diff --git a/src/tensor/data_buffer/buffer.rs b/src/tensor/data_buffer/buffer.rs
new file mode 100644
index 0000000..9d856ac
--- /dev/null
+++ b/src/tensor/data_buffer/buffer.rs
@@ -0,0 +1,63 @@
+use crate::data_buffer::{DataOwned, DataView};
+use crate::dtype::RawDataType;
+use std::ops::Index;
+use std::ptr::NonNull;
+
+pub trait DataBuffer: Index<usize> {
+    type DType: RawDataType;
+
+    fn len(&self) -> usize;
+
+    fn ptr(&self) -> NonNull<Self::DType>;
+
+    fn const_ptr(&self) -> *const Self::DType;
+
+    fn to_view(&self) -> DataView<Self::DType>;
+
+    // fn clone(&self) -> DataOwned<Self::DType>;
+}
+
+// Two kinds of data buffers
+// DataOwned: owns its data & responsible for cleaning it up
+// DataView: reference to data owned by another buffer
+
+impl<T: RawDataType> DataBuffer for DataOwned<T> {
+    type DType = T;
+
+    fn len(&self) -> usize {
+        self.len
+    }
+
+    fn ptr(&self) -> NonNull<T> {
+        self.ptr
+    }
+
+    fn const_ptr(&self) -> *const T {
+        self.ptr.as_ptr()
+    }
+
+    fn to_view(&self) -> DataView<T> {
+        let ptr = self.ptr;
+        let len = self.len;
+        DataView { ptr, len }
+    }
+}
+impl<T: RawDataType> DataBuffer for DataView<T> {
+    type DType = T;
+
+    fn len(&self) -> usize {
+        self.len
+    }
+
+    fn ptr(&self) -> NonNull<T> {
+        self.ptr
+    }
+
+    fn const_ptr(&self) -> *const T {
+        self.ptr.as_ptr()
+    }
+
+    fn to_view(&self) -> DataView<T> {
+        (*self).clone()
+    }
+}
diff --git a/src/tensor/data_buffer/mod.rs b/src/tensor/data_buffer/mod.rs
index ec4dce1..35fbe80 100644
--- a/src/tensor/data_buffer/mod.rs
+++ b/src/tensor/data_buffer/mod.rs
@@ -1,70 +1,56 @@
 pub(super) mod clone;
 pub(super) mod data_owned;
 pub(super) mod data_view;
+pub(super) mod buffer;
 
+pub(super) use crate::data_buffer::buffer::DataBuffer;
 pub(super) use crate::data_buffer::data_owned::DataOwned;
 pub(super) use crate::data_buffer::data_view::DataView;
 
 use crate::tensor::dtype::RawDataType;
 
 use std::ops::Index;
-use std::ptr::NonNull;
 
-pub trait DataBuffer: Index<usize> {
-    type DType: RawDataType;
+#[cfg(test)]
+mod tests {
+    use crate::data_buffer::DataOwned;
 
-    fn len(&self) -> usize;
+    #[test]
+    fn from_vector() {
+        let arr = DataOwned::from(vec![0, 50, 100]);
+        assert_eq!(arr.len(), &3);
 
-    fn ptr(&self) -> NonNull<Self::DType>;
+        let arr = DataOwned::from(vec![vec![50], vec![50], vec![50]]);
+        assert_eq!(arr.len(), &3);
 
-    fn const_ptr(&self) -> *const Self::DType;
+        let arr = DataOwned::from(vec![vec![vec![50]], vec![vec![50]]]);
+        assert_eq!(arr.len(), &2);
 
-    fn to_view(&self) -> DataView<Self::DType>;
-
-    // fn clone(&self) -> DataOwned<Self::DType>;
-}
-
-// Two kinds of data buffers
-// DataOwned: owns its data & responsible for cleaning it up
-// DataView: reference to data owned by another buffer
-
-impl<T: RawDataType> DataBuffer for DataOwned<T> {
-    type DType = T;
-
-    fn len(&self) -> usize {
-        self.len
-    }
-
-    fn ptr(&self) -> NonNull<T> {
-        self.ptr
+        let arr = DataOwned::from(vec![vec![vec![50, 50, 50]], vec![vec![50, 50, 50]]]);
+        assert_eq!(arr.len(), &6);
     }
 
-    fn const_ptr(&self) -> *const T {
-        self.ptr.as_ptr()
-    }
+    #[test]
+    fn from_array() {
+        let arr = DataOwned::from([500, 50, 100]);
+        assert_eq!(arr.len(), &3);
 
-    fn to_view(&self) -> DataView<T> {
-        let ptr = self.ptr;
-        let len = self.len;
-        DataView { ptr, len }
-    }
-}
-impl<T: RawDataType> DataBuffer for DataView<T> {
-    type DType = T;
+        let arr = DataOwned::from([[500], [50], [100]]);
+        assert_eq!(arr.len(), &3);
 
-    fn len(&self) -> usize {
-        self.len
-    }
+        let arr = DataOwned::from([[[500], [50], [30]], [[50], [0], [0]]]);
+        assert_eq!(arr.len(), &6);
 
-    fn ptr(&self) -> NonNull<T> {
-        self.ptr
+        let arr = DataOwned::from([[[50, 50]], [[50, 50]]]);
+        assert_eq!(arr.len(), &4);
     }
 
-    fn const_ptr(&self) -> *const T {
-        self.ptr.as_ptr()
-    }
+    #[test]
+    fn from_inhomogeneous_vector() {
+        let arr = DataOwned::from(vec![vec![50, 50], vec![50]]);
+        assert_eq!(arr.len(), &3);
 
-    fn to_view(&self) -> DataView<T> {
-        (*self).clone()
+        let arr = DataOwned::from(vec![vec![vec![50, 50]], vec![vec![50]], vec![vec![50]]]);
+        assert_eq!(arr.len(), &4);
     }
 }
diff --git a/tests/data_owned.rs b/tests/data_owned.rs
deleted file mode 100644
index 84764ed..0000000
--- a/tests/data_owned.rs
+++ /dev/null
@@ -1,40 +0,0 @@
-use chela::tensor::data_owned::*;
-
-#[test]
-fn from_vector() {
-    let arr = DataOwned::from(vec![0, 50, 100]);
-    assert_eq!(arr.len(), &3);
-
-    let arr = DataOwned::from(vec![vec![50], vec![50], vec![50]]);
-    assert_eq!(arr.len(), &3);
-
-    let arr = DataOwned::from(vec![vec![vec![50]], vec![vec![50]]]);
-    assert_eq!(arr.len(), &2);
-
-    let arr = DataOwned::from(vec![vec![vec![50, 50, 50]], vec![vec![50, 50, 50]]]);
-    assert_eq!(arr.len(), &6);
-}
-
-#[test]
-fn from_array() {
-    let arr = DataOwned::from([500, 50, 100]);
-    assert_eq!(arr.len(), &3);
-
-    let arr = DataOwned::from([[500], [50], [100]]);
-    assert_eq!(arr.len(), &3);
-
-    let arr = DataOwned::from([[[500], [50], [30]], [[50], [0], [0]]]);
-    assert_eq!(arr.len(), &6);
-
-    let arr = DataOwned::from([[[50, 50]], [[50, 50]]]);
-    assert_eq!(arr.len(), &4);
-}
-
-#[test]
-fn from_inhomogeneous_vector() {
-    let arr = DataOwned::from(vec![vec![50, 50], vec![50]]);
-    assert_eq!(arr.len(), &3);
-
-    let arr = DataOwned::from(vec![vec![vec![50, 50]], vec![vec![50]], vec![vec![50]]]);
-    assert_eq!(arr.len(), &4);
-}