Stricter ruff/ty checking

CHANGELOG.md

@@ -11,6 +11,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Releases from v0.4.0 onwards are now archived with a DOI. A badge at the top of the README shows the DOI of the last release. ([@brews](https://github.com/brews), [PR#94](https://github.com/ClimateImpactLab/isku/pull/94))
 
+### Changed
+
+- Stricter type checking from ruff/ty. ([@brews](https://github.com/brews), [PR#125](https://github.com/ClimateImpactLab/isku/pull/125))
+
 ## [0.4.0] - 2026-07-24
 
 ### Added

prek.toml

@@ -14,7 +14,7 @@ hooks = [
 
 [[repos]]
 repo = "https://github.com/astral-sh/ruff-pre-commit"
-rev = "v0.15.12"
+rev = "v0.16.6"
 hooks = [
   { id = "ruff-check", args = ["--fix", "--show-fixes"] },
   { id = "ruff-format" },

pyproject.toml

@@ -14,7 +14,7 @@ tests = [
   "numpy>=2.4.4",
   "pytest>=9.0.3",
   "pytest-cov>=7.1.0",
-  "ruff>=0.15.12",
+  "ruff>=0.16.0",
   "ty>=0.0.35",
 ]
 docs = ["mkdocstrings[python]>=1.0.4", "zensical>=0.0.41"]
@@ -30,6 +30,7 @@ build-backend = "uv_build"
 
 [tool.ruff.lint]
 extend-select = [
+  "ANN",
   "YTT",  # flake8-2020
   "B",    # flake8-bugbear
   "C4",   # flake8-comprehensions
@@ -51,10 +52,17 @@ extend-select = [
   "FURB", # refurb
   "RUF",
 ]
+preview = true
 
 [tool.ruff.lint.isort]
 known-first-party = ["isku"]
 
 [tool.ruff.lint.flake8-tidy-imports]
 # Disallow all relative imports.
 ban-relative-imports = "all"
+
+[tool.ty.rules]
+dynamic-function-decorator-return = "error"
+missing-type-argument = "error"
+possibly-unresolved-reference = "warn"
+unsound-return-statement = "error"

src/isku/extract.py

@@ -106,7 +106,7 @@ class GridWeightingRegions(RegionExtractor):
     RegionExtractor: Protocol for regionalizing, or extracting regions from a dataset.
     """
 
-    def __init__(self, weights: xr.Dataset):
+    def __init__(self, weights: xr.Dataset) -> None:
         target_variables = ("lat", "lon", "weight", "region")
         missing_variables = [v for v in target_variables if v not in weights.variables]
         if missing_variables:

tests/smoke_test.py

@@ -7,24 +7,24 @@
 import isku
 
 
-def test_basic_projection():
+def test_basic_projection() -> None:
     """
     Basic test running build_projection_template() with project().
     """
     predictors = xr.Dataset({"foobar": (["idx"], [0, 0, 0])})
     params = xr.Dataset({"ni": (["idx"], [1, 2, 3])})
     expected = xr.Dataset({"impact": (["idx"], [13, 14, 15])})
 
-    def _pre(x):
+    def _pre(x: xr.Dataset) -> xr.Dataset:
         out = xr.Dataset()
         out["foobar"] = x["foobar"] + 1
         out["ni"] = x["ni"]
         return out
 
-    def _post(x):
+    def _post(x: xr.Dataset) -> xr.Dataset:
         return x[["impact"]] + 10
 
-    def _model(x):
+    def _model(x: xr.Dataset) -> xr.Dataset:
         return (x["foobar"] * 2 + x["ni"]).to_dataset(name="impact")
 
     test_impact_model = isku.build_projection_template(

tests/test_extraction.py

@@ -8,7 +8,7 @@
 import isku
 
 
-def test_extract_regions():
+def test_extract_regions() -> None:
     """
     Create simple extraction template and test basic region extraction.
     """
@@ -17,10 +17,10 @@ def test_extract_regions():
 
     # Each of the transformation steps should add to the variable.
     # We'll know something basic is off if it doesn't add to `expected`.
-    def _pre(x):
+    def _pre(x: xr.Dataset) -> xr.Dataset:
         return x[["variable1"]] + 1
 
-    def _post(x):
+    def _post(x: xr.Dataset) -> xr.Dataset:
         return x[["variable1"]] + 10
 
     test_transform = isku.build_extraction_template(pre=_pre, post=_post)
@@ -30,7 +30,7 @@ class FakeRegionalization(isku.RegionExtractor):
         Toy implementation of the RegionExtractor protocol
         """
 
-        def extract_regions(self, ds):
+        def extract_regions(self, ds: xr.Dataset) -> xr.Dataset:  # ruff: ignore[no-self-use]
             return ds[["variable1"]] + 2.5
 
     output = isku.extract_regions(
@@ -42,7 +42,7 @@ def extract_regions(self, ds):
     xr.testing.assert_allclose(output, expected)
 
 
-def test_gridweightingregions_region_extraction():
+def test_gridweightingregions_region_extraction() -> None:
     """
     Basic test calling GridWeightingRegions for regionalization with the RegionExtractor protocol.
     """
@@ -81,7 +81,7 @@ def test_gridweightingregions_region_extraction():
     xr.testing.assert_allclose(actual, expected)
 
 
-def test_gridweightingregions_extract_regions_with_extradim():
+def test_gridweightingregions_extract_regions_with_extradim() -> None:
     """
     Basic GridWeightingRegions regionalization test, but if input data has extra time dim.
     """

tests/test_projection.py

@@ -7,24 +7,24 @@
 from isku import build_projection_template, project
 
 
-def test_basic_projection():
+def test_basic_projection() -> None:
     """
     Basic test running build_projection_template() with project().
     """
     predictors = xr.Dataset({"foobar": (["idx"], [0, 0, 0])})
     params = xr.Dataset({"ni": (["idx"], [1, 2, 3])})
     expected = xr.Dataset({"impact": (["idx"], [13, 14, 15])})
 
-    def _pre(x):
+    def _pre(x: xr.Dataset) -> xr.Dataset:
         out = xr.Dataset()
         out["foobar"] = x["foobar"] + 1
         out["ni"] = x["ni"]
         return out
 
-    def _post(x):
+    def _post(x: xr.Dataset) -> xr.Dataset:
         return x[["impact"]] + 10
 
-    def _model(x):
+    def _model(x: xr.Dataset) -> xr.Dataset:
         return (x["foobar"] * 2 + x["ni"]).to_dataset(name="impact")
 
     test_impact_model = build_projection_template(