Call str.format function in better way and update documentation string

pandas/tests/io/json/test_deprecated_kwargs.py

@@ -32,6 +32,9 @@ def test_good_kwargs():
     argument passed as keyword.
     """
     df = pd.DataFrame({"A": [2, 4, 6], "B": [3, 6, 9]}, index=[0, 1, 2])
-    assert_frame_equal(df, read_json(df.to_json(orient="split"), orient="split"))
-    assert_frame_equal(df, read_json(df.to_json(orient="columns"), orient="columns"))
-    assert_frame_equal(df, read_json(df.to_json(orient="index"), orient="index"))
+    with tm.assert_produces_warning(None):
+        assert_frame_equal(df, read_json(df.to_json(orient="split"), orient="split"))
+        assert_frame_equal(
+            df, read_json(df.to_json(orient="columns"), orient="columns")
+        )
+        assert_frame_equal(df, read_json(df.to_json(orient="index"), orient="index"))

pandas/tests/util/test_deprecate_nonkeyword_arguments.py

@@ -16,12 +16,13 @@ def f(a, b=0, c=0, d=0):
     return a + b + c + d
 
 
-def test_one_arguments():
+def test_one_argument():
     """
     Check whether no future warning is produced if one
     positional argument given.
     """
-    assert f(19) == 19
+    with tm.assert_produces_warning(None):
+        assert f(19) == 19
 
 
 def test_one_and_one_arguments():
@@ -30,15 +31,17 @@ def test_one_and_one_arguments():
     positional argument and one keyword argument are
     given.
     """
-    assert f(19, d=6) == 25
+    with tm.assert_produces_warning(None):
+        assert f(19, d=6) == 25
 
 
 def test_two_arguments():
     """
     Check whether no future warning is produced if two
     positional arguments given.
     """
-    assert f(1, 5) == 6
+    with tm.assert_produces_warning(None):
+        assert f(1, 5) == 6
 
 
 def test_two_and_two_arguments():
@@ -47,7 +50,8 @@ def test_two_and_two_arguments():
     positional arguments and two keyword arguments are
     given.
     """
-    assert f(1, 3, c=3, d=5) == 12
+    with tm.assert_produces_warning(None):
+        assert f(1, 3, c=3, d=5) == 12
 
 
 def test_three_arguments():
@@ -74,7 +78,8 @@ def g(a, b=0, c=0, d=0):
     Sum of one to four numbers, but three of them have default
     values, so may be given as keyword arguments only.
     """
-    return a + b + c + d
+    with tm.assert_produces_warning(None):
+        return a + b + c + d
 
 
 def test_one_and_three_arguments_default_allowed_args():
@@ -85,7 +90,8 @@ def test_one_and_three_arguments_default_allowed_args():
     option, meaning that all arguments with default value
     are keyword-only.
     """
-    assert g(1, b=3, c=3, d=5) == 12
+    with tm.assert_produces_warning(None):
+        assert g(1, b=3, c=3, d=5) == 12
 
 
 def test_three_arguments_default_allowed_args():

pandas/util/_decorators.py

@@ -224,7 +224,7 @@ def deprecate_nonkeyword_arguments(
         The version in which positional arguments will become
         keyword-only.
 
-    allowed_args : list, int or None, default=None
+    allowed_args : list or int, optional
         In case of list, it must be the list of names of some
         first arguments of the decorated functions that are
         OK to be given as positional arguments. In case of an
@@ -248,14 +248,20 @@ def decorate(func):
         def wrapper(*args, **kwargs):
             if isinstance(allow_args, int) and len(args) > allow_args:
                 msg = (
-                    "After version %s all arguments of %s "
-                    "except for the first %i will be keyword-only"
-                ) % (version, func.__name__, allow_args)
+                    "After Pandas version {version} all arguments of {funcname} "
+                    "except for the first {num_args} will be keyword-only"
+                ).format(version=version, funcname=func.__name__, num_args=allow_args)
             elif isinstance(allow_args, (list, tuple)) and len(args) > len(allow_args):
                 msg = (
-                    "After version %s all arguments of %s "
-                    "except for (%s) will be keyword-only"
-                ) % (version, func.__name__, ", ".join(allow_args))
+                    "After Pandas version {version} all arguments of {funcname} "
+                    "except for {first_args} will be keyword-only"
+                ).format(
+                    version=version,
+                    funcname=func.__name__,
+                    first_args="(" + ", ".join(allow_args) + ")"
+                    if len(allow_args) > 1
+                    else allow_args[0],
+                )
             else:
                 msg = None
             if msg: