test: Retire type checker "if KEYWORD:" usage

Such pattern is not supported by pyrefly and ty, thus replaced by injector pytest marks.

Author: abelcheung

pyproject.toml

@@ -49,7 +49,7 @@ dev = [
     'urllib3 >= 2.0',
     "pytest >= 7.0, < 9",
     'pytest-mypy-plugins >= 3.2.0',
-    'pytest-revealtype-injector >= 0.7.1',
+    'pytest-revealtype-injector >= 0.8.0',
     'lxml >= 5.0',
     'rnc2rng',
     'hypothesis >= 6.127.7',  # HypothesisWorks/hypothesis#4269
@@ -89,7 +89,7 @@ rt-test = [
     "hypothesis == 6.148.8",
     "tzdata",
     "pytest >= 7.0, < 9",
-    "pytest-revealtype-injector == 0.7.1",
+    "pytest-revealtype-injector == 0.8.0",
     "rnc2rng == 2.7.0",
     {include-group = "mypy"},
     {include-group = "pyright"},

tests/runtime/elem/test_basic.py

@@ -38,9 +38,6 @@
 else:
     from typing_extensions import reveal_type
 
-# See mypy.ini in testsuite for explanation
-TC_HONORS_REVERSED = True
-
 
 class TestBasicBehavior:
     def test_sequence_read(self, xml2_root: _Element) -> None:
@@ -58,16 +55,6 @@ def test_sequence_read(self, xml2_root: _Element) -> None:
         assert elem.index(item) == 0
         del itr, item
 
-        if TC_HONORS_REVERSED:
-            rev = reversed(elem)
-        else:
-            rev = elem.__reversed__()
-        reveal_type(rev)
-        item = next(rev)
-        reveal_type(item)
-        assert elem.index(item) == length - 1
-        del rev, item
-
         for sub in elem:
             reveal_type(sub)
 
@@ -81,6 +68,20 @@ def test_sequence_read(self, xml2_root: _Element) -> None:
 
         del elem, subelem
 
+    # mypy and ty don't support magic method and always treat
+    # reversed(...) as `reversed` object
+    @pytest.mark.notypechecker("mypy", "ty")
+    def test_reversed_seq_read_1(self, xml2_root: _Element) -> None:
+        rev = reversed(xml2_root)
+        reveal_type(rev)
+        reveal_type(list(rev))
+
+    @pytest.mark.onlytypechecker("mypy", "ty")
+    def test_reversed_seq_read_2(self, xml2_root: _Element) -> None:
+        rev = xml2_root.__reversed__()
+        reveal_type(rev)
+        reveal_type(list(rev))
+
     def test_sequence_modify(self, xml2_root: _Element) -> None:
         elem = deepcopy(xml2_root)
 

tests/runtime/mypy.ini

@@ -20,15 +20,3 @@ ignore_missing_imports = True
 # statements frequently used in tests.
 
 disable_error_code = func-returns-value
-
-# In some other cases, tests have to be altered in
-# alternative form for mypy to be functional.
-#
-# -- TC_HONORS_REVERSED
-# Mypy thinks reversed(T) always produce reversed object,
-# ignoring annotation completely.
-# Mypy groks T.__reversed__() however, just not honoring
-# the fact that reversed(T) is T.__reversed__() if
-# available.
-
-always_false = TC_HONORS_REVERSED