gh-132661: Implement PEP 750 (#132662)

Co-authored-by: Lysandros Nikolaou <lisandrosnik@gmail.com>
Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
Co-authored-by: Wingy <git@wingysam.xyz>
Co-authored-by: Koudai Aono <koxudaxi@gmail.com>
Co-authored-by: Dave Peck <davepeck@gmail.com>
Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
Co-authored-by: Paul Everitt <pauleveritt@me.com>
Co-authored-by: sobolevn <mail@sobolevn.me>

Lib/test/test_string/test_templatelib.py

@@ -0,0 +1,122 @@
+import pickle
+import unittest
+from string.templatelib import Template, Interpolation
+
+from test.test_string._support import TStringBaseCase, fstring
+
+
+class TestTemplate(unittest.TestCase, TStringBaseCase):
+
+    def test_common(self):
+        self.assertEqual(type(t'').__name__, 'Template')
+        self.assertEqual(type(t'').__qualname__, 'Template')
+        self.assertEqual(type(t'').__module__, 'string.templatelib')
+
+        a = 'a'
+        i = t'{a}'.interpolations[0]
+        self.assertEqual(type(i).__name__, 'Interpolation')
+        self.assertEqual(type(i).__qualname__, 'Interpolation')
+        self.assertEqual(type(i).__module__, 'string.templatelib')
+
+    def test_basic_creation(self):
+        # Simple t-string creation
+        t = t'Hello, world'
+        self.assertIsInstance(t, Template)
+        self.assertTStringEqual(t, ('Hello, world',), ())
+        self.assertEqual(fstring(t), 'Hello, world')
+
+        # Empty t-string
+        t = t''
+        self.assertTStringEqual(t, ('',), ())
+        self.assertEqual(fstring(t), '')
+
+        # Multi-line t-string
+        t = t"""Hello,
+world"""
+        self.assertEqual(t.strings, ('Hello,\nworld',))
+        self.assertEqual(len(t.interpolations), 0)
+        self.assertEqual(fstring(t), 'Hello,\nworld')
+
+    def test_creation_interleaving(self):
+        # Should add strings on either side
+        t = Template(Interpolation('Maria', 'name', None, ''))
+        self.assertTStringEqual(t, ('', ''), [('Maria', 'name')])
+        self.assertEqual(fstring(t), 'Maria')
+
+        # Should prepend empty string
+        t = Template(Interpolation('Maria', 'name', None, ''), ' is my name')
+        self.assertTStringEqual(t, ('', ' is my name'), [('Maria', 'name')])
+        self.assertEqual(fstring(t), 'Maria is my name')
+
+        # Should append empty string
+        t = Template('Hello, ', Interpolation('Maria', 'name', None, ''))
+        self.assertTStringEqual(t, ('Hello, ', ''), [('Maria', 'name')])
+        self.assertEqual(fstring(t), 'Hello, Maria')
+
+        # Should concatenate strings
+        t = Template('Hello', ', ', Interpolation('Maria', 'name', None, ''),
+                     '!')
+        self.assertTStringEqual(t, ('Hello, ', '!'), [('Maria', 'name')])
+        self.assertEqual(fstring(t), 'Hello, Maria!')
+
+        # Should add strings on either side and in between
+        t = Template(Interpolation('Maria', 'name', None, ''),
+                     Interpolation('Python', 'language', None, ''))
+        self.assertTStringEqual(
+            t, ('', '', ''), [('Maria', 'name'), ('Python', 'language')]
+        )
+        self.assertEqual(fstring(t), 'MariaPython')
+
+    def test_template_values(self):
+        t = t'Hello, world'
+        self.assertEqual(t.values, ())
+
+        name = "Lys"
+        t = t'Hello, {name}'
+        self.assertEqual(t.values, ("Lys",))
+
+        country = "GR"
+        age = 0
+        t = t'Hello, {name}, {age} from {country}'
+        self.assertEqual(t.values, ("Lys", 0, "GR"))
+
+    def test_pickle_template(self):
+        user = 'test'
+        for template in (
+            t'',
+            t"No values",
+            t'With inter {user}',
+            t'With ! {user!r}',
+            t'With format {1 / 0.3:.2f}',
+            Template(),
+            Template('a'),
+            Template(Interpolation('Nikita', 'name', None, '')),
+            Template('a', Interpolation('Nikita', 'name', 'r', '')),
+        ):
+            for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+                with self.subTest(proto=proto, template=template):
+                    pickled = pickle.dumps(template, protocol=proto)
+                    unpickled = pickle.loads(pickled)
+
+                    self.assertEqual(unpickled.values, template.values)
+                    self.assertEqual(fstring(unpickled), fstring(template))
+
+    def test_pickle_interpolation(self):
+        for interpolation in (
+            Interpolation('Nikita', 'name', None, ''),
+            Interpolation('Nikita', 'name', 'r', ''),
+            Interpolation(1/3, 'x', None, '.2f'),
+        ):
+            for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+                with self.subTest(proto=proto, interpolation=interpolation):
+                    pickled = pickle.dumps(interpolation, protocol=proto)
+                    unpickled = pickle.loads(pickled)
+
+                    self.assertEqual(unpickled.value, interpolation.value)
+                    self.assertEqual(unpickled.expression, interpolation.expression)
+                    self.assertEqual(unpickled.conversion, interpolation.conversion)
+                    self.assertEqual(unpickled.format_spec, interpolation.format_spec)
+
+
+if __name__ == '__main__':
+    unittest.main()