[PEP 695] Add daemon tests that use new type parameter syntax (#17327)

Add some basic mypy daemon test coverage, and make it possible to write
daemon tests that only work on recent Python versions.

Everything tested seems to work already.

Work on #15238.

mypy/test/testdeps.py

@@ -3,8 +3,11 @@
 from __future__ import annotations
 
 import os
+import sys
 from collections import defaultdict
 
+import pytest
+
 from mypy import build
 from mypy.errors import CompileError
 from mypy.modulefinder import BuildSource
@@ -28,6 +31,8 @@ def run_case(self, testcase: DataDrivenTestCase) -> None:
         src = "\n".join(testcase.input)
         dump_all = "# __dump_all__" in src
         options = parse_options(src, testcase, incremental_step=1)
+        if options.python_version > sys.version_info:
+            pytest.skip("Test case requires a newer Python version")
         options.use_builtins_fixtures = True
         options.show_traceback = True
         options.cache_dir = os.devnull

mypy/test/testdiff.py

@@ -3,9 +3,11 @@
 from __future__ import annotations
 
 import os
+import sys
+
+import pytest
 
 from mypy import build
-from mypy.defaults import PYTHON3_VERSION
 from mypy.errors import CompileError
 from mypy.modulefinder import BuildSource
 from mypy.nodes import MypyFile
@@ -24,6 +26,8 @@ def run_case(self, testcase: DataDrivenTestCase) -> None:
         files_dict = dict(testcase.files)
         second_src = files_dict["tmp/next.py"]
         options = parse_options(first_src, testcase, 1)
+        if options.python_version > sys.version_info:
+            pytest.skip("Test case requires a newer Python version")
 
         messages1, files1 = self.build(first_src, options)
         messages2, files2 = self.build(second_src, options)
@@ -53,7 +57,6 @@ def build(self, source: str, options: Options) -> tuple[list[str], dict[str, Myp
         options.use_builtins_fixtures = True
         options.show_traceback = True
         options.cache_dir = os.devnull
-        options.python_version = PYTHON3_VERSION
         options.allow_empty_bodies = True
         try:
             result = build.build(

mypy/test/testfinegrained.py

@@ -16,6 +16,7 @@
 
 import os
 import re
+import sys
 import unittest
 from typing import Any
 
@@ -82,6 +83,9 @@ def run_case(self, testcase: DataDrivenTestCase) -> None:
             f.write(main_src)
 
         options = self.get_options(main_src, testcase, build_cache=False)
+        if options.python_version > sys.version_info:
+            pytest.skip("Test case requires a newer Python version")
+
         build_options = self.get_options(main_src, testcase, build_cache=True)
         server = Server(options, DEFAULT_STATUS_FILE)
 

mypy/traverser.py

@@ -246,7 +246,6 @@ def visit_match_stmt(self, o: MatchStmt) -> None:
 
     def visit_type_alias_stmt(self, o: TypeAliasStmt) -> None:
         o.name.accept(self)
-        # TODO: params
         o.value.accept(self)
 
     def visit_member_expr(self, o: MemberExpr) -> None:

test-data/unit/deps.test

@@ -1431,3 +1431,19 @@ class B(A):
 <m.Z> -> m
 <dataclasses.dataclass> -> m
 <dataclasses> -> m
+
+[case testPEP695TypeAliasDeps]
+# flags: --enable-incomplete-feature=NewGenericSyntax --python-version=3.12
+from a import C, E
+type A = C
+type A2 = A
+type A3 = E
+[file a.py]
+class C: pass
+class D: pass
+type E = D
+[out]
+<m.A> -> m
+<a.C> -> m
+<a.E> -> m
+<a> -> m

test-data/unit/diff.test

@@ -1530,3 +1530,102 @@ class C:
 [out]
 __main__.C.get_by_team_and_id
 __main__.Optional
+
+[case testPEP695TypeAlias]
+# flags: --enable-incomplete-feature=NewGenericSyntax --python-version=3.12
+from typing_extensions import TypeAlias, TypeAliasType
+type A = int
+type B = str
+type C = int
+D = int
+E: TypeAlias = int
+F = TypeAliasType("F", int)
+G = TypeAliasType("G", int)
+type H = int
+
+[file next.py]
+# flags: --enable-incomplete-feature=NewGenericSyntax --python-version=3.12
+from typing_extensions import TypeAlias, TypeAliasType
+type A = str
+type B = str
+type C[T] = int
+type D = int
+type E = int
+type F = int
+type G = str
+type H[T] = int
+
+[builtins fixtures/tuple.pyi]
+[typing fixtures/typing-full.pyi]
+[out]
+__main__.A
+__main__.C
+__main__.D
+__main__.E
+__main__.G
+__main__.H
+
+[case testPEP695TypeAlias2]
+# flags: --enable-incomplete-feature=NewGenericSyntax --python-version=3.12
+type A[T: int] = list[T]
+type B[T: int] = list[T]
+type C[T: (int, str)] = list[T]
+type D[T: (int, str)] = list[T]
+type E[T: int] = list[T]
+type F[T: (int, str)] = list[T]
+
+[file next.py]
+# flags: --enable-incomplete-feature=NewGenericSyntax --python-version=3.12
+type A[T] = list[T]
+type B[T: str] = list[T]
+type C[T: (int, None)] = list[T]
+type D[T] = list[T]
+type E[T: int] = list[T]
+type F[T: (int, str)] = list[T]
+
+[out]
+__main__.A
+__main__.B
+__main__.C
+__main__.D
+
+[case testPEP695GenericFunction]
+# flags: --enable-incomplete-feature=NewGenericSyntax --python-version=3.12
+def f[T](x: T) -> T:
+    return x
+def g[T](x: T, y: T) -> T:
+    return x
+[file next.py]
+# flags: --enable-incomplete-feature=NewGenericSyntax --python-version=3.12
+def f[T](x: T) -> T:
+    return x
+def g[T, S](x: T, y: S) -> S:
+    return y
+[out]
+__main__.g
+
+[case testPEP695GenericClass]
+# flags: --enable-incomplete-feature=NewGenericSyntax --python-version=3.12
+class C[T]:
+    pass
+class D[T]:
+    pass
+class E[T]:
+    pass
+class F[T]:
+    def f(self, x: object) -> T: ...
+[file next.py]
+# flags: --enable-incomplete-feature=NewGenericSyntax --python-version=3.12
+class C[T]:
+    pass
+class D[T: int]:
+    pass
+class E:
+    pass
+class F[T]:
+    def f(self, x: T) -> T: ...
+[out]
+__main__.D
+__main__.E
+__main__.F
+__main__.F.f

test-data/unit/fine-grained-python312.test

@@ -0,0 +1,81 @@
+[case testPEP695TypeAliasDep]
+# flags: --enable-incomplete-feature=NewGenericSyntax
+import m
+def g() -> m.C:
+    return m.f()
+[file m.py]
+type C = int
+
+def f() -> int:
+    pass
+[file m.py.2]
+type C = str
+
+def f() -> int:
+    pass
+[out]
+==
+main:4: error: Incompatible return value type (got "int", expected "str")
+
+[case testPEP695ChangeOldStyleToNewStyleTypeAlias]
+# flags: --enable-incomplete-feature=NewGenericSyntax
+from m import A
+A()
+
+[file m.py]
+A = int
+
+[file m.py.2]
+type A = int
+[typing fixtures/typing-full.pyi]
+[builtins fixtures/tuple.pyi]
+[out]
+==
+main:3: error: "TypeAliasType" not callable
+
+[case testPEP695VarianceChangesDueToDependency]
+# flags: --enable-incomplete-feature=NewGenericSyntax
+from a import C
+
+x: C[object] = C[int]()
+
+[file a.py]
+from b import A
+
+class C[T]:
+    def f(self) -> A[T]: ...
+
+[file b.py]
+class A[T]:
+    def f(self) -> T: ...
+
+[file b.py.2]
+class A[T]:
+    def f(self) -> list[T]: ...
+
+[out]
+==
+main:4: error: Incompatible types in assignment (expression has type "C[int]", variable has type "C[object]")
+
+[case testPEP695TypeAliasChangesDueToDependency]
+# flags: --enable-incomplete-feature=NewGenericSyntax
+from a import A
+x: A
+x = 0
+x = ''
+
+[file a.py]
+from b import B
+type A = B[int, str]
+
+[file b.py]
+from typing import Union as B
+
+[file b.py.2]
+from builtins import tuple as B
+
+[builtins fixtures/tuple.pyi]
+[out]
+==
+main:4: error: Incompatible types in assignment (expression has type "int", variable has type "tuple[int, str]")
+main:5: error: Incompatible types in assignment (expression has type "str", variable has type "tuple[int, str]")