From 87159dd5d09ab1d2b2776c00c81f5a94b6702686 Mon Sep 17 00:00:00 2001
From: Daniel Isaac <danielbcbs2@gmail.com>
Date: Tue, 14 Mar 2023 07:53:07 +0530
Subject: [PATCH] Backport PR #51917: Series.astype(np.integer) doesn't show
 numpy warning

---
 pandas/core/dtypes/common.py       |  8 +++++++-
 pandas/tests/dtypes/test_common.py | 10 ++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/pandas/core/dtypes/common.py b/pandas/core/dtypes/common.py
index 3be290ca2dfac..4b33fd8ed412c 100644
--- a/pandas/core/dtypes/common.py
+++ b/pandas/core/dtypes/common.py
@@ -7,6 +7,7 @@
     Any,
     Callable,
 )
+import warnings
 
 import numpy as np
 
@@ -1678,7 +1679,12 @@ def pandas_dtype(dtype) -> DtypeObj:
     # try a numpy dtype
     # raise a consistent TypeError if failed
     try:
-        npdtype = np.dtype(dtype)
+        with warnings.catch_warnings():
+            # GH#51523 - Series.astype(np.integer) doesn't show
+            # numpy deprication warning of np.integer
+            # Hence enabling DeprecationWarning
+            warnings.simplefilter("always", DeprecationWarning)
+            npdtype = np.dtype(dtype)
     except SyntaxError as err:
         # np.dtype uses `eval` which can raise SyntaxError
         raise TypeError(f"data type '{dtype}' not understood") from err
diff --git a/pandas/tests/dtypes/test_common.py b/pandas/tests/dtypes/test_common.py
index 638cfa9d82bc2..9c11bff8862c1 100644
--- a/pandas/tests/dtypes/test_common.py
+++ b/pandas/tests/dtypes/test_common.py
@@ -754,3 +754,13 @@ def test_validate_allhashable():
 
     with pytest.raises(TypeError, match="list must be a hashable type"):
         com.validate_all_hashable([], error_name="list")
+
+
+def test_pandas_dtype_numpy_warning():
+    # GH#51523
+    with tm.assert_produces_warning(
+        DeprecationWarning,
+        check_stacklevel=False,
+        match="Converting `np.integer` or `np.signedinteger` to a dtype is deprecated",
+    ):
+        pandas_dtype(np.integer)