enforce mypy and fix errors

langchain/formatting.py

@@ -1,17 +1,25 @@
 """Utilities for formatting strings."""
 from string import Formatter
+from typing import Any, Mapping, Sequence, Union
 
 
 class StrictFormatter(Formatter):
     """A subclass of formatter that checks for extra keys."""
 
-    def check_unused_args(self, used_args, args, kwargs):
+    def check_unused_args(
+        self,
+        used_args: Sequence[Union[int, str]],
+        args: Sequence,
+        kwargs: Mapping[str, Any],
+    ) -> None:
         """Check to see if extra parameters are passed."""
         extra = set(kwargs).difference(used_args)
         if extra:
             raise KeyError(extra)
 
-    def vformat(self, format_string, args, kwargs):
+    def vformat(
+        self, format_string: str, args: Sequence, kwargs: Mapping[str, Any]
+    ) -> str:
         """Check that no arguments are provided."""
         if len(args) > 0:
             raise ValueError(

pyproject.toml

@@ -3,4 +3,5 @@ profile = "black"
 
 [tool.mypy]
 ignore_missing_imports = "True"
+disallow_untyped_defs = "True"
 exclude = ["notebooks"]

tests/unit_tests/test_formatting.py

@@ -4,22 +4,22 @@
 from langchain.formatting import formatter
 
 
-def test_valid_formatting():
+def test_valid_formatting() -> None:
     """Test formatting works as expected."""
     template = "This is a {foo} test."
     output = formatter.format(template, foo="good")
     expected_output = "This is a good test."
     assert output == expected_output
 
 
-def test_does_not_allow_args():
+def test_does_not_allow_args() -> None:
     """Test formatting raises error when args are provided."""
     template = "This is a {} test."
     with pytest.raises(ValueError):
         formatter.format(template, "good")
 
 
-def test_does_not_allow_extra_kwargs():
+def test_does_not_allow_extra_kwargs() -> None:
     """Test formatting does not allow extra key word arguments."""
     template = "This is a {foo} test."
     with pytest.raises(KeyError):

tests/unit_tests/test_prompt.py

@@ -4,7 +4,7 @@
 from langchain.prompt import Prompt
 
 
-def test_prompt_valid():
+def test_prompt_valid() -> None:
     """Test prompts can be constructed."""
     template = "This is a {foo} test."
     input_variables = ["foo"]
@@ -13,23 +13,23 @@ def test_prompt_valid():
     assert prompt.input_variables == input_variables
 
 
-def test_prompt_missing_input_variables():
+def test_prompt_missing_input_variables() -> None:
     """Test error is raised when input variables are not provided."""
     template = "This is a {foo} test."
-    input_variables = []
+    input_variables: list = []
     with pytest.raises(ValueError):
         Prompt(input_variables=input_variables, template=template)
 
 
-def test_prompt_extra_input_variables():
+def test_prompt_extra_input_variables() -> None:
     """Test error is raised when there are too many input variables."""
     template = "This is a {foo} test."
     input_variables = ["foo", "bar"]
     with pytest.raises(ValueError):
         Prompt(input_variables=input_variables, template=template)
 
 
-def test_prompt_wrong_input_variables():
+def test_prompt_wrong_input_variables() -> None:
     """Test error is raised when name of input variable is wrong."""
     template = "This is a {foo} test."
     input_variables = ["bar"]