Merge rust-bitcoin/rust-bitcoin#3884: units: Refactor Send/Sync api test

96f427a8b8 units: Refactor Send/Sync api test (Tobin C. Harding)

Pull request description:

  The `api` test for types implementing `Send` and `Sync` is part of both C-SEND-SYNC and also C-GOOD-ERR (for error types).

  Refactor the two tests into a single one and document appropriately. This is mirrors how we do it in `io/tests/api.rs`.

ACKs for top commit:
  apoelstra:
    ACK 96f427a8b84129179e86f3914be8e4712a89f660; successfully ran local tests; lgtm

Tree-SHA512: 7b24780ac2b4f73d0cad952555f005553d9b8c248da6f92c28e7e9510b58eba6c165720ded9bd2f2db19f9a19d72fe7dd333e68312f1291a47e044a94902be0b

io/tests/api.rs

@@ -129,12 +129,12 @@ fn api_all_non_error_types_have_non_empty_debug() {
     assert!(!debug.is_empty());
 }
 
-//  Types are `Send` and `Sync` where possible (C-SEND-SYNC).
 #[test]
 fn all_non_error_tyes_implement_send_sync() {
     fn assert_send<T: Send>() {}
-    assert_send::<Types>();
-
     fn assert_sync<T: Sync>() {}
+
+    //  Types are `Send` and `Sync` where possible (C-SEND-SYNC).
+    assert_send::<Types>();
     assert_sync::<Types>();
 }

units/tests/api.rs

@@ -221,16 +221,16 @@ fn api_all_non_error_types_have_non_empty_debug() {
 }
 
 #[test]
-fn send() {
+fn all_types_implement_send_sync() {
     fn assert_send<T: Send>() {}
-    assert_send::<Types>();
-    assert_send::<Errors>();
-}
-
-#[test]
-fn sync() {
     fn assert_sync<T: Sync>() {}
+
+    //  Types are `Send` and `Sync` where possible (C-SEND-SYNC).
+    assert_send::<Types>();
     assert_sync::<Types>();
+
+    // Error types should implement the Send and Sync traits (C-GOOD-ERR).
+    assert_send::<Errors>();
     assert_sync::<Errors>();
 }