Squashed commit of the following:

commit 37b30a8
Author: Lijun Wang <83639177+lijunwangs@users.noreply.github.com>
Date:   Thu Jul 28 17:11:42 2022 -0700

    Fixed some comments from @Ralith

quinn-proto/src/connection/streams/state.rs

@@ -812,7 +812,7 @@ impl StreamsState {
     /// again.
     pub(super) fn add_read_credits(&mut self, credits: u64) -> ShouldTransmit {
         if credits > self.receive_window_shrink_debt {
-            let net_credits = credits.saturating_sub(self.receive_window_shrink_debt);
+            let net_credits = credits - self.receive_window_shrink_debt;
             self.local_max_data = self.local_max_data.saturating_add(net_credits);
             self.receive_window_shrink_debt = 0;
         } else {
@@ -1585,73 +1585,66 @@ mod tests {
     #[test]
     fn expand_receive_window() {
         let mut server = make(Side::Server);
-        let new_receive_window = 2 * 1024 * 1024u32;
-        let explanded = server.set_receive_window(new_receive_window.into());
-        assert!(explanded);
+        let new_receive_window = 2 * server.receive_window as u32;
+        let expanded = server.set_receive_window(new_receive_window.into());
+        assert!(expanded);
         assert_eq!(server.receive_window, new_receive_window as u64);
         assert_eq!(server.local_max_data, new_receive_window as u64);
         assert_eq!(server.receive_window_shrink_debt, 0);
         let prev_local_max_data = server.local_max_data;
 
         // credit, expecting all of them added to local_max_data
         let credits = 1024u64;
-        let shuould_transmit = server.add_read_credits(credits);
+        let should_transmit = server.add_read_credits(credits);
         assert_eq!(server.receive_window_shrink_debt, 0);
         assert_eq!(server.local_max_data, prev_local_max_data + credits);
-        assert!(shuould_transmit.should_transmit());
+        assert!(should_transmit.should_transmit());
     }
 
     #[test]
     fn shrink_receive_window() {
         let mut server = make(Side::Server);
-        let new_receive_window = 1024 * 512u32;
+        let new_receive_window = server.receive_window as u32 / 2;
         let prev_local_max_data = server.local_max_data;
 
         // shrink the receive_winbow, local_max_data is not expected to be changed
         let shrink_diff = server.receive_window - new_receive_window as u64;
-        let explanded = server.set_receive_window(new_receive_window.into());
-        assert!(!explanded);
+        let expanded = server.set_receive_window(new_receive_window.into());
+        assert!(!expanded);
         assert_eq!(server.receive_window, new_receive_window as u64);
         assert_eq!(server.local_max_data, prev_local_max_data);
         assert_eq!(server.receive_window_shrink_debt, shrink_diff);
         let prev_local_max_data = server.local_max_data;
 
-        // credit, local_max_data does not change as it is absorbed by receive_window_shrink_debt
+        // credit twice, local_max_data does not change as it is absorbed by receive_window_shrink_debt
         let credits = 1024u64;
-        let expected_receive_window_shrink_debt = server.receive_window_shrink_debt - credits;
-        let shuould_transmit = server.add_read_credits(credits);
-        assert_eq!(
-            server.receive_window_shrink_debt,
-            expected_receive_window_shrink_debt
-        );
-        assert_eq!(server.local_max_data, prev_local_max_data);
-        assert!(!shuould_transmit.should_transmit());
-
-        // credit again, local_max_data does not change as it is absorbed by receive_window_shrink_debt
-        let expected_receive_window_shrink_debt = server.receive_window_shrink_debt - credits;
-        let shuould_transmit = server.add_read_credits(credits);
-        assert_eq!(
-            server.receive_window_shrink_debt,
-            expected_receive_window_shrink_debt
-        );
-        assert_eq!(server.local_max_data, prev_local_max_data);
-        assert!(!shuould_transmit.should_transmit());
+        for _ in 0..2 {
+            let expected_receive_window_shrink_debt = server.receive_window_shrink_debt - credits;
+            let should_transmit = server.add_read_credits(credits);
+            assert_eq!(
+                server.receive_window_shrink_debt,
+                expected_receive_window_shrink_debt
+            );
+            assert_eq!(server.local_max_data, prev_local_max_data);
+            assert!(!should_transmit.should_transmit());
+        }
 
         // credit again which exceeds all remaining expected_receive_window_shrink_debt
         let credits = 1024 * 512;
+        let prev_local_max_data = server.local_max_data;
         let expected_local_max_data =
             server.local_max_data + (credits - server.receive_window_shrink_debt);
-        let shuould_transmit = server.add_read_credits(credits);
+        let _should_transmit = server.add_read_credits(credits);
         assert_eq!(server.receive_window_shrink_debt, 0);
         assert_eq!(server.local_max_data, expected_local_max_data);
-        assert!(!shuould_transmit.should_transmit());
+        assert!(server.local_max_data > prev_local_max_data);
 
         // credit again, all should be added to local_max_data
         let credits = 1024 * 512;
         let expected_local_max_data = server.local_max_data + credits;
-        let shuould_transmit = server.add_read_credits(credits);
+        let should_transmit = server.add_read_credits(credits);
         assert_eq!(server.receive_window_shrink_debt, 0);
         assert_eq!(server.local_max_data, expected_local_max_data);
-        assert!(shuould_transmit.should_transmit());
+        assert!(should_transmit.should_transmit());
     }
 }