Add test cases for virtual package priorities (#238)

These test cases were intended for
astral-sh/uv#10935. They still test the virtual
package priorities, even though they are not observable in the
resolution outcome in the current resolver usage. They can be used to
observe virtual package prioritization in resolver verbose mode, so I'd
keep them in case we have to follow-up to
astral-sh/uv#10935

Author: konstin

scenarios/tag_and_markers/virtual-package-extra-priorities.toml

@@ -0,0 +1,26 @@
+name = "marker-variants-have-different-extras"
+description = "Check the prioritization for virtual extra and marker packages"
+
+[expected]
+satisfiable = true
+
+[environment]
+python = "3.12"
+
+[root]
+requires = [
+  "psycopg[binary] ; platform_python_implementation != 'PyPy'",
+  "psycopg ; platform_python_implementation == 'PyPy'",
+]
+
+[packages.psycopg.versions."1.0.0"]
+requires = ['tzdata; sys_platform == "win32"']
+
+[packages.psycopg.versions."1.0.0".extras]
+binary = ["psycopg-binary; implementation_name != 'pypy'"]
+
+[packages.psycopg-binary.versions."1.0.0"]
+[packages.tzdata.versions."1.0.0"]
+
+[resolver_options]
+universal = true

scenarios/tag_and_markers/virtual-package-marker-priorities.toml

@@ -0,0 +1,23 @@
+name = "virtual-package-extra-priorities"
+description = "Check the prioritization for virtual marker packages"
+
+[root]
+requires_python = ">=3.12"
+requires = ["a==1; python_version >= '3.8'", "b; python_version >= '3.9'"]
+
+[expected]
+satisfiable = true
+
+[packages.a.versions."1.0.0"]
+requires = ["b==1 ; python_version >= '3.10'"]
+[packages.a.versions."2.0.0"]
+requires = ["b==1 ; python_version >= '3.10'"]
+
+[packages.b.versions."1.0.0"]
+[packages.b.versions."2.0.0"]
+
+[resolver_options]
+universal = true
+
+[environment]
+python = "3.12"