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Carreau merged 2 commits into from
Jul 16, 2026
Merged

Require mypy>=1.20 and fix reveal_type assertions #949

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0bcbf43
Require mypy>=1.20 and fix reveal_type assertions
Carreau Jul 16, 2026
c4e3766
Skip mypy typing tests and mypy install on PyPy
claude Jul 16, 2026
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18 changes: 13 additions & 5 deletions pyproject.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -34,13 +34,13 @@ test = [
"argcomplete>=3.0.3; python_version < '3.12'",
"argcomplete>=3.5.2; python_version >= '3.12'",
# See https://github.com/python/mypy/issues/20329 for PyPy support issue.
# Also, test assertions will need to be updated for 1.20+ because
# `reveal_type()` representations were simplified in
# https://github.com/python/mypy/pull/20929
"mypy>=1.17.0,<1.19",
# `reveal_type()` representations were simplified (dropping the `builtins.`
# prefix) in https://github.com/python/mypy/pull/20929; test assertions in
# tests/test_typing.py target that newer output, so require >=1.20.
"mypy>=1.20; implementation_name != 'pypy'",
"pre-commit",
"pytest-mock",
"pytest-mypy-testing",
"pytest-mypy-testing; implementation_name != 'pypy'",
"pytest>=7.0,<10.0",
]
docs = [
Expand Down Expand Up @@ -98,6 +98,14 @@ show_error_context = true
warn_unreachable = true
exclude = ["examples/docs/configs", "traitlets/tests/test_typing.py"]

[[tool.mypy.overrides]]
# numpy is pulled in transitively via `import pytest` (pytest.approx). Its
# recent stubs use the `type` statement, which mypy rejects under
# python_version = "3.10", aborting the check. Skip following into it.
module = "numpy.*"
follow_imports = "skip"
follow_imports_for_stubs = true

[tool.pytest.ini_options]
minversion = "6.0"
xfail_strict = true
Expand Down
11 changes: 11 additions & 0 deletions tests/conftest.py
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Original file line number Diff line number Diff line change
@@ -0,0 +1,11 @@
from __future__ import annotations

import sys

collect_ignore = []

# mypy does not support PyPy (https://github.com/python/mypy/issues/20329), so
# neither mypy nor pytest-mypy-testing is installed there and the mypy_*_typing
# checks cannot run.
if sys.implementation.name == "pypy":
collect_ignore.append("test_typing.py")
112 changes: 56 additions & 56 deletions tests/test_typing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -59,7 +59,7 @@ def _foo_validate(self, commit: t.Any) -> bool:
return True

t = T()
reveal_type(t.foo) # R: builtins.str
reveal_type(t.foo) # R: str
reveal_type(t._foo_observer) # R: Any
reveal_type(t._foo_validate) # R: Any

Expand Down Expand Up @@ -100,14 +100,14 @@ class T(HasTraits):
).tag(config=True)

t = T()
reveal_type(List(["foo"])) # R: traitlets.traitlets.List[builtins.str]
reveal_type(List([""]).tag(sync=True)) # R: traitlets.traitlets.List[builtins.str]
reveal_type(List(["foo"])) # R: traitlets.traitlets.List[str]
reveal_type(List([""]).tag(sync=True)) # R: traitlets.traitlets.List[str]
reveal_type(List(None, allow_none=True)) # R: traitlets.traitlets.List[Never]
reveal_type(
List(None, allow_none=True).tag(sync=True) # R: traitlets.traitlets.List[Never]
)
reveal_type(T.latex_command) # R: traitlets.traitlets.List[builtins.str]
reveal_type(t.latex_command) # R: builtins.list[builtins.str]
reveal_type(T.latex_command) # R: traitlets.traitlets.List[str]
reveal_type(t.latex_command) # R: list[str]


@pytest.mark.mypy_testing
Expand All @@ -116,12 +116,12 @@ class T(HasTraits):
foo = Dict({}, help="Shell command used to compile latex.").tag(config=True)

t = T()
reveal_type(Dict(None, allow_none=True)) # R: traitlets.traitlets.Dict[builtins.str, Any]
reveal_type(Dict(None, allow_none=True)) # R: traitlets.traitlets.Dict[str, Any]
reveal_type(
Dict(None, allow_none=True).tag(sync=True) # R: traitlets.traitlets.Dict[builtins.str, Any]
Dict(None, allow_none=True).tag(sync=True) # R: traitlets.traitlets.Dict[str, Any]
)
reveal_type(T.foo) # R: traitlets.traitlets.Dict[builtins.str, Any]
reveal_type(t.foo) # R: builtins.dict[builtins.str, Any]
reveal_type(T.foo) # R: traitlets.traitlets.Dict[str, Any]
reveal_type(t.foo) # R: dict[str, Any]


@pytest.mark.mypy_testing
Expand Down Expand Up @@ -162,8 +162,8 @@ class KernelSpecManager(HasTraits):
t = KernelSpecManager()
reveal_type(t.kernel_spec_class) # R: def () -> tests.test_typing.KernelSpec@129
reveal_type(t.kernel_spec_class()) # R: tests.test_typing.KernelSpec@129
reveal_type(t.kernel_spec_class().item) # R: builtins.str
reveal_type(t.other_class) # R: builtins.type
reveal_type(t.kernel_spec_class().item) # R: str
reveal_type(t.other_class) # R: type
reveal_type(t.other_class()) # R: Any
reveal_type(t.other_kernel_spec_class) # R: def () -> tests.test_typing.KernelSpec@129
reveal_type(t.other_kernel_spec_class()) # R: tests.test_typing.KernelSpec@129
Expand All @@ -185,29 +185,29 @@ class T(HasTraits):

t = T()
reveal_type(
Unicode( # R: traitlets.traitlets.Unicode[builtins.str, builtins.str | builtins.bytes]
Unicode( # R: traitlets.traitlets.Unicode[str, str | bytes]
"foo"
)
)
reveal_type(
Unicode( # R: traitlets.traitlets.Unicode[builtins.str, builtins.str | builtins.bytes]
Unicode( # R: traitlets.traitlets.Unicode[str, str | bytes]
""
).tag(sync=True)
)
reveal_type(
Unicode( # R: traitlets.traitlets.Unicode[builtins.str | None, builtins.str | builtins.bytes | None]
Unicode( # R: traitlets.traitlets.Unicode[str | None, str | bytes | None]
None, allow_none=True
)
)
reveal_type(
Unicode( # R: traitlets.traitlets.Unicode[builtins.str | None, builtins.str | builtins.bytes | None]
Unicode( # R: traitlets.traitlets.Unicode[str | None, str | bytes | None]
None, allow_none=True
).tag(sync=True)
)
reveal_type(
T.export_format # R: traitlets.traitlets.Unicode[builtins.str, builtins.str | builtins.bytes]
T.export_format # R: traitlets.traitlets.Unicode[str, str | bytes]
)
reveal_type(t.export_format) # R: builtins.str
reveal_type(t.export_format) # R: str


@pytest.mark.mypy_testing
Expand All @@ -221,12 +221,12 @@ class T(HasTraits):

t = T()
reveal_type(
Enum( # R: traitlets.traitlets.Enum[builtins.str]
Enum( # R: traitlets.traitlets.Enum[str]
("foo",)
)
)
reveal_type(
Enum( # R: traitlets.traitlets.Enum[builtins.str]
Enum( # R: traitlets.traitlets.Enum[str]
[""]
).tag(sync=True)
)
Expand All @@ -241,9 +241,9 @@ class T(HasTraits):
).tag(sync=True)
)
reveal_type(
T.log_level # R: traitlets.traitlets.Enum[builtins.int]
T.log_level # R: traitlets.traitlets.Enum[int]
)
reveal_type(t.log_level) # R: builtins.int
reveal_type(t.log_level) # R: int


@pytest.mark.mypy_testing
Expand Down Expand Up @@ -277,9 +277,9 @@ class T(HasTraits):
reveal_type(Set(None, allow_none=True)) # R: traitlets.traitlets.Set
reveal_type(Set(None, allow_none=True).tag(sync=True)) # R: traitlets.traitlets.Set
reveal_type(T.remove_cell_tags) # R: traitlets.traitlets.Set
reveal_type(t.remove_cell_tags) # R: builtins.set[Any]
reveal_type(t.remove_cell_tags) # R: set[Any]
reveal_type(T.safe_output_keys) # R: traitlets.traitlets.Set
reveal_type(t.safe_output_keys) # R: builtins.set[Any]
reveal_type(t.safe_output_keys) # R: set[Any]


@pytest.mark.mypy_testing
Expand Down Expand Up @@ -312,33 +312,33 @@ class T(HasTraits):

t = T()
reveal_type(
Bool(True) # R: traitlets.traitlets.Bool[builtins.bool, builtins.bool | builtins.int]
Bool(True) # R: traitlets.traitlets.Bool[bool, bool | int]
)
reveal_type(
Bool( # R: traitlets.traitlets.Bool[builtins.bool, builtins.bool | builtins.int]
Bool( # R: traitlets.traitlets.Bool[bool, bool | int]
True
).tag(sync=True)
)
reveal_type(
Bool( # R: traitlets.traitlets.Bool[builtins.bool | None, builtins.bool | builtins.int | None]
Bool( # R: traitlets.traitlets.Bool[bool | None, bool | int | None]
None, allow_none=True
)
)
reveal_type(
Bool( # R: traitlets.traitlets.Bool[builtins.bool | None, builtins.bool | builtins.int | None]
Bool( # R: traitlets.traitlets.Bool[bool | None, bool | int | None]
None, allow_none=True
).tag(sync=True)
)
reveal_type(
T.b # R: traitlets.traitlets.Bool[builtins.bool, builtins.bool | builtins.int]
T.b # R: traitlets.traitlets.Bool[bool, bool | int]
)
reveal_type(t.b) # R: builtins.bool
reveal_type(t.ob) # R: builtins.bool | None
reveal_type(t.b) # R: bool
reveal_type(t.ob) # R: bool | None
reveal_type(
T.b # R: traitlets.traitlets.Bool[builtins.bool, builtins.bool | builtins.int]
T.b # R: traitlets.traitlets.Bool[bool, bool | int]
)
reveal_type(
T.ob # R: traitlets.traitlets.Bool[builtins.bool | None, builtins.bool | builtins.int | None]
T.ob # R: traitlets.traitlets.Bool[bool | None, bool | int | None]
)
# we would expect this to be bool | int | None, but...
t.b = "foo" # E: Incompatible types in assignment (expression has type "str", variable has type "bool | int") [assignment]
Expand All @@ -352,24 +352,24 @@ class T(HasTraits):
oi: Int[int | None, int | None] = Int(42, allow_none=True).tag(sync=True)

t = T()
reveal_type(Int(True)) # R: traitlets.traitlets.Int[builtins.int, builtins.int]
reveal_type(Int(True).tag(sync=True)) # R: traitlets.traitlets.Int[builtins.int, builtins.int]
reveal_type(Int(True)) # R: traitlets.traitlets.Int[int, int]
reveal_type(Int(True).tag(sync=True)) # R: traitlets.traitlets.Int[int, int]
reveal_type(
Int( # R: traitlets.traitlets.Int[builtins.int | None, builtins.int | None]
Int( # R: traitlets.traitlets.Int[int | None, int | None]
None, allow_none=True
)
)
reveal_type(
Int( # R: traitlets.traitlets.Int[builtins.int | None, builtins.int | None]
Int( # R: traitlets.traitlets.Int[int | None, int | None]
None, allow_none=True
).tag(sync=True)
)
reveal_type(T.i) # R: traitlets.traitlets.Int[builtins.int, builtins.int]
reveal_type(t.i) # R: builtins.int
reveal_type(t.oi) # R: builtins.int | None
reveal_type(T.i) # R: traitlets.traitlets.Int[builtins.int, builtins.int]
reveal_type(T.i) # R: traitlets.traitlets.Int[int, int]
reveal_type(t.i) # R: int
reveal_type(t.oi) # R: int | None
reveal_type(T.i) # R: traitlets.traitlets.Int[int, int]
reveal_type(
T.oi # R: traitlets.traitlets.Int[builtins.int | None, builtins.int | None]
T.oi # R: traitlets.traitlets.Int[int | None, int | None]
)
t.i = "foo" # E: Incompatible types in assignment (expression has type "str", variable has type "int") [assignment]
t.i = None # E: Incompatible types in assignment (expression has type "None", variable has type "int") [assignment]
Expand All @@ -383,21 +383,21 @@ class T(HasTraits):
oi = CInt(42, allow_none=True).tag(sync=True)

t = T()
reveal_type(CInt(42)) # R: traitlets.traitlets.CInt[builtins.int, Any]
reveal_type(CInt(42).tag(sync=True)) # R: traitlets.traitlets.CInt[builtins.int, Any]
reveal_type(CInt(42)) # R: traitlets.traitlets.CInt[int, Any]
reveal_type(CInt(42).tag(sync=True)) # R: traitlets.traitlets.CInt[int, Any]
reveal_type(
CInt(None, allow_none=True) # R: traitlets.traitlets.CInt[builtins.int | None, Any]
CInt(None, allow_none=True) # R: traitlets.traitlets.CInt[int | None, Any]
)
reveal_type(
CInt( # R: traitlets.traitlets.CInt[builtins.int | None, Any]
CInt( # R: traitlets.traitlets.CInt[int | None, Any]
None, allow_none=True
).tag(sync=True)
)
reveal_type(T.i) # R: traitlets.traitlets.CInt[builtins.int, Any]
reveal_type(t.i) # R: builtins.int
reveal_type(t.oi) # R: builtins.int | None
reveal_type(T.i) # R: traitlets.traitlets.CInt[builtins.int, Any]
reveal_type(T.oi) # R: traitlets.traitlets.CInt[builtins.int | None, Any]
reveal_type(T.i) # R: traitlets.traitlets.CInt[int, Any]
reveal_type(t.i) # R: int
reveal_type(t.oi) # R: int | None
reveal_type(T.i) # R: traitlets.traitlets.CInt[int, Any]
reveal_type(T.oi) # R: traitlets.traitlets.CInt[int | None, Any]


@pytest.mark.mypy_testing
Expand All @@ -407,21 +407,21 @@ class T(HasTraits):
otcp = TCPAddress(None, allow_none=True)

t = T()
reveal_type(t.tcp) # R: tuple[builtins.str, builtins.int]
reveal_type(t.tcp) # R: tuple[str, int]
reveal_type(
T.tcp # R: traitlets.traitlets.TCPAddress[tuple[builtins.str, builtins.int], tuple[builtins.str, builtins.int]]
T.tcp # R: traitlets.traitlets.TCPAddress[tuple[str, int], tuple[str, int]]
)
reveal_type(
T.tcp.tag( # R:traitlets.traitlets.TCPAddress[tuple[builtins.str, builtins.int], tuple[builtins.str, builtins.int]]
T.tcp.tag( # R:traitlets.traitlets.TCPAddress[tuple[str, int], tuple[str, int]]
sync=True
)
)
reveal_type(t.otcp) # R: tuple[builtins.str, builtins.int] | None
reveal_type(t.otcp) # R: tuple[str, int] | None
reveal_type(
T.otcp # R: traitlets.traitlets.TCPAddress[tuple[builtins.str, builtins.int] | None, tuple[builtins.str, builtins.int] | None]
T.otcp # R: traitlets.traitlets.TCPAddress[tuple[str, int] | None, tuple[str, int] | None]
)
reveal_type(
T.otcp.tag( # R: traitlets.traitlets.TCPAddress[tuple[builtins.str, builtins.int] | None, tuple[builtins.str, builtins.int] | None]
T.otcp.tag( # R: traitlets.traitlets.TCPAddress[tuple[str, int] | None, tuple[str, int] | None]
sync=True
)
)
Expand Down
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