improvement: show return type annotations in fixtures

changelog/13676.improvement.rst

@@ -0,0 +1 @@
+Return type annotations are now shown in ``--fixtures`` and ``--fixtures-per-test``.

src/_pytest/fixtures.py

@@ -18,6 +18,7 @@
 import inspect
 import os
 from pathlib import Path
+import re
 import sys
 import types
 from typing import Any
@@ -1911,6 +1912,9 @@ def write_fixture(fixture_def: FixtureDef[object]) -> None:
             return
         prettypath = _pretty_fixture_path(invocation_dir, fixture_def.func)
         tw.write(f"{argname}", green=True)
+        ret_annotation = get_return_annotation(fixture_def.func)
+        if ret_annotation:
+            tw.write(f" -> {ret_annotation}", cyan=True)
         tw.write(f" -- {prettypath}", yellow=True)
         tw.write("\n")
         fixture_doc = inspect.getdoc(fixture_def.func)
@@ -1995,6 +1999,9 @@ def _showfixtures_main(config: Config, session: Session) -> None:
         if verbose <= 0 and argname.startswith("_"):
             continue
         tw.write(f"{argname}", green=True)
+        ret_annotation = get_return_annotation(fixturedef.func)
+        if ret_annotation:
+            tw.write(f" -> {ret_annotation}", cyan=True)
         if fixturedef.scope != "function":
             tw.write(f" [{fixturedef.scope} scope]", cyan=True)
         tw.write(f" -- {prettypath}", yellow=True)
@@ -2009,6 +2016,18 @@ def _showfixtures_main(config: Config, session: Session) -> None:
         tw.line()
 
 
+def get_return_annotation(fixture_func: Callable[..., Any]) -> str:
+    pattern = re.compile(r"\b(?:(?:<[^>]+>|[A-Za-z_]\w*)\.)+([A-Za-z_]\w*)\b")
+
+    sig = signature(fixture_func)
+    return_annotation = sig.return_annotation
+    if return_annotation is sig.empty:
+        return ""
+    if not isinstance(return_annotation, str):
+        return_annotation = inspect.formatannotation(return_annotation)
+    return pattern.sub(r"\1", return_annotation)
+
+
 def write_docstring(tw: TerminalWriter, doc: str, indent: str = "    ") -> None:
     for line in doc.split("\n"):
         tw.line(indent + line)

testing/python/fixtures.py

@@ -3582,9 +3582,9 @@ def test_show_fixtures(self, pytester: Pytester) -> None:
         result = pytester.runpytest("--fixtures")
         result.stdout.fnmatch_lines(
             [
-                "tmp_path_factory [[]session scope[]] -- .../_pytest/tmpdir.py:*",
+                "tmp_path_factory* [[]session scope[]] -- .../_pytest/tmpdir.py:*",
                 "*for the test session*",
-                "tmp_path -- .../_pytest/tmpdir.py:*",
+                "tmp_path* -- .../_pytest/tmpdir.py:*",
                 "*temporary directory*",
             ]
         )
@@ -3593,9 +3593,9 @@ def test_show_fixtures_verbose(self, pytester: Pytester) -> None:
         result = pytester.runpytest("--fixtures", "-v")
         result.stdout.fnmatch_lines(
             [
-                "tmp_path_factory [[]session scope[]] -- .../_pytest/tmpdir.py:*",
+                "tmp_path_factory* [[]session scope[]] -- .../_pytest/tmpdir.py:*",
                 "*for the test session*",
-                "tmp_path -- .../_pytest/tmpdir.py:*",
+                "tmp_path* -- .../_pytest/tmpdir.py:*",
                 "*temporary directory*",
             ]
         )
@@ -3615,7 +3615,7 @@ def arg1():
         result = pytester.runpytest("--fixtures", p)
         result.stdout.fnmatch_lines(
             """
-            *tmp_path -- *
+            *tmp_path* -- *
             *fixtures defined from*
             *arg1 -- test_show_fixtures_testmodule.py:6*
             *hello world*

testing/python/fixtures_return_annotation.py

@@ -0,0 +1,119 @@
+# mypy: allow-untyped-defs
+from __future__ import annotations
+
+from collections.abc import Callable
+from typing import Any
+
+from _pytest.config import ExitCode
+from _pytest.fixtures import get_return_annotation
+from _pytest.pytester import Pytester
+
+
+class TestGetReturnAnnotation:
+    def test_primitive_return_type(self):
+        def six() -> int:
+            return 6
+
+        assert get_return_annotation(six) == "int"
+
+    def test_compound_return_type(self):
+        def two_sixes() -> tuple[int, str]:
+            return (6, "six")
+
+        assert get_return_annotation(two_sixes) == "tuple[int, str]"
+
+    def test_callable_return_type(self):
+        def callable_return() -> Callable[..., Any]:
+            return self.test_compound_return_type
+
+        assert get_return_annotation(callable_return) == "Callable[..., Any]"
+
+    def test_no_annotation(self):
+        def no_annotation():
+            return 6
+
+        assert get_return_annotation(no_annotation) == ""
+
+    def test_none_return_type(self):
+        def none_return() -> None:
+            pass
+
+        assert get_return_annotation(none_return) == "None"
+
+    def test_custom_class_return_type(self):
+        class T:
+            pass
+
+        def class_return() -> T:
+            return T()
+
+        assert get_return_annotation(class_return) == "T"
+
+    def test_enum_return_type(self):
+        def enum_return() -> ExitCode:
+            return ExitCode(0)
+
+        assert get_return_annotation(enum_return) == "ExitCode"
+
+    def test_with_arg_annotations(self):
+        def with_args(a: Callable[[], None], b: str) -> range:
+            return range(2)
+
+        assert get_return_annotation(with_args) == "range"
+
+    def test_string_return_annotation(self):
+        def string_return_annotation() -> int:
+            return 6
+
+        assert get_return_annotation(string_return_annotation) == "int"
+
+    def test_invalid_return_type(self):
+        def bad_annotation() -> 6:  # type: ignore
+            return 6
+
+        assert get_return_annotation(bad_annotation) == "6"
+
+    def test_unobtainable_signature(self):
+        assert get_return_annotation(len) == ""
+
+
+def test_fixtures_return_annotation(pytester: Pytester) -> None:
+    p = pytester.makepyfile(
+        """
+        import pytest
+        @pytest.fixture
+        def six() -> int:
+            return 6
+    """
+    )
+    result = pytester.runpytest("--fixtures", p)
+    result.stdout.fnmatch_lines(
+        """
+        *fixtures defined from*
+        *six -> int -- test_fixtures_return_annotation.py:3*
+    """
+    )
+
+
+def test_fixtures_per_test_return_annotation(pytester: Pytester) -> None:
+    p = pytester.makepyfile(
+        """
+        import pytest
+        @pytest.fixture
+        def five() -> int:
+            return 5
+        def test_five(five):
+            pass
+    """
+    )
+
+    result = pytester.runpytest("--fixtures-per-test", p)
+    assert result.ret == 0
+
+    result.stdout.fnmatch_lines(
+        [
+            "*fixtures used by test_five*",
+            "*(test_fixtures_per_test_return_annotation.py:6)*",
+            "five -> int -- test_fixtures_per_test_return_annotation.py:3",
+        ]
+    )