From a4d54f161b6d8c730da05a60870af66a122118a2 Mon Sep 17 00:00:00 2001
From: Jonas Hoersch <jonas.hoersch@climateanalytics.org>
Date: Sun, 9 Jul 2023 14:38:33 +0200
Subject: [PATCH] Add suggested unit test for extra_stacklevel

Co-authored-by: Laurent LAPORTE <tantale.solutions@gmail.com>
---
 tests/test_deprecated.py | 62 ++++++++++++++++++++++++++++++++++------
 1 file changed, 53 insertions(+), 9 deletions(-)

diff --git a/tests/test_deprecated.py b/tests/test_deprecated.py
index ceb3b2f..0e467ae 100644
--- a/tests/test_deprecated.py
+++ b/tests/test_deprecated.py
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+import inspect
 import sys
 import warnings
 
@@ -265,16 +266,59 @@ def fun():
     assert len(warns) == 1
 
 
+def test_default_stacklevel():
+    """
+    The objective of this unit test is to ensure that the triggered warning message,
+    when invoking the 'use_foo' function, correctly indicates the line where the
+    deprecated 'foo' function is called.
+    """
+
+    @deprecated.classic.deprecated
+    def foo():
+        pass
+
+    def use_foo():
+        foo()
+
+    with warnings.catch_warnings(record=True) as warns:
+        warnings.simplefilter("always")
+        use_foo()
+
+    # Check that the warning path matches the module path
+    warn = warns[0]
+    assert warn.filename == __file__
+
+    # Check that the line number points to the first line inside 'use_foo'
+    use_foo_lineno = inspect.getsourcelines(use_foo)[1]
+    assert warn.lineno == use_foo_lineno + 1
+
+
 def test_extra_stacklevel():
-    @deprecated.classic.deprecated(version='1.2.1', reason="deprecated function", extra_stacklevel=1)
-    def inner():
+    """
+    The unit test utilizes an 'extra_stacklevel' of 1 to ensure that the warning message
+    accurately identifies the caller of the deprecated function. It verifies that when
+    the 'use_foo' function is called, the warning message correctly indicates the line
+    where the call to 'use_foo' is made.
+    """
+
+    @deprecated.classic.deprecated(extra_stacklevel=1)
+    def foo():
         pass
-        
-    def outer():
-        inner()
 
-    warnings.simplefilter("default", category=DeprecationWarning)
+    def use_foo():
+        foo()
+
+    def demo():
+        use_foo()
+
     with warnings.catch_warnings(record=True) as warns:
-        outer()
-        outer()
-    assert len(warns) == 2
+        warnings.simplefilter("always")
+        demo()
+
+    # Check that the warning path matches the module path
+    warn = warns[0]
+    assert warn.filename == __file__
+
+    # Check that the line number points to the first line inside 'demo'
+    demo_lineno = inspect.getsourcelines(demo)[1]
+    assert warn.lineno == demo_lineno + 1