Fix required_plugins with prereleases (#8469)

* Fix required_plugins with prereleases

Fixes #8456

* Fix existing tests

* Update changelog/8456.bugfix.rst

Co-authored-by: Bruno Oliveira <nicoddemus@gmail.com>

Co-authored-by: Bruno Oliveira <nicoddemus@gmail.com>

changelog/8456.bugfix.rst

@@ -0,0 +1 @@
+The :confval:`required_plugins` config option now works correctly when pre-releases of plugins are installed, rather than falsely claiming that those plugins aren't installed at all.

src/_pytest/config/__init__.py

@@ -1270,14 +1270,16 @@ class Config:
         missing_plugins = []
         for required_plugin in required_plugins:
             try:
-                spec = Requirement(required_plugin)
+                req = Requirement(required_plugin)
             except InvalidRequirement:
                 missing_plugins.append(required_plugin)
                 continue
 
-            if spec.name not in plugin_dist_info:
+            if req.name not in plugin_dist_info:
                 missing_plugins.append(required_plugin)
-            elif Version(plugin_dist_info[spec.name]) not in spec.specifier:
+            elif not req.specifier.contains(
+                Version(plugin_dist_info[req.name]), prereleases=True
+            ):
                 missing_plugins.append(required_plugin)
 
         if missing_plugins:

testing/test_config.py

@@ -309,13 +309,14 @@ class TestParseIni:
         result.stdout.no_fnmatch_line("*PytestConfigWarning*")
 
     @pytest.mark.parametrize(
-        "ini_file_text, exception_text",
+        "ini_file_text, plugin_version, exception_text",
         [
             pytest.param(
                 """
                 [pytest]
                 required_plugins = a z
                 """,
+                "1.5",
                 "Missing required plugins: a, z",
                 id="2-missing",
             ),
@@ -324,6 +325,7 @@ class TestParseIni:
                 [pytest]
                 required_plugins = a z myplugin
                 """,
+                "1.5",
                 "Missing required plugins: a, z",
                 id="2-missing-1-ok",
             ),
@@ -332,6 +334,7 @@ class TestParseIni:
                 [pytest]
                 required_plugins = myplugin
                 """,
+                "1.5",
                 None,
                 id="1-ok",
             ),
@@ -340,6 +343,7 @@ class TestParseIni:
                 [pytest]
                 required_plugins = myplugin==1.5
                 """,
+                "1.5",
                 None,
                 id="1-ok-pin-exact",
             ),
@@ -348,23 +352,35 @@ class TestParseIni:
                 [pytest]
                 required_plugins = myplugin>1.0,<2.0
                 """,
+                "1.5",
                 None,
                 id="1-ok-pin-loose",
             ),
             pytest.param(
                 """
                 [pytest]
-                required_plugins = pyplugin==1.6
+                required_plugins = myplugin
                 """,
-                "Missing required plugins: pyplugin==1.6",
+                "1.5a1",
+                None,
+                id="1-ok-prerelease",
+            ),
+            pytest.param(
+                """
+                [pytest]
+                required_plugins = myplugin==1.6
+                """,
+                "1.5",
+                "Missing required plugins: myplugin==1.6",
                 id="missing-version",
             ),
             pytest.param(
                 """
                 [pytest]
-                required_plugins = pyplugin==1.6 other==1.0
+                required_plugins = myplugin==1.6 other==1.0
                 """,
-                "Missing required plugins: other==1.0, pyplugin==1.6",
+                "1.5",
+                "Missing required plugins: myplugin==1.6, other==1.0",
                 id="missing-versions",
             ),
             pytest.param(
@@ -373,6 +389,7 @@ class TestParseIni:
                 required_plugins = wont be triggered
                 [pytest]
                 """,
+                "1.5",
                 None,
                 id="invalid-header",
             ),
@@ -383,6 +400,7 @@ class TestParseIni:
         pytester: Pytester,
         monkeypatch: MonkeyPatch,
         ini_file_text: str,
+        plugin_version: str,
         exception_text: str,
     ) -> None:
         """Check 'required_plugins' option with various settings.
@@ -408,7 +426,7 @@ class TestParseIni:
         class DummyDist:
             entry_points = attr.ib()
             files = ()
-            version = "1.5"
+            version = plugin_version
 
             @property
             def metadata(self):