Minimal mypy setup

.github/workflows/main.yaml

@@ -68,6 +68,22 @@ jobs:
       - uses: actions/setup-python@main
       - uses: pre-commit/action@main
 
+  typecheck:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+
+      - name: Setup conda
+        uses: mamba-org/provision-with-micromamba@main
+        with:
+          environment-file: ci/environment-typecheck.yml
+
+      - name: mypy
+        shell: bash -l {0}
+        run: |
+          mypy fsspec
+
   downstream:
     name: downstream
     runs-on: ubuntu-latest

ci/environment-typecheck.yml

@@ -0,0 +1,13 @@
+name: test_env
+channels:
+  - conda-forge
+dependencies:
+  - mypy=1.3
+  - pyarrow
+  - python=3.8
+  - pip
+  - pip:
+    - types-paramiko
+    - types-requests
+    - types-tqdm
+    - types-ujson

setup.cfg

@@ -37,3 +37,18 @@ skip=
     docs/source/conf.py
     versioneer.py
     fsspec/_version
+
+[mypy]
+follow_imports = normal
+ignore_missing_imports = True
+enable_error_code = ignore-without-code,truthy-bool,truthy-iterable,unused-awaitable
+
+disallow_untyped_decorators = True
+strict_equality = True
+warn_redundant_casts = True
+warn_unused_configs = True
+warn_unused_ignores = True
+
+
+# don't bother type-checking test_*.py or conftest.py files
+exclude = (test_.*|conftest)\.py$