[rs] Merge #184

184: added test to hello-compute example r=kvark a=emmetthebarnraiser

I wasn't exactly sure of the proper way to test async stuff, but this is a strategy that seemed to work for me. Let me know if there is anything you would like me to change, or if this isn't something that you would like to add to the examples!

Co-authored-by: Brian Frazho <befrazho@gmail.com>

wgpu/examples/hello-compute/main.rs

@@ -13,6 +13,10 @@ async fn run() {
         .map(|s| u32::from_str(&s).expect("You must pass a list of positive integers!"))
         .collect();
 
+    println!("Times: {:?}", execute_gpu(numbers).await);
+}
+
+async fn execute_gpu(numbers: Vec<u32>) -> Vec<u32> {
     let slice_size = numbers.len() * std::mem::size_of::<u32>();
     let size = slice_size as wgpu::BufferAddress;
 
@@ -92,18 +96,38 @@ async fn run() {
     encoder.copy_buffer_to_buffer(&storage_buffer, 0, &staging_buffer, 0, size);
 
     queue.submit(&[encoder.finish()]);
-
     if let Ok(mapping) = staging_buffer.map_read(0u64, size).await {
-        let times : Box<[u32]> = mapping
+        mapping
             .as_slice()
             .chunks_exact(4)
             .map(|b| u32::from_ne_bytes(b.try_into().unwrap()))
-            .collect();
-
-        println!("Times: {:?}", times);
+            .collect()
+    } else {
+        panic!("failed to run compute on gpu!")
     }
 }
 
 fn main() {
     futures::executor::block_on(run());
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_compute_1(){
+        let input = vec!(1, 2, 3, 4);
+        futures::executor::block_on(assert_execute_gpu(input, vec!(0, 1, 7, 2)));
+    }
+
+    #[test]
+    fn test_compute_2(){
+        let input = vec!(5, 23, 10, 9);
+        futures::executor::block_on(assert_execute_gpu(input, vec!(5, 15, 6, 19)));
+    }
+
+    async fn assert_execute_gpu(input: Vec<u32>, expected: Vec<u32>){
+        assert_eq!(execute_gpu(input).await, expected);
+    }
+}