bpo-32604: Clean up test.support.interpreters. (gh-20926)

There were some minor adjustments needed and a few tests were missing.

https://bugs.python.org/issue32604

Author: ericsnowcurrently

Lib/test/support/interpreters.py

@@ -1,5 +1,6 @@
 """Subinterpreters High Level Module."""
 
+import time
 import _xxsubinterpreters as _interpreters
 
 # aliases:
@@ -19,165 +20,178 @@
 
 
 def create(*, isolated=True):
-    """
-    Initialize a new (idle) Python interpreter.
-    """
+    """Return a new (idle) Python interpreter."""
     id = _interpreters.create(isolated=isolated)
     return Interpreter(id, isolated=isolated)
 
 
 def list_all():
-    """
-    Get all existing interpreters.
-    """
-    return [Interpreter(id) for id in
-            _interpreters.list_all()]
+    """Return all existing interpreters."""
+    return [Interpreter(id) for id in _interpreters.list_all()]
 
 
 def get_current():
-    """
-    Get the currently running interpreter.
-    """
+    """Return the currently running interpreter."""
     id = _interpreters.get_current()
     return Interpreter(id)
 
 
 def get_main():
-    """
-    Get the main interpreter.
-    """
+    """Return the main interpreter."""
     id = _interpreters.get_main()
     return Interpreter(id)
 
 
 class Interpreter:
-    """
-    The Interpreter object represents
-    a single interpreter.
-    """
+    """A single Python interpreter."""
 
     def __init__(self, id, *, isolated=None):
+        if not isinstance(id, (int, _interpreters.InterpreterID)):
+            raise TypeError(f'id must be an int, got {id!r}')
         self._id = id
         self._isolated = isolated
 
+    def __repr__(self):
+        data = dict(id=int(self._id), isolated=self._isolated)
+        kwargs = (f'{k}={v!r}' for k, v in data.items())
+        return f'{type(self).__name__}({", ".join(kwargs)})'
+
+    def __hash__(self):
+        return hash(self._id)
+
+    def __eq__(self, other):
+        if not isinstance(other, Interpreter):
+            return NotImplemented
+        else:
+            return other._id == self._id
+
     @property
     def id(self):
         return self._id
 
     @property
     def isolated(self):
         if self._isolated is None:
+            # XXX The low-level function has not been added yet.
+            # See bpo-....
             self._isolated = _interpreters.is_isolated(self._id)
         return self._isolated
 
     def is_running(self):
-        """
-        Return whether or not the identified
-        interpreter is running.
-        """
+        """Return whether or not the identified interpreter is running."""
         return _interpreters.is_running(self._id)
 
     def close(self):
-        """
-        Finalize and destroy the interpreter.
+        """Finalize and destroy the interpreter.
 
-        Attempting to destroy the current
-        interpreter results in a RuntimeError.
+        Attempting to destroy the current interpreter results
+        in a RuntimeError.
         """
         return _interpreters.destroy(self._id)
 
     def run(self, src_str, /, *, channels=None):
-        """
-        Run the given source code in the interpreter.
+        """Run the given source code in the interpreter.
+
         This blocks the current Python thread until done.
         """
-        _interpreters.run_string(self._id, src_str)
+        _interpreters.run_string(self._id, src_str, channels)
 
 
 def create_channel():
-    """
-    Create a new channel for passing data between
-    interpreters.
-    """
+    """Return (recv, send) for a new cross-interpreter channel.
 
+    The channel may be used to pass data safely between interpreters.
+    """
     cid = _interpreters.channel_create()
-    return (RecvChannel(cid), SendChannel(cid))
+    recv, send = RecvChannel(cid), SendChannel(cid)
+    return recv, send
 
 
 def list_all_channels():
-    """
-    Get all open channels.
-    """
+    """Return a list of (recv, send) for all open channels."""
     return [(RecvChannel(cid), SendChannel(cid))
             for cid in _interpreters.channel_list_all()]
 
 
+class _ChannelEnd:
+    """The base class for RecvChannel and SendChannel."""
+
+    def __init__(self, id):
+        if not isinstance(id, (int, _interpreters.ChannelID)):
+            raise TypeError(f'id must be an int, got {id!r}')
+        self._id = id
+
+    def __repr__(self):
+        return f'{type(self).__name__}(id={int(self._id)})'
+
+    def __hash__(self):
+        return hash(self._id)
+
+    def __eq__(self, other):
+        if isinstance(self, RecvChannel):
+            if not isinstance(other, RecvChannel):
+                return NotImplemented
+        elif not isinstance(other, SendChannel):
+            return NotImplemented
+        return other._id == self._id
+
+    @property
+    def id(self):
+        return self._id
+
+
 _NOT_SET = object()
 
 
-class RecvChannel:
-    """
-    The RecvChannel object represents
-    a receiving channel.
-    """
+class RecvChannel(_ChannelEnd):
+    """The receiving end of a cross-interpreter channel."""
 
-    def __init__(self, id):
-        self._id = id
+    def recv(self, *, _sentinel=object(), _delay=10 / 1000):  # 10 milliseconds
+        """Return the next object from the channel.
 
-    def recv(self, *, _delay=10 / 1000):  # 10 milliseconds
-        """
-        Get the next object from the channel,
-        and wait if none have been sent.
-        Associate the interpreter with the channel.
+        This blocks until an object has been sent, if none have been
+        sent already.
         """
-        import time
-        sentinel = object()
-        obj = _interpreters.channel_recv(self._id, sentinel)
-        while obj is sentinel:
+        obj = _interpreters.channel_recv(self._id, _sentinel)
+        while obj is _sentinel:
             time.sleep(_delay)
-            obj = _interpreters.channel_recv(self._id, sentinel)
+            obj = _interpreters.channel_recv(self._id, _sentinel)
         return obj
 
     def recv_nowait(self, default=_NOT_SET):
-        """
-        Like recv(), but return the default
-        instead of waiting.
+        """Return the next object from the channel.
 
-        This function is blocked by a missing low-level
-        implementation of channel_recv_wait().
+        If none have been sent then return the default if one
+        is provided or fail with ChannelEmptyError.  Otherwise this
+        is the same as recv().
         """
         if default is _NOT_SET:
             return _interpreters.channel_recv(self._id)
         else:
             return _interpreters.channel_recv(self._id, default)
 
 
-class SendChannel:
-    """
-    The SendChannel object represents
-    a sending channel.
-    """
-
-    def __init__(self, id):
-        self._id = id
+class SendChannel(_ChannelEnd):
+    """The sending end of a cross-interpreter channel."""
 
     def send(self, obj):
+        """Send the object (i.e. its data) to the channel's receiving end.
+
+        This blocks until the object is received.
         """
-        Send the object (i.e. its data) to the receiving
-        end of the channel and wait. Associate the interpreter
-        with the channel.
-        """
-        import time
         _interpreters.channel_send(self._id, obj)
+        # XXX We are missing a low-level channel_send_wait().
+        # See bpo-32604 and gh-19829.
+        # Until that shows up we fake it:
         time.sleep(2)
 
     def send_nowait(self, obj):
-        """
-        Like send(), but return False if not received.
+        """Send the object to the channel's receiving end.
 
-        This function is blocked by a missing low-level
-        implementation of channel_send_wait().
+        If the object is immediately received then return True
+        (else False).  Otherwise this is the same as send().
         """
-
-        _interpreters.channel_send(self._id, obj)
-        return False
+        # XXX Note that at the moment channel_send() only ever returns
+        # None.  This should be fixed when channel_send_wait() is added.
+        # See bpo-32604 and gh-19829.
+        return _interpreters.channel_send(self._id, obj)

Lib/test/test__xxsubinterpreters.py

@@ -759,21 +759,9 @@ def test_still_running(self):
 
 class RunStringTests(TestBase):
 
-    SCRIPT = dedent("""
-        with open('{}', 'w') as out:
-            out.write('{}')
-        """)
-    FILENAME = 'spam'
-
     def setUp(self):
         super().setUp()
         self.id = interpreters.create()
-        self._fs = None
-
-    def tearDown(self):
-        if self._fs is not None:
-            self._fs.close()
-        super().tearDown()
 
     def test_success(self):
         script, file = _captured_script('print("it worked!", end="")')