test: stream api

.gitignore

@@ -7,6 +7,7 @@
 
 # Python
 __pycache__
+.hypothesis
 .venv
 
 # Coverage

README.md

@@ -4,8 +4,7 @@ Persil is a pure-python parsing library that draws much (most, let's be honest)
 of its inspiration from the excellent [Parsy](https://github.com/python-parsy/parsy) library.
 
 Hence the name, "Persil" ([pɛʁ.sil] or [pɛʁ.si]), the French word for parsley
--a most questionable pun on `Parsy -> Parsley -> Persil`,
-in case anyone missed it.
+-a most questionable pun on `Parsy -> Parsley -> Persil`, in case anyone missed it.
 
 Like Parsy, Persil is a _"monadic parser combinator library for LL(infinity) grammars"_.
 As a rough approximation, you can think of Persil as a typed "fork" of Parsy.

persil/stream.py

@@ -9,7 +9,9 @@
 
 
 class SoftError(Exception):
-    inner: Err
+    def __init__(self, inner: Err) -> None:
+        self.inner = inner
+        super().__init__()
 
 
 class Stream(Generic[In]):

pyproject.toml

@@ -17,14 +17,19 @@ pre-commit = "^3.7.0"
 mypy = "^1.9.0"
 pytest = "^8.1.1"
 pytest-cov = "^5.0.0"
-pydantic = "^2.6.4"
 
 
 [tool.poetry.group.docs.dependencies]
 mkdocs-material = "^9.5.18"
 mkdocstrings = {extras = ["python"], version = "^0.24.3"}
 mike = "^2.0.0"
 
+
+[tool.poetry.group.tests.dependencies]
+pytest = "^8.1.1"
+pytest-cov = "^5.0.0"
+hypothesis = "^6.100.1"
+
 [build-system]
 requires = ["poetry-core"]
 build-backend = "poetry.core.masonry.api"

tests/test_from_stream.py

@@ -1,30 +1,29 @@
-import pytest
-from pydantic import BaseModel
-
-from persil import regex
-from persil.stream import Stream, from_stream
+from datetime import datetime
 
+from hypothesis import given
+from hypothesis import strategies as st
 
-class Flight(BaseModel):
-    carrier: str
-    flight_number: int
-
+from persil import regex, string
+from persil.stream import Stream, from_stream
 
-@from_stream("Flight parser")
-def flight_parser(stream: Stream[str]) -> Flight:
-    carrier = stream.apply(regex(r"[A-Z]{2}"))
-    flight_number = stream.apply(regex(r"\d{2,4}").map(int))
+year_parser = regex(r"\d{4}").map(int)
+month_parser = regex(r"(?:0\d|1[012])").map(int)
+day_parser = regex(r"(?:[012]\d|3[01])").map(int)
 
-    return Flight(carrier=carrier, flight_number=flight_number)
 
+@from_stream
+def datetime_parser(stream: Stream[str]) -> datetime:
+    year = stream.apply(year_parser)
+    stream.apply(string("-"))
+    month = stream.apply(month_parser)
+    stream.apply(string("-"))
+    day = stream.apply(day_parser)
 
-EXAMPLES = [
-    ("AF071", Flight(carrier="AF", flight_number=71)),
-    ("LY180", Flight(carrier="LY", flight_number=180)),
-]
+    return datetime(year, month, day)
 
 
-@pytest.mark.parametrize("message,expected", EXAMPLES)
-def test_generate(message: str, expected: Flight):
-    flight = flight_parser.parse(message)
-    assert flight == expected
+@given(st.datetimes())
+def test_generate(dt: datetime):
+    dt = datetime(dt.year, dt.month, dt.day)
+    text = dt.strftime("%Y-%m-%d")
+    assert datetime_parser.parse(text) == dt