Fix pattern matching and add unit tests

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "design-by-contract"
-version = "0.2"
+version = "0.2.1"
 description = "Handy decorator to define contracts with dependency injection in Python 3.10 and above"
 authors = ["Stefan Ulbrich"]
 license = "MIT"

src/design_by_contract.py

@@ -23,6 +23,7 @@ class UnresolvedSymbol:
  Overrides the equality operator to behave like an
  assignment.
  """
+
  name: str
  value: Optional[Any] = None
 
@@ -32,11 +33,15 @@ def __eq__(self, other: Any) -> "UnresolvedSymbol":
  if self.value is None:
  raise ContractViolationError(f"Symbols `{self.name}` and `{other.name}` undefined")
  other.value = self.value
- case UnresolvedSymbol(value) if value != self.value:
+ case UnresolvedSymbol(_, value) if self.value is None:
+ self.value = value
+ case UnresolvedSymbol(name, value) if value != self.value:
  raise ContractViolationError(
- f"Symbols `{self.name}` and `{other.name}` do not match: `{self.value}` != `{other.value}`"
+ f"Symbols `{self.name}` and `{name}` do not match: `{self.value}` != `{value}`"
  )
- case value if value != value:
+ case self.value:
+ return True
+ case value if self.value is not None:
  raise ContractViolationError(
  f"Symbols `{self.name}` and `{other}` do not match: `{self.value}` != `{other}`"
  )
@@ -45,13 +50,12 @@ def __eq__(self, other: Any) -> "UnresolvedSymbol":
  return self
 
  def __bool__(self) -> bool:
- return (self.value is not None)
+ return self.value is not None
 
 
 P, R = ParamSpec("P"), TypeVar("R")
 
 
-#: Test
 @decorator
 def contract(
  func: Callable[P, R],
@@ -73,7 +77,6 @@ def contract(
  If False, the contracts are not evaluated, by default True
  """
 
-
  if not evaluate:
  return func(*args, **kw)
 
@@ -117,11 +120,11 @@ def evaluate_annotations(annotations: dict[str, Any]) -> None:
 
  logger.debug("contract for `%s`, unresolved: `%s`, %s", arg_name, unresolved, symbols)
 
- if  not meta(*[(symbols | injectables)[i] for i in meta_args]):
+ if not meta(*[(symbols | injectables)[i] for i in meta_args]):
  raise ContractViolationError(f"Contract violated for argument: `{arg_name}`")
 
  if any([i.value is None for i in symbols.values()]):
- raise ContractLogicError(f"Not all symbols were resolved `%s`", symbols)
+ raise ContractLogicError(f"Not all symbols were resolved `{symbols}`", )
 
  injectables |= {k: v.value for k, v in symbols.items()}
 
@@ -146,6 +149,7 @@ def evaluate_annotations(annotations: dict[str, Any]) -> None:
 
 
 if __name__ == "__main__":
+ # pylint: disable=invalid-name, missing-function-docstring
  # Example
  import numpy as np
 

tests/test_dbc.py

@@ -4,9 +4,9 @@
 import numpy as np
 import pandas as pd
 import pytest
-from design_by_contract import contract, ContractViolationError, ContractLogicError
-
+from design_by_contract import contract, ContractViolationError, ContractLogicError, UnresolvedSymbol
 
+# pylint: skip-file
 class TestNumpy:
  def test_matmult_correct(self):
  @contract
@@ -115,15 +115,16 @@ def spam(
  assert str(exc_info.value) == ("Contract violated for argument: `a`")
 
  def test_vstack(self):
-
  @contract
  def spam(
  a: Annotated[np.ndarray, lambda x, m, o: (m, o) == x.shape],
  b: Annotated[np.ndarray, lambda x, n, o: (n, o) == x.shape],
- ) -> Annotated[np.ndarray, lambda x, m,n,o: x.shape == (m+n, o)]:
- print(np.vstack((a,b)).shape)
- return np.vstack((a,b))
- spam(np.zeros((3, 2)), np.zeros(( 4, 2)))
+ ) -> Annotated[np.ndarray, lambda x, m, n, o: x.shape == (m + n, o)]:
+ print(np.vstack((a, b)).shape)
+ return np.vstack((a, b))
+
+ spam(np.zeros((3, 2)), np.zeros((4, 2)))
+
 
 class TestGeneral:
  def test_docstring(self):
@@ -141,6 +142,50 @@ def spam(a: np.ndarray, b: Annotated[np.ndarray, lambda b, m: b.shape == (m, 3)]
 
  assert "(a: numpy.ndarray, b: typing.Annotated[numpy.ndarray," in str(signature(spam))
 
+ def test_reserved(self):
+ @contract(reserved="y")
+ def spam(
+ a: Annotated[np.ndarray, lambda y, m, n: (m, n) == y.shape],
+ b: Annotated[np.ndarray, lambda y, n, o: (n, o) == y.shape],
+ ) -> Annotated[np.ndarray, lambda y, m, o: y.shape == (m, o)]:
+
+ return a @ b
+
+ def test_match(self):
+ a, b = UnresolvedSymbol("a"), UnresolvedSymbol("b")
+ a == 2
+ b == a
+ assert a.value == b.value
+
+ def test_match_fail(self):
+ a, b = UnresolvedSymbol("a"), UnresolvedSymbol("b")
+ a == 2
+ b == 1
+ with pytest.raises(ContractViolationError) as exc_info:
+ a == b
+
+ def test_match_symmetry(self):
+ a, b = UnresolvedSymbol("a"), UnresolvedSymbol("b")
+ a == 2
+ assert a.value == 2
+
+ b = UnresolvedSymbol("a")
+ 2 == b
+ assert b.value == 2
+
+ def test_match_fail2(self):
+ a = UnresolvedSymbol("a")
+ a == 2
+
+ with pytest.raises(ContractViolationError) as exc_info:
+ a == 3
+
+ with pytest.raises(ContractViolationError) as exc_info:
+ 3 == a
+
+ a == 2
+ 2 == a
+
 
 class TestPandas:
  def test_pandas_correct(self):