Improve partial execution

.coveragerc

@@ -0,0 +1,5 @@
+# https://coverage.readthedocs.io/en/coverage-5.0.4/config.html
+[run]
+# branch = True
+omit =
+    deal/linter/_template.py

.gitignore

@@ -5,7 +5,7 @@ __pycache__/
 dist/
 
 # coverage
-.coverage*
+.coverage
 coverage.xml
 htmlcov/
 

deal/linter/_contract.py

@@ -2,15 +2,13 @@
 import ast
 import builtins
 import enum
+from pathlib import Path
 
 # external
 import astroid
 
 
-TEMPLATE = """
-contract = PLACEHOLDER
-result = contract(*args, **kwargs)
-"""
+TEMPLATE = (Path(__file__).parent / '_template.py').read_text()
 
 
 class Category(enum.Enum):
@@ -21,14 +19,15 @@ class Category(enum.Enum):
 
 
 class Contract:
-    __slots__ = ('args', 'category')
+    __slots__ = ('args', 'category', 'func_args')
 
-    def __init__(self, args, category: Category):
+    def __init__(self, args, category: Category, func_args: ast.arguments = None):
         self.args = args
         self.category = category
+        self.func_args = func_args
 
     @property
-    def body(self):
+    def body(self) -> ast.AST:
         contract = self.args[0]
         # convert astroid node to ast node
         if hasattr(contract, 'as_string'):
@@ -67,12 +66,20 @@ def exceptions(self) -> list:
     @property
     def bytecode(self):
         module = ast.parse(TEMPLATE)
+
+        # inject function signature
+        if self.func_args is not None:
+            func = ast.parse('lambda:0').body[0].value
+            func.args = self.func_args
+            module.body[3].value = func
+
+        # inject contract
         contract = self.body
         if isinstance(contract, ast.FunctionDef):
             # if contract is function, add it's definition and assign it's name
             # to `contract` variable.
             module.body = [contract] + module.body
-            module.body[1].value = ast.Name(
+            module.body[3].value = ast.Name(
                 id=contract.name,
                 lineno=1,
                 col_offset=1,
@@ -81,7 +88,8 @@ def bytecode(self):
         else:
             if isinstance(contract, ast.Expr):
                 contract = contract.value
-            module.body[0].value = contract
+            module.body[2].value = contract
+
         return compile(module, filename='<ast>', mode='exec')
 
     def run(self, *args, **kwargs):

deal/linter/_func.py

@@ -1,7 +1,7 @@
 # built-in
 import ast
 from pathlib import Path
-from typing import Iterable, List
+from typing import Iterable, List, NamedTuple
 
 # external
 import astroid
@@ -11,21 +11,14 @@
 from ._extractors import get_contracts
 
 
-TEMPLATE = """
-contract = PLACEHOLDER
-result = contract(*args, **kwargs)
-"""
+class Func(NamedTuple):
+    name: str
+    args: ast.arguments
+    body: list
+    contracts: Iterable[Contract]
 
-
-class Func:
-    __slots__ = ('body', 'contracts', 'name', 'line', 'col')
-
-    def __init__(self, *, body: list, contracts: Iterable[Contract], name: str, line: int, col: int):
-        self.body = body
-        self.contracts = contracts
-        self.name = name
-        self.line = line
-        self.col = col
+    line: int
+    col: int
 
     @classmethod
     def from_path(cls, path: Path) -> List['Func']:
@@ -46,10 +39,15 @@ def from_ast(cls, tree: ast.Module) -> List['Func']:
                 continue
             contracts = []
             for category, args in get_contracts(expr.decorator_list):
-                contract = Contract(args=args, category=Category(category))
+                contract = Contract(
+                    args=args,
+                    category=Category(category),
+                    func_args=expr.args,
+                )
                 contracts.append(contract)
             funcs.append(cls(
                 name=expr.name,
+                args=expr.args,
                 body=expr.body,
                 contracts=contracts,
                 line=expr.lineno,
@@ -63,13 +61,25 @@ def from_astroid(cls, tree: astroid.Module) -> List['Func']:
         for expr in tree.body:
             if not isinstance(expr, astroid.FunctionDef):
                 continue
+
+            # make signature
+            code = 'def f({}):0'.format(expr.args.as_string())
+            func_args = ast.parse(code).body[0].args  # type: ignore
+
+            # collect contracts
             contracts = []
             if expr.decorators:
                 for category, args in get_contracts(expr.decorators.nodes):
-                    contract = Contract(args=args, category=Category(category))
+                    contract = Contract(
+                        args=args,
+                        func_args=func_args,
+                        category=Category(category),
+                    )
                     contracts.append(contract)
+
             funcs.append(cls(
                 name=expr.name,
+                args=func_args,
                 body=expr.body,
                 contracts=contracts,
                 line=expr.lineno,

deal/linter/_rules.py

@@ -8,9 +8,8 @@
 from ._contract import Category, Contract
 from ._error import Error
 from ._extractors import (
-    get_exceptions, get_exceptions_stubs, get_globals,
-    get_imports, get_prints, get_returns, get_asserts,
-    has_returns,
+    get_asserts, get_exceptions, get_exceptions_stubs, get_globals,
+    get_imports, get_prints, get_returns, has_returns,
 )
 from ._func import Func
 from ._stub import StubsManager

deal/linter/_template.py

@@ -0,0 +1,23 @@
+# This file is excluded from coverage.
+
+# project
+from deal import ContractError
+from deal._decorators.base import Base
+
+
+# will be filled from the linter
+contract = ...
+func = ...
+
+base = Base(validator=contract)  # type: ignore
+if func is not Ellipsis:
+    base.function = func
+
+try:
+    base.validate(*args, **kwargs)  # type: ignore  # noqa: F821
+except ContractError as exc:
+    result = False
+    if exc.args:
+        result = exc.args[0]
+else:
+    result = True

tests/test_linter/test_contract.py

@@ -95,3 +95,43 @@ def f(x):
     c = func.contracts[0]
     assert c.run(1) is True
     assert c.run(-1) is False
+
+
+def test_return_message():
+    text = """
+    import deal
+
+    @deal.post(lambda x: x > 0 or 'oh no!')
+    def f(x):
+        return x
+    """
+    text = dedent(text).strip()
+    funcs1 = Func.from_ast(ast.parse(text))
+    assert len(funcs1) == 1
+    funcs2 = Func.from_astroid(astroid.parse(text))
+    assert len(funcs2) == 1
+    for func in (funcs1[0], funcs2[0]):
+        assert len(func.contracts) == 1
+        c = func.contracts[0]
+        assert c.run(1) is True
+        assert c.run(-1) == 'oh no!'
+
+
+def test_simplified_signature():
+    text = """
+    import deal
+
+    @deal.post(lambda _: _.a > _.b)
+    def f(a, b):
+        return a + b
+    """
+    text = dedent(text).strip()
+    funcs1 = Func.from_ast(ast.parse(text))
+    assert len(funcs1) == 1
+    funcs2 = Func.from_astroid(astroid.parse(text))
+    assert len(funcs2) == 1
+    for func in (funcs1[0], funcs2[0]):
+        assert len(func.contracts) == 1
+        c = func.contracts[0]
+        assert c.run(3, 2) is True
+        assert c.run(2, 3) is False

tests/test_linter/test_rules.py

@@ -8,7 +8,7 @@
 # project
 from deal.linter._func import Func
 from deal.linter._rules import (
-    CheckImports, CheckPrints, CheckPure, CheckRaises, CheckReturns, rules, CheckAsserts,
+    CheckAsserts, CheckImports, CheckPrints, CheckPure, CheckRaises, CheckReturns, rules,
 )