Address PR review feedback for SessionContext utility methods

- Improve docstring examples to show actual output instead of asserts
- Use doctest +SKIP for non-deterministic session_start_time output
- Fix table_provider error mapping: outer async error is now RuntimeError
- Strengthen tests: validate RFC 3339 with fromisoformat, test both
  optimizer rule removal paths, exact string match for parse_sql_expr,
  verify enable_ident_normalization with dynamic state change

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: timsaucer

crates/core/src/context.rs

@@ -60,7 +60,7 @@ use datafusion_python_util::{
 };
 use object_store::ObjectStore;
 use pyo3::IntoPyObjectExt;
-use pyo3::exceptions::{PyKeyError, PyValueError};
+use pyo3::exceptions::{PyKeyError, PyRuntimeError, PyValueError};
 use pyo3::prelude::*;
 use pyo3::types::{PyCapsule, PyDict, PyList, PyTuple};
 use url::Url;
@@ -1088,7 +1088,9 @@ impl PySessionContext {
 
     pub fn table_provider(&self, name: &str, py: Python) -> PyResult<PyTable> {
         let provider = wait_for_future(py, self.ctx.table_provider(name))
-            .map_err(|e| PyKeyError::new_err(e.to_string()))?
+            // Outer error: runtime/async failure
+            .map_err(|e| PyRuntimeError::new_err(e.to_string()))?
+            // Inner error: table not found
             .map_err(|e| PyKeyError::new_err(e.to_string()))?;
         Ok(PyTable { table: provider })
     }

python/datafusion/context.py

@@ -1147,8 +1147,8 @@ def session_start_time(self) -> str:
 
         Examples:
             >>> ctx = SessionContext()
-            >>> start_time = ctx.session_start_time()
-            >>> assert "T" in start_time  # RFC 3339 contains a 'T' separator
+            >>> ctx.session_start_time()  # doctest: +SKIP
+            '2026-01-01T12:34:56.123456789+00:00'
         """
         return self.ctx.session_start_time()
 
@@ -1157,7 +1157,8 @@ def enable_ident_normalization(self) -> bool:
 
         Examples:
             >>> ctx = SessionContext()
-            >>> assert isinstance(ctx.enable_ident_normalization(), bool)
+            >>> ctx.enable_ident_normalization()
+            True
         """
         return self.ctx.enable_ident_normalization()
 
@@ -1175,8 +1176,8 @@ def parse_sql_expr(self, sql: str, schema: DFSchema) -> Expr:
             >>> from datafusion.common import DFSchema
             >>> ctx = SessionContext()
             >>> schema = DFSchema.empty()
-            >>> expr = ctx.parse_sql_expr("1 + 2", schema)
-            >>> assert "Int64(1) + Int64(2)" in str(expr)
+            >>> ctx.parse_sql_expr("1 + 2", schema=schema)
+            Expr(Int64(1) + Int64(2))
         """
         from datafusion.expr import Expr  # noqa: PLC0415
 

python/tests/test_context.py

@@ -552,22 +552,26 @@ def test_table_not_found(ctx):
 
 
 def test_session_start_time(ctx):
+    import datetime
+
     st = ctx.session_start_time()
     assert isinstance(st, str)
-    assert "T" in st  # RFC 3339 format
+    dt = datetime.datetime.fromisoformat(st)
+    assert dt.isoformat()
 
 
 def test_enable_ident_normalization(ctx):
-    result = ctx.enable_ident_normalization()
-    assert isinstance(result, bool)
+    assert ctx.enable_ident_normalization() is True
+    ctx.sql("SET datafusion.sql_parser.enable_ident_normalization = false")
+    assert ctx.enable_ident_normalization() is False
 
 
 def test_parse_sql_expr(ctx):
     from datafusion.common import DFSchema
 
     schema = DFSchema.empty()
     expr = ctx.parse_sql_expr("1 + 2", schema)
-    assert "Int64(1) + Int64(2)" in str(expr)
+    assert str(expr) == "Expr(Int64(1) + Int64(2))"
 
 
 def test_execute_logical_plan(ctx):
@@ -583,6 +587,7 @@ def test_refresh_catalogs(ctx):
 
 
 def test_remove_optimizer_rule(ctx):
+    assert ctx.remove_optimizer_rule("push_down_filter") is True
     assert ctx.remove_optimizer_rule("nonexistent_rule") is False