diff --git a/src/lib.rs b/src/lib.rs
index 8b827ba..fd6768b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -4,5 +4,7 @@ pub mod repository;
 pub mod restore;
 pub mod source;
 
+pub mod test;
+
 mod index;
 mod repository_item;
diff --git a/src/test/assertions.rs b/src/test/assertions.rs
new file mode 100644
index 0000000..3d353ad
--- /dev/null
+++ b/src/test/assertions.rs
@@ -0,0 +1,75 @@
+use crate::error::BakareError;
+use crate::repository::Repository;
+use crate::{backup, restore};
+use std::fs::File;
+use std::io::Read;
+use std::path::Path;
+use tempfile::tempdir;
+use walkdir::WalkDir;
+
+pub fn assert_target_file_contents(restored_path: &Path, expected_contents: &str) -> Result<(), BakareError> {
+    let mut actual_contents = String::new();
+    assert!(restored_path.exists(), "Expected '{}' to be there", restored_path.display());
+    File::open(restored_path)?.read_to_string(&mut actual_contents)?;
+    assert_eq!(expected_contents, actual_contents);
+    Ok(())
+}
+
+pub fn assert_same_after_restore(source_path: &Path) -> Result<(), BakareError> {
+    let repository_path = tempdir()?.into_path();
+    let restore_target = tempdir()?.into_path();
+
+    assert_ne!(source_path, repository_path);
+    assert_ne!(repository_path, restore_target);
+
+    Repository::init(repository_path.as_path())?;
+    {
+        let mut backup_repository = Repository::open(repository_path.as_path())?;
+        let mut backup_engine = backup::Engine::new(source_path, &mut backup_repository);
+        backup_engine.backup()?;
+    }
+    {
+        let restore_repository = Repository::open(repository_path.as_path())?;
+        let restore_engine = restore::Engine::new(&restore_repository, &restore_target)?;
+        restore_engine.restore_all()?;
+    }
+
+    assert_directory_trees_have_same_contents(source_path, restore_target.as_path())?;
+    Ok(())
+}
+
+fn assert_directory_trees_have_same_contents(left: &Path, right: &Path) -> Result<(), BakareError> {
+    let left_files = get_sorted_files_recursively(left)?;
+    let right_files = get_sorted_files_recursively(right)?;
+
+    let pairs = left_files.iter().zip(right_files);
+    for (l, r) in pairs {
+        assert_eq!(l.file_name(), r.file_name());
+        let mut fl = File::open(l)?;
+        let mut fr = File::open(r)?;
+        let mut bl = vec![];
+        let mut br = vec![];
+        fl.read_to_end(&mut bl)?;
+        fr.read_to_end(&mut br)?;
+        assert_eq!(bl, br);
+    }
+    Ok(())
+}
+
+fn get_sorted_files_recursively(path: &Path) -> Result<Vec<Box<Path>>, BakareError> {
+    let walker = WalkDir::new(path).sort_by(|a, b| a.file_name().cmp(b.file_name()));
+
+    let mut result = vec![];
+
+    for maybe_entry in walker {
+        let entry = maybe_entry?;
+        if entry.path() == path {
+            continue;
+        }
+        if entry.path().is_file() {
+            result.push(Box::from(entry.path()));
+        }
+    }
+
+    Ok(result)
+}
diff --git a/src/test/mod.rs b/src/test/mod.rs
new file mode 100644
index 0000000..5324bda
--- /dev/null
+++ b/src/test/mod.rs
@@ -0,0 +1 @@
+pub mod assertions;
diff --git a/tests/system_tests.rs b/tests/system_tests.rs
index e7f7b13..33148bd 100644
--- a/tests/system_tests.rs
+++ b/tests/system_tests.rs
@@ -1,16 +1,13 @@
 use bakare::backup;
 use bakare::restore;
 
-use bakare::source::TempSource;
-
 use bakare::error::BakareError;
 use bakare::repository::Repository;
+use bakare::source::TempSource;
+
+use bakare::test::assertions::{assert_same_after_restore, assert_target_file_contents};
 use std::fs;
-use std::fs::File;
-use std::io::Read;
-use std::path::Path;
 use tempfile::tempdir;
-use walkdir::WalkDir;
 
 #[test]
 fn restore_multiple_files() -> Result<(), BakareError> {
@@ -60,20 +57,20 @@ fn restore_older_version_of_file() -> Result<(), BakareError> {
     let repository_path = tempdir()?.into_path();
     Repository::init(repository_path.as_path())?;
 
-    let relative_path_text = "some path";
-    let file_path = source.file_path(relative_path_text);
+    let source_file_relative_path = "some path";
+    let source_file_full_path = source.file_path(source_file_relative_path);
     let old_contents = "some old contents";
 
     {
         let mut backup_repository = Repository::open(repository_path.as_path())?;
         let mut backup_engine = backup::Engine::new(source.path(), &mut backup_repository);
-        source.write_text_to_file(relative_path_text, old_contents)?;
+        source.write_text_to_file(source_file_relative_path, old_contents)?;
         backup_engine.backup()?;
     }
 
     let old_version = {
         let reading_repository = Repository::open(repository_path.as_path())?;
-        let item = reading_repository.item_by_source_path(&file_path)?;
+        let item = reading_repository.item_by_source_path(&source_file_full_path)?;
         assert!(item.is_some());
         let item = item.unwrap();
         item.version().clone()
@@ -83,87 +80,20 @@ fn restore_older_version_of_file() -> Result<(), BakareError> {
         let new_contents = "totally new contents";
         let mut backup_repository = Repository::open(repository_path.as_path())?;
         let mut backup_engine = backup::Engine::new(source.path(), &mut backup_repository);
-        source.write_text_to_file(relative_path_text, new_contents)?;
+        source.write_text_to_file(source_file_relative_path, new_contents)?;
         backup_engine.backup()?;
     }
 
     let restore_repository = Repository::open(repository_path.as_path())?;
     let restore_target = tempdir()?;
     let restore_engine = restore::Engine::new(&restore_repository, &restore_target.path())?;
-    let old_item = restore_repository.item_by_source_path_and_version(&file_path, &old_version)?;
+    let old_item = restore_repository.item_by_source_path_and_version(&source_file_full_path, &old_version)?;
     restore_engine.restore(&old_item.unwrap())?;
 
-    let source_file_full_path = source.file_path(relative_path_text);
     let restored_file_path = restore_target.path().join(source_file_full_path.strip_prefix("/")?);
     assert_target_file_contents(&restored_file_path, old_contents)
 }
 
-fn assert_target_file_contents(restored_path: &Path, expected_contents: &str) -> Result<(), BakareError> {
-    let mut actual_contents = String::new();
-    assert!(restored_path.exists(), "Expected '{}' to be there", restored_path.display());
-    File::open(restored_path)?.read_to_string(&mut actual_contents)?;
-    assert_eq!(expected_contents, actual_contents);
-    Ok(())
-}
-
-fn assert_same_after_restore(source_path: &Path) -> Result<(), BakareError> {
-    let repository_path = tempdir()?.into_path();
-    let restore_target = tempdir()?.into_path();
-
-    assert_ne!(source_path, repository_path);
-    assert_ne!(repository_path, restore_target);
-
-    Repository::init(repository_path.as_path())?;
-    {
-        let mut backup_repository = Repository::open(repository_path.as_path())?;
-        let mut backup_engine = backup::Engine::new(source_path, &mut backup_repository);
-        backup_engine.backup()?;
-    }
-    {
-        let restore_repository = Repository::open(repository_path.as_path())?;
-        let restore_engine = restore::Engine::new(&restore_repository, &restore_target)?;
-        restore_engine.restore_all()?;
-    }
-
-    assert_directory_trees_have_same_contents(source_path, restore_target.as_path())?;
-    Ok(())
-}
-
-fn assert_directory_trees_have_same_contents(left: &Path, right: &Path) -> Result<(), BakareError> {
-    let left_files = get_sorted_files_recursively(left)?;
-    let right_files = get_sorted_files_recursively(right)?;
-
-    let pairs = left_files.iter().zip(right_files);
-    for (l, r) in pairs {
-        assert_eq!(l.file_name(), r.file_name());
-        let mut fl = File::open(l)?;
-        let mut fr = File::open(r)?;
-        let mut bl = vec![];
-        let mut br = vec![];
-        fl.read_to_end(&mut bl)?;
-        fr.read_to_end(&mut br)?;
-        assert_eq!(bl, br);
-    }
-    Ok(())
-}
-
-fn get_sorted_files_recursively(path: &Path) -> Result<Vec<Box<Path>>, BakareError> {
-    let walker = WalkDir::new(path).sort_by(|a, b| a.file_name().cmp(b.file_name()));
-
-    let mut result = vec![];
-
-    for maybe_entry in walker {
-        let entry = maybe_entry?;
-        if entry.path() == path {
-            continue;
-        }
-        if entry.path().is_file() {
-            result.push(Box::from(entry.path()));
-        }
-    }
-
-    Ok(result)
-}
 // TODO: restore latest version by default
 // TODO: deduplicate data
 // TODO: test that index is stored separately from data