Add _test_pg helper (#45)

* Add _test_pg helper

* update CONTRIBUTING.md

CONTRIBUTING.md

@@ -67,6 +67,20 @@ lintrunner -a
 
 ### Tests
 
+We use `pytest` as our testing framework. To execute a specific test, use the following command:
+
+```sh
+pytest torchft/process_group_test.py -k test_device_mesh
+```
+
+To run the Rust tests run:
+
+```sh
+cargo test
+```
+
+To run the entire suite of tests:
+
 ```sh
 $ scripts/test.sh
 ```

torchft/process_group_test.py

@@ -6,21 +6,34 @@
 
 import os
 from concurrent.futures import ThreadPoolExecutor
-from typing import Tuple
+from typing import Any, Dict, Tuple
 from unittest import TestCase, skipUnless
 from unittest.mock import Mock
 
 import torch
 import torch.distributed as dist
 from torch import nn
-from torch._C._distributed_c10d import _resolve_process_group
-from torch.distributed import ReduceOp, TCPStore, Work, _functional_collectives
+from torch._C._distributed_c10d import (
+    AllgatherOptions,
+    AllreduceOptions,
+    BroadcastOptions,
+    ReduceOp,
+    _resolve_process_group,
+)
+from torch.distributed import (
+    ReduceOp,
+    TCPStore,
+    Work,
+    _functional_collectives,
+    get_world_size,
+)
 from torch.distributed.device_mesh import init_device_mesh
 
 from torchft.manager import Manager
 from torchft.process_group import (
     ErrorSwallowingProcessGroupWrapper,
     ManagedProcessGroup,
+    ProcessGroup,
     ProcessGroupBabyGloo,
     ProcessGroupBabyNCCL,
     ProcessGroupDummy,
@@ -41,6 +54,56 @@ def dummy_init_pg() -> None:
         )
 
 
+def _test_pg(
+    pg: ProcessGroup,
+    example_tensor: torch.Tensor = torch.randn((2, 3), dtype=torch.float32),
+) -> Dict[str, dist._Work]:
+    """
+    Helper function to test a set of collective operations on a given process group.
+    """
+
+    shape: torch.Size = example_tensor.shape
+    dtype: torch.dtype = example_tensor.dtype
+
+    # Create some dummy tensors for testing
+    input_tensor = example_tensor.clone()
+    output_tensors = [
+        [torch.empty_like(input_tensor) for _ in range(get_world_size(pg))]
+    ]
+    tensor_list = [torch.empty_like(input_tensor)]
+
+    def check_tensors(arg: Any) -> None:  # pyre-ignore[2]
+        """Recursively check tensors for expected shape and dtype."""
+        if isinstance(arg, torch.Tensor):
+            assert arg.dtype == dtype, f"Output dtype mismatch: {arg.dtype} != {dtype}"
+            assert arg.shape == shape, f"Output shape mismatch: {arg.shape} != {shape}"
+        elif isinstance(arg, (list, tuple)):
+            for item in arg:
+                check_tensors(item)
+
+    # Test collectives
+    collectives = {
+        "allreduce": ([input_tensor], AllreduceOptions()),
+        "allgather": (output_tensors, [input_tensor], AllgatherOptions()),
+        "broadcast": (tensor_list, BroadcastOptions()),
+        "broadcast_one": (input_tensor, 0),
+    }
+    works: Dict[str, dist._Work] = {}
+    for coll_str, args in collectives.items():
+        coll = getattr(pg, coll_str)
+        work = coll(*args)
+        works[coll_str] = work
+        work.wait()
+        fut = work.get_future()
+        fut.wait()
+
+        # Check that all tensor arguments have the expected shapes and dtypes
+        check_tensors(args)
+
+    print(works)
+    return works
+
+
 class ProcessGroupTest(TestCase):
     def test_gloo(self) -> None:
         store = TCPStore(
@@ -53,11 +116,7 @@ def test_gloo(self) -> None:
 
         self.assertEqual(pg.size(), 1)
 
-        at = torch.tensor([2])
-
-        a_work = pg.allreduce([at], ReduceOp.SUM)
-        a_work.wait()
-        a_work.get_future().wait()
+        _test_pg(pg)
 
         m = nn.Linear(3, 4)
         m = torch.nn.parallel.DistributedDataParallel(m, process_group=pg)
@@ -77,10 +136,7 @@ def test_nccl(self) -> None:
 
         self.assertEqual(pg.size(), 1)
 
-        at = torch.tensor([2], device=device)
-        a_work = pg.allreduce([at], ReduceOp.SUM)
-        a_work.wait()
-        a_work.get_future().wait()
+        _test_pg(pg, torch.tensor([2], device=device))
 
         m = nn.Linear(3, 4).to(device)
         m = torch.nn.parallel.DistributedDataParallel(m, process_group=pg)
@@ -90,9 +146,7 @@ def test_nccl(self) -> None:
         store_addr = f"localhost:{store.port}/prefix2"
         pg.configure(store_addr, 0, 1)
 
-        at = torch.tensor([2], device=device)
-        a_work = pg.allreduce([at], ReduceOp.SUM)
-        a_work.wait()
+        _test_pg(pg, torch.tensor([2], device=device))
 
         torch.cuda.synchronize()
 
@@ -220,22 +274,16 @@ def test_error_swallowing_process_group_wrapper(self) -> None:
         wrapper = ErrorSwallowingProcessGroupWrapper(pg)
         self.assertIs(wrapper.parent, pg)
 
-        t = torch.zeros(10)
-        work = wrapper.allreduce([t], ReduceOp.SUM)
-        self.assertIsInstance(work, _ErrorSwallowingWork)
-        work.wait()
-        fut = work.get_future()
-        fut.wait()
+        works = _test_pg(wrapper)
+        self.assertIsInstance(list(works.values())[0], _ErrorSwallowingWork)
 
         err = RuntimeError("test")
         wrapper.report_error(err)
         self.assertEqual(wrapper.error(), err)
 
-        work = wrapper.allreduce([t], ReduceOp.SUM)
-        self.assertIsInstance(work, _DummyWork)
-        work.wait()
-        fut = work.get_future()
-        fut.wait()
+        works = _test_pg(wrapper)
+        for work in works.values():
+            self.assertIsInstance(work, _DummyWork)
 
     def test_managed_process_group(self) -> None:
         manager = Mock(spec=Manager)
@@ -246,12 +294,8 @@ def test_managed_process_group(self) -> None:
 
         self.assertEqual(pg.size(), 123)
 
-        t = torch.zeros(10)
-        work = pg.allreduce([t], ReduceOp.SUM)
-        self.assertIsInstance(work, _ManagedWork)
-        work.wait()
-        fut = work.get_future()
-        fut.wait()
+        works = _test_pg(pg)
+        self.assertIsInstance(list(works.values())[0], _ManagedWork)
 
         self.assertEqual(manager.report_error.call_count, 0)
         self.assertEqual(manager.wrap_future.call_count, 1)