BUG: more core fixes (#13665)

Fix some circular deps:
- move PromptValue into top level module bc both PromptTemplates and
OutputParsers import
- move tracer context vars to `tracers.context` and import them in
functions in `callbacks.manager`
- add core import tests

libs/core/tests/unit_tests/tracers/test_imports.py

@@ -0,0 +1,15 @@
+from langchain_core.tracers import __all__
+
+EXPECTED_ALL = [
+    "BaseTracer",
+    "EvaluatorCallbackHandler",
+    "LangChainTracer",
+    "ConsoleCallbackHandler",
+    "Run",
+    "RunLog",
+    "RunLogPatch",
+]
+
+
+def test_all_imports() -> None:
+    assert set(__all__) == set(EXPECTED_ALL)

libs/core/tests/unit_tests/tracers/test_run_collector.py

@@ -0,0 +1,16 @@
+"""Test the run collector."""
+
+import uuid
+
+from langchain_core.tracers.context import collect_runs
+from tests.unit_tests.fake.llm import FakeListLLM
+
+
+def test_collect_runs() -> None:
+    llm = FakeListLLM(responses=["hello"])
+    with collect_runs() as cb:
+        llm.predict("hi")
+        assert cb.traced_runs
+        assert len(cb.traced_runs) == 1
+        assert isinstance(cb.traced_runs[0].id, uuid.UUID)
+        assert cb.traced_runs[0].inputs == {"prompts": ["hi"]}