Add timeouts around some context test bodies

Since with my in-index runtime-port to our native msg-spec it seems
these ones are hanging B(

- `test_one_end_stream_not_opened()`
- `test_maybe_allow_overruns_stream()`

Tossing in some `trio.fail_after()`s seems to at least gnab them as
failures B)

tests/test_context_stream_semantics.py

@@ -6,6 +6,7 @@ sync-opening a ``tractor.Context`` beforehand.
 
 '''
 from itertools import count
+import math
 import platform
 from pprint import pformat
 from typing import (
@@ -872,7 +873,7 @@ def test_one_end_stream_not_opened(
                 enable_modules=[__name__],
             )
 
-            with trio.fail_after(1):
+            with trio.fail_after(0.8):
                 async with portal.open_context(
                     entrypoint,
                 ) as (ctx, sent):
@@ -1059,54 +1060,63 @@ def test_maybe_allow_overruns_stream(
                 loglevel=loglevel,
                 debug_mode=debug_mode,
             )
-            seq = list(range(10))
-            async with portal.open_context(
-                echo_back_sequence,
-                seq=seq,
-                wait_for_cancel=cancel_ctx,
-                be_slow=(slow_side == 'child'),
-                allow_overruns_side=allow_overruns_side,
 
-            ) as (ctx, sent):
-                assert sent is None
+            # stream-sequence batch info with send delay to determine
+            # approx timeout determining whether test has hung.
+            total_batches: int = 2
+            num_items: int = 10
+            seq = list(range(num_items))
+            parent_send_delay: float = 0.16
+            timeout: float = math.ceil(
+                total_batches * num_items * parent_send_delay
+            )
+            with trio.fail_after(timeout):
+                async with portal.open_context(
+                    echo_back_sequence,
+                    seq=seq,
+                    wait_for_cancel=cancel_ctx,
+                    be_slow=(slow_side == 'child'),
+                    allow_overruns_side=allow_overruns_side,
 
-                async with ctx.open_stream(
-                    msg_buffer_size=1 if slow_side == 'parent' else None,
-                    allow_overruns=(allow_overruns_side in {'parent', 'both'}),
-                ) as stream:
+                ) as (ctx, sent):
+                    assert sent is None
 
-                    total_batches: int = 2
-                    for _ in range(total_batches):
-                        for msg in seq:
-                            # print(f'root tx {msg}')
-                            await stream.send(msg)
-                            if slow_side == 'parent':
-                                # NOTE: we make the parent slightly
-                                # slower, when it is slow, to make sure
-                                # that in the overruns everywhere case
-                                await trio.sleep(0.16)
+                    async with ctx.open_stream(
+                        msg_buffer_size=1 if slow_side == 'parent' else None,
+                        allow_overruns=(allow_overruns_side in {'parent', 'both'}),
+                    ) as stream:
 
-                        batch = []
-                        async for msg in stream:
-                            print(f'root rx {msg}')
-                            batch.append(msg)
-                            if batch == seq:
-                                break
+                        for _ in range(total_batches):
+                            for msg in seq:
+                                # print(f'root tx {msg}')
+                                await stream.send(msg)
+                                if slow_side == 'parent':
+                                    # NOTE: we make the parent slightly
+                                    # slower, when it is slow, to make sure
+                                    # that in the overruns everywhere case
+                                    await trio.sleep(parent_send_delay)
+
+                            batch = []
+                            async for msg in stream:
+                                print(f'root rx {msg}')
+                                batch.append(msg)
+                                if batch == seq:
+                                    break
+
+                    if cancel_ctx:
+                        # cancel the remote task
+                        print('Requesting `ctx.cancel()` in parent!')
+                        await ctx.cancel()
+
+                res: str|ContextCancelled = await ctx.result()
 
                 if cancel_ctx:
-                    # cancel the remote task
-                    print('Requesting `ctx.cancel()` in parent!')
-                    await ctx.cancel()
+                    assert isinstance(res, ContextCancelled)
+                    assert tuple(res.canceller) == current_actor().uid
 
-            res: str|ContextCancelled = await ctx.result()
-
-            if cancel_ctx:
-                assert isinstance(res, ContextCancelled)
-                assert tuple(res.canceller) == current_actor().uid
-
-            else:
-                print(f'RX ROOT SIDE RESULT {res}')
-                assert res == 'yo'
+                else:
+                    print(f'RX ROOT SIDE RESULT {res}')
+                    assert res == 'yo'
 
             # cancel the daemon
             await portal.cancel_actor()

tractor/msg/_codec.py

@@ -438,8 +438,8 @@ _ctxvar_MsgCodec: MsgCodec = RunVar(
     'msgspec_codec',
 
     # TODO: move this to our new `Msg`-spec!
-    # default=_def_msgspec_codec,
-    default=_def_tractor_codec,
+    default=_def_msgspec_codec,
+    # default=_def_tractor_codec,
 )