remove unused df fixture and fix parameter shadowing

Author: timsaucer

python/datafusion/functions.py

@@ -1049,8 +1049,8 @@ def greatest(*args: Expr) -> Expr:
         >>> result.collect_column("greatest")[1].as_py()
         3
     """
-    args = [arg.expr for arg in args]
-    return Expr(f.greatest(*args))
+    exprs = [arg.expr for arg in args]
+    return Expr(f.greatest(*exprs))
 
 
 def ifnull(x: Expr, y: Expr) -> Expr:
@@ -1130,8 +1130,8 @@ def least(*args: Expr) -> Expr:
         >>> result.collect_column("least")[1].as_py()
         1
     """
-    args = [arg.expr for arg in args]
-    return Expr(f.least(*args))
+    exprs = [arg.expr for arg in args]
+    return Expr(f.least(*exprs))
 
 
 def left(string: Expr, n: Expr) -> Expr:

python/tests/test_functions.py

@@ -1470,7 +1470,7 @@ def test_coalesce(df):
     )
 
 
-def test_greatest(df):
+def test_greatest():
     ctx = SessionContext()
     batch = pa.RecordBatch.from_arrays(
         [
@@ -1523,7 +1523,7 @@ def test_greatest(df):
     assert result.column(0).to_pylist() == ["banana", "cherry"]
 
 
-def test_least(df):
+def test_least():
     ctx = SessionContext()
     batch = pa.RecordBatch.from_arrays(
         [
@@ -1574,7 +1574,7 @@ def test_least(df):
     assert result.column(0).to_pylist() == ["apple", "apricot"]
 
 
-def test_nvl2(df):
+def test_nvl2():
     ctx = SessionContext()
     batch = pa.RecordBatch.from_arrays(
         [
@@ -1608,7 +1608,7 @@ def test_nvl2(df):
     assert result.column(0).to_pylist() == ["not_null", "is_null"]
 
 
-def test_ifnull(df):
+def test_ifnull():
     ctx = SessionContext()
     batch = pa.RecordBatch.from_arrays(
         [