Fix the npy read function and add some testing. (#1080)

candle-core/tests/serialization_tests.rs

@@ -0,0 +1,24 @@
+use candle_core::{DType, Result, Tensor};
+
+#[test]
+fn npy() -> Result<()> {
+    let npy = Tensor::read_npy("tests/test.npy")?;
+    assert_eq!(
+        npy.to_dtype(DType::U8)?.to_vec1::<u8>()?,
+        [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+    );
+    Ok(())
+}
+
+#[test]
+fn npz() -> Result<()> {
+    let npz = Tensor::read_npz("tests/test.npz")?;
+    assert_eq!(npz.len(), 2);
+    assert_eq!(npz[0].0, "x");
+    assert_eq!(npz[1].0, "x_plus_one");
+    assert_eq!(
+        npz[1].1.to_dtype(DType::U8)?.to_vec1::<u8>()?,
+        [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
+    );
+    Ok(())
+}