[3.13] gh-104400: Add more tests to pygettext (GH-108173) (GH-126361)

(cherry picked from commit dcae5cd6ab)

Co-authored-by: Tomas R <tomas.roun8@gmail.com>

Lib/test/test_tools/i18n_data/docstrings.py

@@ -0,0 +1,41 @@
+# Test docstring extraction
+from gettext import gettext as _
+
+
+# Empty docstring
+def test(x):
+    """"""
+
+
+# Leading empty line
+def test2(x):
+
+    """docstring"""  # XXX This should be extracted but isn't.
+
+
+# XXX Multiline docstrings should be cleaned with `inspect.cleandoc`.
+def test3(x):
+    """multiline
+    docstring
+    """
+
+
+# Multiple docstrings - only the first should be extracted
+def test4(x):
+    """docstring1"""
+    """docstring2"""
+
+
+def test5(x):
+    """Hello, {}!""".format("world!")  # XXX This should not be extracted.
+
+
+# Nested docstrings
+def test6(x):
+    def inner(y):
+        """nested docstring"""  # XXX This should be extracted but isn't.
+
+
+class Outer:
+    class Inner:
+        "nested class docstring"  # XXX This should be extracted but isn't.