Add some basic test.

tests/tensor_tests.rs

@@ -0,0 +1,10 @@
+use candle::{DType, Device, Result, Tensor};
+
+#[test]
+fn add() -> Result<()> {
+    let tensor = Tensor::zeros(&[5, 2], DType::F32, Device::Cpu);
+    let (dim1, dim2) = tensor.shape2()?;
+    assert_eq!(dim1, 5);
+    assert_eq!(dim2, 2);
+    Ok(())
+}