d6afe7ff64890ec6b71d6a69bb8a610ab78ce364b3352876bb4c801266"
+dependencies = [
+ "bitflags 2.6.0",
+ "errno",
+ "libc",
+ "linux-raw-sys",
+ "windows-sys",
+]
+
 [[package]]
 name = "rustversion"
 version = "1.0.17"
@@ -771,6 +864,19 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "tempfile"
+version = "3.20.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e8a64e3985349f2441a1a9ef0b853f869006c3855f2cda6862a94d26ebb9d6a1"
+dependencies = [
+ "fastrand",
+ "getrandom 0.3.3",
+ "once_cell",
+ "rustix",
+ "windows-sys",
+]
+
 [[package]]
 name = "term"
 version = "0.7.0"
@@ -851,6 +957,15 @@ version = "0.11.0+wasi-snapshot-preview1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
 
+[[package]]
+name = "wasi"
+version = "0.14.2+wasi-0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9683f9a5a998d873c0d21fcbe3c083009670149a8fab228644b8bd36b2c48cb3"
+dependencies = [
+ "wit-bindgen-rt",
+]
+
 [[package]]
 name = "wasm-bindgen"
 version = "0.2.92"
@@ -1017,3 +1132,32 @@ name = "windows_x86_64_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
+
+[[package]]
+name = "wit-bindgen-rt"
+version = "0.39.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6f42320e61fe2cfd34354ecb597f86f413484a798ba44a8ca1165c58d42da6c1"
+dependencies = [
+ "bitflags 2.6.0",
+]
+
+[[package]]
+name = "zerocopy"
+version = "0.8.26"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1039dd0d3c310cf05de012d8a39ff557cb0d23087fd44cad61df08fc31907a2f"
+dependencies = [
+ "zerocopy-derive",
+]
+
+[[package]]
+name = "zerocopy-derive"
+version = "0.8.26"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9ecf5b4cc5364572d7f4c329661bcc82724222973f2cab6f050a4e5c22f75181"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
diff --git a/Cargo.toml b/Cargo.toml
index 0e0a606..4b42588 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -26,7 +26,9 @@ itertools = "0.10.5"
 memmap2 = "0.5.8"
 pathdiff = "0.2.1"
 prettytable-rs = "0.10.0"
+rand = "0.9.1"
 rayon = "1.6.1"
+tempfile = "3.20.0"
 threadpool = "1.8.1"
 unicode-segmentation = "1.10.0"
 
diff --git a/README.md b/README.md
index a6ca5cb..dc1402b 100644
--- a/README.md
+++ b/README.md
@@ -138,3 +138,4 @@ Memory: 31731MiB (~32GiB)
 - [x] add a partial hashing mode (--strict)
 - [ ] add an option to use a bloom filter for very large filesystems
 - [ ] max file path size should use the last set of duplicates
+- [ ] add unit tests
diff --git a/src/processor.rs b/src/processor.rs
index deece81..71c61bc 100644
--- a/src/processor.rs
+++ b/src/processor.rs
@@ -101,3 +101,58 @@ impl Processor {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use anyhow::Result;
+    use dashmap::DashMap;
+    use rand::Rng;
+    use std::fs::File;
+    use std::io::Write;
+    use std::sync::atomic::{AtomicBool, AtomicU64};
+    use std::sync::{Arc, Mutex};
+    use tempfile::TempDir;
+
+    use crate::fileinfo::FileInfo;
+
+    use super::Processor;
+
+    fn generate_bytes(size: usize) -> Vec<u8> {
+        let mut rng = rand::rng();
+        (0..size).map(|_| rng.random::<u8>()).collect::<Vec<u8>>()
+    }
+
+    #[test]
+    fn sizewise_sorting_normal() -> Result<()> {
+        let root = TempDir::new()?;
+        let files = [
+            (root.path().join("fileone.bin"), generate_bytes(80)),
+            (root.path().join("filetwo.bin"), generate_bytes(120)),
+        ];
+
+        for (fpath, content) in files.iter() {
+            let mut f = File::create_new(fpath)?;
+            f.write_all(content)?;
+        }
+
+        let file_queue = Arc::new(Mutex::new(
+            files
+                .iter()
+                .map(|f| FileInfo::new(f.0.clone()).unwrap())
+                .collect::<Vec<FileInfo>>(),
+        ));
+
+        let dupstore = Arc::new(DashMap::new());
+
+        Processor::sizewise(
+            Arc::new(AtomicBool::new(true)),
+            dupstore.clone(),
+            file_queue,
+            Arc::new(AtomicU64::new(0)),
+        )?;
+
+        assert_eq!(dupstore.len(), 2);
+
+        Ok(())
+    }
+}