test(agent-rearrange): patch the executor the module actually uses

The three batch_run concurrency tests patch
swarms.structs.agent_rearrange.ThreadPoolExecutor, a name the module stopped
binding when kyegomez#2078 switched it to ContextThreadPoolExecutor. mock.patch raises
AttributeError before the test body runs, so all three have been failing on
master and the concurrency guarantee they exist to guard has had no working
coverage since.

Patch ContextThreadPoolExecutor instead, and drop the __import__ dance for a
plain import.

Verified with teeth: replacing batch_run's executor block with a sequential
loop fails all three. Before this change they errored identically whatever the
source did.

Author: ayaangazali

tests/structs/test_agent_rearrange.py

@@ -6,6 +6,7 @@
 import pytest
 
 from swarms import Agent, AgentRearrange
+from swarms.telemetry.otel import ContextThreadPoolExecutor
 
 
 def create_sample_agents():
@@ -1018,29 +1019,25 @@ def instrumented_run(task, img=None, *a, **kw):
         ), "Expected at least two batch_run tasks to overlap in execution"
 
     def test_threadpoolexecutor_is_used(self):
-        """Patch ThreadPoolExecutor to confirm it is invoked for each batch."""
+        """Patch the executor to confirm it is invoked for each batch."""
         pipeline = _make_pipeline("AgentA", "AgentB")
         tasks = ["t1", "t2", "t3"]
 
         with patch(
-            "swarms.structs.agent_rearrange.ThreadPoolExecutor",
-            wraps=__import__(
-                "concurrent.futures", fromlist=["ThreadPoolExecutor"]
-            ).ThreadPoolExecutor,
+            "swarms.structs.agent_rearrange.ContextThreadPoolExecutor",
+            wraps=ContextThreadPoolExecutor,
         ) as mock_tpe:
             pipeline.batch_run(tasks=tasks, batch_size=10)
             assert mock_tpe.call_count == 1
 
     def test_multiple_batches_uses_executor_per_batch(self):
-        """One ThreadPoolExecutor context-manager per batch."""
+        """One executor context-manager per batch."""
         pipeline = _make_pipeline("AgentA", "AgentB")
         tasks = [f"t{i}" for i in range(6)]
 
         with patch(
-            "swarms.structs.agent_rearrange.ThreadPoolExecutor",
-            wraps=__import__(
-                "concurrent.futures", fromlist=["ThreadPoolExecutor"]
-            ).ThreadPoolExecutor,
+            "swarms.structs.agent_rearrange.ContextThreadPoolExecutor",
+            wraps=ContextThreadPoolExecutor,
         ) as mock_tpe:
             pipeline.batch_run(tasks=tasks, batch_size=2)
             # 6 tasks / batch_size=2 -> 3 batches -> 3 executor instances
@@ -1204,13 +1201,11 @@ def test_various_batch_sizes_return_all_results(self, batch_size):
         assert len(results) == len(tasks)
 
     def test_batch_size_one_still_uses_executor(self):
-        """Even batch_size=1 should go through ThreadPoolExecutor."""
+        """Even batch_size=1 should go through the executor."""
         pipeline = _make_pipeline("AgentA", "AgentB")
         with patch(
-            "swarms.structs.agent_rearrange.ThreadPoolExecutor",
-            wraps=__import__(
-                "concurrent.futures", fromlist=["ThreadPoolExecutor"]
-            ).ThreadPoolExecutor,
+            "swarms.structs.agent_rearrange.ContextThreadPoolExecutor",
+            wraps=ContextThreadPoolExecutor,
         ) as mock_tpe:
             pipeline.batch_run(tasks=["only"], batch_size=1)
             assert mock_tpe.call_count == 1