test out the Python Fluent implementation

The parsing step is considerably slower in Python, but if parsing
is moved out of the test function, Python wins at 45ms to Rust's 67ms
on 10,000 rounds, presumably due to the overhead of serializing to
Protobuf. Not enough of a difference to justify the inclusion of extra
dependencies and duplicating the lookup code in any case.

pylib/setup.py

@@ -23,5 +23,6 @@ setuptools.setup(
         "protobuf",
         'psutil; sys_platform == "win32"',
         'distro; sys_platform != "darwin" and sys_platform != "win32"',
+        "fluent.runtime",
     ],
 )

pylib/tests/test_collection.py

@@ -158,7 +158,37 @@ def test_translate():
     def no_uni(s: str) -> str:
         return s.replace("\u2068", "").replace("\u2069", "")
 
+    def test_backend():
         assert tr(StringsGroup.TEST, "valid-key") == "a valid key"
         assert "invalid-key" in tr(StringsGroup.TEST, "invalid-key")
         assert no_uni(tr(StringsGroup.TEST, "plural", hats=1)) == "You have 1 hat."
         assert no_uni(tr(StringsGroup.TEST, "plural", hats=2)) == "You have 2 hats."
+
+    import time
+    t = time.time()
+    test_backend()
+    print(time.time() - t)
+
+    from fluent.runtime import FluentBundle, FluentResource
+
+    test_path = os.path.join(
+        os.path.dirname(__file__), "../../rslib/tests/support/test.ftl"
+    )
+
+    def python_render(bundle, key, **kwargs):
+        try:
+            return bundle.format_pattern(bundle.get_message(key).value, kwargs)[0]
+        except:
+            return f"Missing key: {key}"
+
+    def test_python():
+        bundle = FluentBundle(["en-US"])
+        bundle.add_resource(FluentResource(open(test_path).read()))
+        assert python_render(bundle, "valid-key") == "a valid key"
+        assert "invalid-key" in python_render(bundle, "invalid-key")
+        assert no_uni(python_render(bundle, "plural", hats=1)) == "You have 1 hat."
+        assert no_uni(python_render(bundle, "plural", hats=2)) == "You have 2 hats."
+
+    t = time.time()
+    test_python()
+    print(time.time() - t)