//! TDD tests for NCCL device handling
//! These tests define expected behavior for device validation

#![cfg(feature = "nccl")]

#[cfg(test)]
mod tests {
    use rtx_distributed::nccl_comm::validate_tensor_for_nccl;
    use rtx_tensor::{Device, Shape, Tensor};

    #[test]
    fn test_validate_cuda_tensor() {
        // Test that CUDA tensors are valid for NCCL
        if let Ok(device) = Device::cuda(0) {
            let shape = Shape::new(vec![10, 10]).unwrap();
            let tensor = Tensor::zeros(shape, &device).unwrap();

            // CUDA tensor should be valid
            assert!(validate_tensor_for_nccl(&tensor).is_ok());
        }
    }

    #[test]
    fn test_validate_cpu_tensor() {
        // Test that CPU tensors are handled properly
        let device = Device::cpu();
        let shape = Shape::new(vec![10, 10]).unwrap();
        let tensor = Tensor::zeros(shape, &device).unwrap();

        // CPU tensor validation behavior depends on impl
        // It should either succeed (will be moved to GPU) or fail with clear error
        let result = validate_tensor_for_nccl(&tensor);
        assert!(result.is_ok() || result.is_err());
    }

    #[test]
    fn test_device_pattern_matching() {
        // Test that device matching works correctly
        let device = Device::cpu();

        let result = match device {
            Device::Cuda(_) => "cuda",
            Device::Cpu => "cpu",
            _ => "other",
        };

        assert!(result == "cpu" || result == "cuda");
    }
}