diff --git a/src/tests.rs b/src/tests.rs
index 4edb809..5495151 100644
--- a/src/tests.rs
+++ b/src/tests.rs
@@ -4,6 +4,7 @@
 mod tests {
     use tempfile::tempdir;
     use std::io::Write;
+    use std::str::FromStr;
     
     // Import the modules we need for testing
     use keep::compression_engine::{self, CompressionType};
@@ -11,126 +12,223 @@ mod tests {
     use keep::compression_engine::lz4::CompressionEngineLZ4;
     use keep::compression_engine::none::CompressionEngineNone;
 
-    #[test]
-    fn test_compression_engine_gzip() {
-        let test_data = b"test compression data";
-        
-        // Create a temporary file
-        let dir = tempdir().expect("Failed to create temporary directory");
-        let file_path = dir.path().join("test.gz");
-        
-        // Test compression engine
-        let engine = CompressionEngineGZip::new();
-        assert!(engine.is_supported());
-        
-        // Create compressed file
-        {
-            let mut writer = engine.create(file_path.clone()).expect("Failed to create writer");
-            writer.write_all(test_data).expect("Failed to write data");
-            // Writer is dropped here, which should finish the compression
+    mod compression_tests {
+        use super::*;
+
+        #[test]
+        fn test_compression_engine_gzip() {
+            let test_data = b"test compression data";
+            
+            // Create a temporary file
+            let dir = tempdir().expect("Failed to create temporary directory");
+            let file_path = dir.path().join("test.gz");
+            
+            // Test compression engine
+            let engine = CompressionEngineGZip::new();
+            assert!(engine.is_supported());
+            
+            // Create compressed file
+            {
+                let mut writer = engine.create(file_path.clone()).expect("Failed to create writer");
+                writer.write_all(test_data).expect("Failed to write data");
+                // Writer is dropped here, which should finish the compression
+            }
+            
+            // Read compressed file
+            let mut reader = engine.open(file_path).expect("Failed to open reader");
+            let mut decompressed = Vec::new();
+            std::io::copy(&mut reader, &mut decompressed).expect("Failed to read data");
+            
+            assert_eq!(test_data, decompressed.as_slice());
         }
-        
-        // Read compressed file
-        let mut reader = engine.open(file_path).expect("Failed to open reader");
-        let mut decompressed = Vec::new();
-        std::io::copy(&mut reader, &mut decompressed).expect("Failed to read data");
-        
-        assert_eq!(test_data, decompressed.as_slice());
-    }
 
-    #[test]
-    fn test_compression_engine_lz4() {
-        let test_data = b"test compression data";
-        
-        // Create a temporary file
-        let dir = tempdir().expect("Failed to create temporary directory");
-        let file_path = dir.path().join("test.lz4");
-        
-        // Test compression engine
-        let engine = CompressionEngineLZ4::new();
-        
-        // Create compressed file
-        {
-            let mut writer = engine.create(file_path.clone()).expect("Failed to create writer");
-            writer.write_all(test_data).expect("Failed to write data");
+        #[test]
+        fn test_compression_engine_gzip_empty_data() {
+            let test_data = b"";
+            
+            // Create a temporary file
+            let dir = tempdir().expect("Failed to create temporary directory");
+            let file_path = dir.path().join("test_empty.gz");
+            
+            // Test compression engine
+            let engine = CompressionEngineGZip::new();
+            
+            // Create compressed file
+            {
+                let mut writer = engine.create(file_path.clone()).expect("Failed to create writer");
+                writer.write_all(test_data).expect("Failed to write data");
+            }
+            
+            // Read compressed file
+            let mut reader = engine.open(file_path).expect("Failed to open reader");
+            let mut decompressed = Vec::new();
+            std::io::copy(&mut reader, &mut decompressed).expect("Failed to read data");
+            
+            assert_eq!(test_data, decompressed.as_slice());
         }
-        
-        // Read compressed file
-        let mut reader = engine.open(file_path).expect("Failed to open reader");
-        let mut decompressed = Vec::new();
-        std::io::copy(&mut reader, &mut decompressed).expect("Failed to read data");
-        
-        assert_eq!(test_data, decompressed.as_slice());
-    }
 
-    #[test]
-    fn test_compression_engine_none() {
-        let test_data = b"test compression data";
-        
-        // Create a temporary file
-        let dir = tempdir().expect("Failed to create temporary directory");
-        let file_path = dir.path().join("test.dat");
-        
-        // Test compression engine
-        let engine = CompressionEngineNone::new();
-        
-        // Create file
-        {
-            let mut writer = engine.create(file_path.clone()).expect("Failed to create writer");
-            writer.write_all(test_data).expect("Failed to write data");
+        #[test]
+        fn test_compression_engine_lz4() {
+            let test_data = b"test compression data";
+            
+            // Create a temporary file
+            let dir = tempdir().expect("Failed to create temporary directory");
+            let file_path = dir.path().join("test.lz4");
+            
+            // Test compression engine
+            let engine = CompressionEngineLZ4::new();
+            
+            // Create compressed file
+            {
+                let mut writer = engine.create(file_path.clone()).expect("Failed to create writer");
+                writer.write_all(test_data).expect("Failed to write data");
+            }
+            
+            // Read compressed file
+            let mut reader = engine.open(file_path).expect("Failed to open reader");
+            let mut decompressed = Vec::new();
+            std::io::copy(&mut reader, &mut decompressed).expect("Failed to read data");
+            
+            assert_eq!(test_data, decompressed.as_slice());
+        }
+
+        #[test]
+        fn test_compression_engine_lz4_large_data() {
+            let test_data: Vec<u8> = (0..10000).map(|i| (i % 256) as u8).collect();
+            
+            // Create a temporary file
+            let dir = tempdir().expect("Failed to create temporary directory");
+            let file_path = dir.path().join("test_large.lz4");
+            
+            // Test compression engine
+            let engine = CompressionEngineLZ4::new();
+            
+            // Create compressed file
+            {
+                let mut writer = engine.create(file_path.clone()).expect("Failed to create writer");
+                writer.write_all(&test_data).expect("Failed to write data");
+            }
+            
+            // Read compressed file
+            let mut reader = engine.open(file_path).expect("Failed to open reader");
+            let mut decompressed = Vec::new();
+            std::io::copy(&mut reader, &mut decompressed).expect("Failed to read data");
+            
+            assert_eq!(test_data, decompressed);
+        }
+
+        #[test]
+        fn test_compression_engine_none() {
+            let test_data = b"test compression data";
+            
+            // Create a temporary file
+            let dir = tempdir().expect("Failed to create temporary directory");
+            let file_path = dir.path().join("test.dat");
+            
+            // Test compression engine
+            let engine = CompressionEngineNone::new();
+            
+            // Create file
+            {
+                let mut writer = engine.create(file_path.clone()).expect("Failed to create writer");
+                writer.write_all(test_data).expect("Failed to write data");
+            }
+            
+            // Read file
+            let mut reader = engine.open(file_path).expect("Failed to open reader");
+            let mut data = Vec::new();
+            std::io::copy(&mut reader, &mut data).expect("Failed to read data");
+            
+            assert_eq!(test_data, data.as_slice());
+        }
+
+        #[test]
+        fn test_compression_engine_none_empty_data() {
+            let test_data = b"";
+            
+            // Create a temporary file
+            let dir = tempdir().expect("Failed to create temporary directory");
+            let file_path = dir.path().join("test_empty.dat");
+            
+            // Test compression engine
+            let engine = CompressionEngineNone::new();
+            
+            // Create file
+            {
+                let mut writer = engine.create(file_path.clone()).expect("Failed to create writer");
+                writer.write_all(test_data).expect("Failed to write data");
+            }
+            
+            // Read file
+            let mut reader = engine.open(file_path).expect("Failed to open reader");
+            let mut data = Vec::new();
+            std::io::copy(&mut reader, &mut data).expect("Failed to read data");
+            
+            assert_eq!(test_data, data.as_slice());
         }
-        
-        // Read file
-        let mut reader = engine.open(file_path).expect("Failed to open reader");
-        let mut data = Vec::new();
-        std::io::copy(&mut reader, &mut data).expect("Failed to read data");
-        
-        assert_eq!(test_data, data.as_slice());
     }
 
-    #[test]
-    fn test_compression_engine_factory() {
-        // Test getting different compression engines
-        let lz4_engine = compression_engine::get_compression_engine(
-            CompressionType::LZ4
-        ).expect("Failed to get LZ4 engine");
-        assert!(lz4_engine.is_supported());
-        
-        let gzip_engine = compression_engine::get_compression_engine(
-            CompressionType::GZip
-        ).expect("Failed to get GZip engine");
-        assert!(gzip_engine.is_supported());
-        
-        let none_engine = compression_engine::get_compression_engine(
-            CompressionType::None
-        ).expect("Failed to get None engine");
-        assert!(none_engine.is_supported());
-    }
+    mod compression_type_tests {
+        use super::*;
 
-    #[test]
-    fn test_default_compression_type() {
-        let default = compression_engine::default_compression_type();
-        // The default should be a supported compression type
-        let engine = compression_engine::get_compression_engine(default)
-            .expect("Failed to get default compression engine");
-        assert!(engine.is_supported());
-    }
+        #[test]
+        fn test_compression_engine_factory() {
+            // Test getting different compression engines
+            let lz4_engine = compression_engine::get_compression_engine(
+                CompressionType::LZ4
+            ).expect("Failed to get LZ4 engine");
+            assert!(lz4_engine.is_supported());
+            
+            let gzip_engine = compression_engine::get_compression_engine(
+                CompressionType::GZip
+            ).expect("Failed to get GZip engine");
+            assert!(gzip_engine.is_supported());
+            
+            let none_engine = compression_engine::get_compression_engine(
+                CompressionType::None
+            ).expect("Failed to get None engine");
+            assert!(none_engine.is_supported());
+        }
 
-    #[test]
-    fn test_compression_type_display() {
-        assert_eq!(format!("{}", CompressionType::LZ4), "LZ4");
-        assert_eq!(format!("{}", CompressionType::GZip), "GZip");
-        assert_eq!(format!("{}", CompressionType::None), "None");
-    }
+        #[test]
+        fn test_compression_engine_factory_invalid() {
+            // Test that we get an error for unsupported compression types
+            // This test assumes that any invalid type would return an error
+            // In practice, you might want to add an Invalid variant to CompressionType
+        }
 
-    #[test]
-    fn test_compression_type_from_str() {
-        use std::str::FromStr;
-        assert_eq!(CompressionType::from_str("lz4").unwrap(), CompressionType::LZ4);
-        assert_eq!(CompressionType::from_str("gzip").unwrap(), CompressionType::GZip);
-        assert_eq!(CompressionType::from_str("none").unwrap(), CompressionType::None);
-        // Test case insensitivity
-        assert_eq!(CompressionType::from_str("LZ4").unwrap(), CompressionType::LZ4);
-        assert_eq!(CompressionType::from_str("GZIP").unwrap(), CompressionType::GZip);
+        #[test]
+        fn test_default_compression_type() {
+            let default = compression_engine::default_compression_type();
+            // The default should be a supported compression type
+            let engine = compression_engine::get_compression_engine(default)
+                .expect("Failed to get default compression engine");
+            assert!(engine.is_supported());
+        }
+
+        #[test]
+        fn test_compression_type_display() {
+            assert_eq!(format!("{}", CompressionType::LZ4), "LZ4");
+            assert_eq!(format!("{}", CompressionType::GZip), "GZip");
+            assert_eq!(format!("{}", CompressionType::None), "None");
+        }
+
+        #[test]
+        fn test_compression_type_from_str() {
+            assert_eq!(CompressionType::from_str("lz4").unwrap(), CompressionType::LZ4);
+            assert_eq!(CompressionType::from_str("gzip").unwrap(), CompressionType::GZip);
+            assert_eq!(CompressionType::from_str("none").unwrap(), CompressionType::None);
+            // Test case insensitivity
+            assert_eq!(CompressionType::from_str("LZ4").unwrap(), CompressionType::LZ4);
+            assert_eq!(CompressionType::from_str("GZIP").unwrap(), CompressionType::GZip);
+            assert_eq!(CompressionType::from_str("NONE").unwrap(), CompressionType::None);
+        }
+
+        #[test]
+        fn test_compression_type_from_str_invalid() {
+            assert!(CompressionType::from_str("invalid").is_err());
+            assert!(CompressionType::from_str("").is_err());
+            assert!(CompressionType::from_str("xz").is_err());
+        }
     }
 }