X restore test_wcfs_watch_robust after f05271b1.

wcfs/internal/wcfs_watchlink.cpp

@@ -85,7 +85,7 @@ error _WatchLink::closeWrite() {
         // XXX vvv should be ~ shutdown(TX, wlink._f), however shutdown does
         // not work for non-socket file descriptors. And even if we dup link
         // fd, and close only one used for TX, peer's RX will still be blocked
-        // ad fds are referring to one file object which stays in opened
+        // as fds are referring to one file object which stays in opened
         // state. So just use ^^^ "bye" as "TX closed" message.
         // wlink._wtx.close();
     });

wcfs/wcfs.go

@@ -1647,7 +1647,7 @@ func (wlink *WatchLink) setupWatch(ctx context.Context, foid zodb.Oid, at zodb.T
 				continue
 			}
 
-			toPin[blk], _ = f.LastBlkRev(ctx, blk, at)
+			toPin[blk], _ = f.LastBlkRev(ctx, blk, at)  // XXX err
 		}
 	}
 

wcfs/wcfs_test.py

@@ -1235,9 +1235,16 @@ def test_wcfs_watch_robust():
     wl = t.openwatch()
     wg = sync.WorkGroup(timeout())
     def _(ctx):
-        assert wl.sendReq(ctx, b"watch %s @%s" % (h(zf._p_oid), h(at1))) == \
-                "error setup watch f<%s> @%s: " % (h(zf._p_oid), h(at1)) + \
-                "pin #%d @%s: context canceled" % (2, h(at1))
+        # TODO clarify what wcfs should do if pin handler closes wlink TX:
+        #   - reply error + close, or
+        #   - just close
+        # t = when reviewing WatchLink.serve in wcfs.go
+        #assert wl.sendReq(ctx, b"watch %s @%s" % (h(zf._p_oid), h(at1))) == \
+        #        "error setup watch f<%s> @%s: " % (h(zf._p_oid), h(at1)) + \
+        #        "pin #%d @%s: context canceled" % (2, h(at1))
+        with raises(RuntimeError, match="unexpected EOF"):
+            wl.sendReq(ctx, b"watch %s @%s" % (h(zf._p_oid), h(at1)))
+
     wg.go(_)
     def _(ctx):
         req = wl.recvReq(ctx)