Use __future__.annotations instead of stringified type annotations

`from __future__ import annotations` became available in Python 3.7, so
there is no reason for us not to use it instead of the older
"stringified" type annotations (for types that are not yet declared at
the time the parser encounters the annotation).

fawltydeps/main.py

@@ -10,6 +10,8 @@
 arguments.
 """
 
+from __future__ import annotations
+
 import json
 import logging
 import sys
@@ -168,7 +170,7 @@ def unused_deps(self) -> List[UnusedDependency]:
         )
 
     @classmethod
-    def create(cls, settings: Settings, stdin: Optional[BinaryIO] = None) -> "Analysis":
+    def create(cls, settings: Settings, stdin: Optional[BinaryIO] = None) -> Analysis:
         """Exercise FawltyDeps' core logic according to the given settings.
 
         Perform the actions specified in 'settings.actions' and apply the other

fawltydeps/settings.py

@@ -1,4 +1,6 @@
 """FawltyDeps configuration and command-line options."""
+from __future__ import annotations
+
 import argparse
 import json
 import logging
@@ -61,7 +63,7 @@ class OrderedEnum(Enum):
     def __lt__(self, other: object) -> bool:
         if not isinstance(other, OrderedEnum):
             return NotImplemented
-        values: List["OrderedEnum"] = list(self.__class__)
+        values: List[OrderedEnum] = list(self.__class__)
         return values.index(self) < values.index(other)
 
 
@@ -205,7 +207,7 @@ def customise_sources(
             )
 
     @classmethod
-    def config(cls, **kwargs: Union[None, Path, str]) -> Type["Settings"]:
+    def config(cls, **kwargs: Union[None, Path, str]) -> Type[Settings]:
         """Configure the class variables in this Settings class.
 
         This must be done _before_ instantiating Settings objects, as the
@@ -218,7 +220,7 @@ class variables affect how this instantiation is done (e.g. which
         return cls
 
     @classmethod
-    def create(cls, cmdline_args: argparse.Namespace) -> "Settings":
+    def create(cls, cmdline_args: argparse.Namespace) -> Settings:
         """Convert the parsed command-line args into a Settings object.
 
         Extract the relevant parts of the given argparse.Namespace object into

fawltydeps/types.py

@@ -1,5 +1,7 @@
 """Common types used across FawltyDeps."""
 
+from __future__ import annotations
+
 import sys
 from abc import ABC, abstractmethod
 from dataclasses import asdict, dataclass, field, replace
@@ -54,7 +56,7 @@ class Source(ABC):
     This exists to inject the class name of the subclass into our JSON output.
     """
 
-    source_type: Type["Source"] = field(init=False)
+    source_type: Type[Source] = field(init=False)
 
     def __post_init__(self) -> None:
         object.__setattr__(self, "source_type", self.__class__)
@@ -248,7 +250,7 @@ def __str__(self) -> str:
             ret += f":{self.lineno}"
         return ret
 
-    def supply(self, **changes: int) -> "Location":
+    def supply(self, **changes: int) -> Location:
         """Create a new Location that contains additional information."""
         return replace(self, **changes)
 

tests/project_helpers.py

@@ -1,4 +1,6 @@
 """Common helpers shared between test_real_project and test_sample_projects."""
+from __future__ import annotations
+
 import hashlib
 import logging
 import os
@@ -48,7 +50,7 @@ class TarballPackage:
     filename_must_include: Optional[str] = None
 
     @classmethod
-    def collect_from_toml(cls, path: Path) -> Iterator["TarballPackage"]:
+    def collect_from_toml(cls, path: Path) -> Iterator[TarballPackage]:
         """Parse information on all available tarball packages in a toml file."""
         tarballs = parse_toml(path)
         for info in tarballs.values():
@@ -226,7 +228,7 @@ class AnalysisExpectations:
     unused_deps: Optional[Set[str]] = None
 
     @classmethod
-    def from_toml(cls, data: TomlData) -> "AnalysisExpectations":
+    def from_toml(cls, data: TomlData) -> AnalysisExpectations:
         """Read expectations from the given TOML table."""
 
         def set_or_none(data: Optional[Iterable[str]]) -> Optional[Set[str]]:
@@ -292,7 +294,7 @@ def _init_args_from_toml(name: str, data: TomlData) -> Dict[str, Any]:
 
     @classmethod
     @abstractmethod
-    def from_toml(cls, name: str, data: TomlData) -> "BaseExperiment":
+    def from_toml(cls, name: str, data: TomlData) -> BaseExperiment:
         """Create an instance from TOML data."""
         raise NotImplementedError
 
@@ -336,7 +338,7 @@ def _init_args_from_toml(
 
     @classmethod
     @abstractmethod
-    def collect(cls) -> Iterator["BaseProject"]:
+    def collect(cls) -> Iterator[BaseProject]:
         """Find and generate all projects in this test suite."""
         raise NotImplementedError
 

tests/test_real_projects.py

@@ -5,6 +5,8 @@
 FawltyDeps on them, with hardcoded expectations per project on what FawltyDeps
 should find/report.
 """
+from __future__ import annotations
+
 import json
 import logging
 import subprocess
@@ -77,7 +79,7 @@ class Experiment(BaseExperiment):
     args: List[str]
 
     @classmethod
-    def from_toml(cls, name: str, data: TomlData) -> "Experiment":
+    def from_toml(cls, name: str, data: TomlData) -> Experiment:
         return cls(args=data["args"], **cls._init_args_from_toml(name, data))
 
 
@@ -98,7 +100,7 @@ class ThirdPartyProject(BaseProject):
     tarball: TarballPackage
 
     @classmethod
-    def collect(cls) -> Iterator["ThirdPartyProject"]:
+    def collect(cls) -> Iterator[ThirdPartyProject]:
         for path in filter(lambda p: p.suffix == ".toml", REAL_PROJECTS_DIR.iterdir()):
             toml_data = parse_toml(path)
             project_info = cls._init_args_from_toml(toml_data, Experiment)

tests/test_sample_projects.py

@@ -19,6 +19,8 @@
     ├── expected.toml (mandatory)
     └── ... (regular Python project)
 """
+from __future__ import annotations
+
 import sys
 from dataclasses import dataclass
 from pathlib import Path
@@ -62,7 +64,7 @@ class Experiment(BaseExperiment):
     exclude: List[str]
 
     @classmethod
-    def from_toml(cls, name: str, data: TomlData) -> "Experiment":
+    def from_toml(cls, name: str, data: TomlData) -> Experiment:
         return cls(
             code=data.get("code", [""]),
             deps=data.get("deps", [""]),
@@ -103,7 +105,7 @@ class SampleProject(BaseProject):
     path: Path  # Directory containing expected.toml, and rest of sample project
 
     @classmethod
-    def collect(cls) -> Iterator["SampleProject"]:
+    def collect(cls) -> Iterator[SampleProject]:
         for subdir in SAMPLE_PROJECTS_DIR.iterdir():
             toml_path = subdir / "expected.toml"
             if not toml_path.is_file():