Add 'changed function implementation' detection

pyff/pyff.py

@@ -1,18 +1,29 @@
 """Functions for comparison of various Python entities"""
 
-from ast import FunctionDef, parse, NodeVisitor, Module
-from typing import cast, Set
+from ast import FunctionDef, parse, NodeVisitor, Module, dump
+from typing import cast, Set, Dict
 from collections import defaultdict
+from itertools import zip_longest
 
 import pyff.pyfference as pf
 from pyff.summary import ClassSummary
 
 def _pyff_function_ast(first: FunctionDef, second: FunctionDef) -> pf.FunctionPyfference:
     """Return differences between two Python function ASTs, or None if they are identical"""
-    if first.name == second.name:
-        return None
+    names = None
+    if first.name != second.name:
+        names = (first.name, second.name)
 
-    return pf.FunctionPyfference(names=(first.name, second.name))
+    implementation = None
+    for old_statement, new_statement in zip_longest(first.body, second.body):
+        if dump(old_statement) != dump(new_statement):
+            implementation = True
+            break
+
+    if names or implementation:
+        return pf.FunctionPyfference(name=first.name, names=names, implementation=implementation)
+
+    return None
 
 def _pyff_from_imports(first_ast: Module, second_ast: Module) -> pf.FromImportPyfference:
     """Return differences in `from X import Y` statements in two modules"""
@@ -61,12 +72,47 @@ def _pyff_classes(first_ast: Module, second_ast: Module) -> pf.ClassesPyfference
 
     return pf.ClassesPyfference(appeared) if appeared else None
 
+class MethodsExtractor(NodeVisitor):
+    """Extract information about methods in a module"""
+    def __init__(self) -> None:
+        self.names: Set[str] = set()
+        self.functions: Dict[str, FunctionDef] = {}
+
+    def visit_ClassDef(self, node): # pylint: disable=invalid-name
+        """Prevent this visitor from inspecting classes"""
+        pass
+
+    def visit_FunctionDef(self, node): # pylint: disable=invalid-name
+        """Save top-level function definitions"""
+        self.names.add(node.name)
+        self.functions[node.name] = node
+
+def _pyff_functions(first_ast: Module, second_ast: Module) -> pf.FunctionsPyfference:
+    """Return differences in top-level functions in two modules"""
+    first_walker = MethodsExtractor()
+    second_walker = MethodsExtractor()
+
+    first_walker.visit(first_ast)
+    second_walker.visit(second_ast)
+
+    both = first_walker.names.intersection(second_walker.names)
+    differences = {}
+    for function in both:
+        difference = _pyff_function_ast(first_walker.functions[function],
+                                        second_walker.functions[function])
+        if difference:
+            differences[function] = difference
+
+    return pf.FunctionsPyfference(changed=differences) if differences else None
+
+
 def _pyff_modules(first_ast: Module, second_ast: Module) -> pf.ModulePyfference:
     from_imports = _pyff_from_imports(first_ast, second_ast)
     classes = _pyff_classes(first_ast, second_ast)
+    functions = _pyff_functions(first_ast, second_ast)
 
-    if from_imports or classes:
-        return pf.ModulePyfference(from_imports, classes)
+    if from_imports or classes or functions:
+        return pf.ModulePyfference(from_imports, classes, functions)
 
     return None
 

pyff/pyfference.py

@@ -7,17 +7,35 @@
 
 class FunctionPyfference:  # pylint: disable=too-few-public-methods
     """Holds differences between Python function definitions"""
-    def __init__(self, names: Tuple[str, str] = None) -> None:
-        self.name: Change = None
-        self.changes: List[Change] = []
+    def __init__(self, name: str, names: Tuple[str, str] = None,
+                 implementation: bool = None) -> None:
+        self.name = name
+        self.names: Change = None
+        self.changes: List = []
+        self.implementation: bool = implementation
 
         if names:
-            self.name = Change(names[0], names[1])
-            self.changes.append(self.name)
+            self.names = Change(names[0], names[1])
+            self.changes.append(self.names)
+
+        if implementation:
+            self.changes.append(f"Function '{self.name}' changed implementation")
 
     def __len__(self):
         return len(self.changes)
 
+    def __str__(self):
+        if self.names and self.implementation:
+            old = self.names.old
+            new = self.names.new
+            return f"Function '{old}' was renamed to '{new}' and its implementation changed"
+        elif self.names:
+            return f"Function '{self.names.old}' was renamed to '{self.names.new}'"
+        elif self.implementation:
+            return f"Function '{self.name}' changed implementation"
+
+        return ""
+
 class FromImportPyfference: # pylint: disable=too-few-public-methods
     """Holds differences between from X import Y statements in a module"""
     def __init__(self, new: Dict[str, List[str]]) -> None:
@@ -32,7 +50,17 @@ def __str__(self):
 
         return "\n".join(lines)
 
+class FunctionsPyfference: # pylint: disable=too-few-public-methods
+    """Holds differences between top-level functions in a module"""
+    def __init__(self, changed: Dict[str, FunctionPyfference]) -> None:
+        self.changed = changed
+
+    def __str__(self) -> str:
+
+        return "\n".join([str(change) for change in self.changed.values()])
+
 class ClassesPyfference: # pylint: disable=too-few-public-methods
+
     """Holds differences between classes defined in a module"""
     def __init__(self, new: Iterable[ClassSummary]) -> None:
         self.new: Iterable[ClassSummary] = new
@@ -43,10 +71,12 @@ def __str__(self):
 class ModulePyfference:  # pylint: disable=too-few-public-methods
     """Holds differences between two Python modules"""
     def __init__(self, from_imports: FromImportPyfference = None,
-                 classes: ClassesPyfference = None) -> None:
+                 classes: ClassesPyfference = None,
+                 functions: FunctionsPyfference = None) -> None:
         self.changes: List = []
         self.from_imports: FromImportPyfference = None
         self.classes: ClassesPyfference = None
+        self.functions: FunctionsPyfference = None
 
         if from_imports:
             self.from_imports = from_imports
@@ -56,6 +86,10 @@ def __init__(self, from_imports: FromImportPyfference = None,
             self.classes = classes
             self.changes.append(self.classes)
 
+        if functions:
+            self.functions = functions
+            self.changes.append(self.functions)
+
     def __len__(self):
         return len(self.changes)
 

tests/unit/test_functions.py

@@ -6,6 +6,7 @@
 TRIVIAL_FUNCTION = """def function(): pass"""
 TRIVIAL_FUNCTION_2 = """def function2(): pass"""
 
+IMPLEMENTED_FUNCTION = """def function(): return None"""
 
 def test_trivial_function():
     difference = pyff_function(TRIVIAL_FUNCTION, TRIVIAL_FUNCTION)
@@ -14,9 +15,10 @@ def test_trivial_function():
 def test_name_change():
     difference = pyff_function(TRIVIAL_FUNCTION, TRIVIAL_FUNCTION_2)
     assert len(difference) == 1
-    assert difference.name is not None
-    assert difference.name.old == "function"
-    assert difference.name.new == "function2"
+    assert difference.name == "function"
+    assert difference.names is not None
+    assert difference.names.old == "function"
+    assert difference.names.new == "function2"
 
 def test_not_functions():
     no_func = "a = 1"
@@ -28,3 +30,10 @@ def g(): pass"""
             pyff_function(TRIVIAL_FUNCTION, bad)
         with raises(ValueError):
             pyff_function(bad, TRIVIAL_FUNCTION)
+
+def test_changed_implementation():
+    difference = pyff_function(TRIVIAL_FUNCTION, IMPLEMENTED_FUNCTION)
+    assert len(difference) == 1
+    assert difference.names is None
+    assert difference.implementation is not None
+    assert str(difference) == "Function 'function' changed implementation"

tests/unit/test_modules.py

@@ -3,27 +3,27 @@
 from pyff.pyff import pyff_module
 
 TRIVIAL_MODULE = """import sys
-
 def func():
     pass"""
 
 IMPORT_MODULE = """import sys
 from os import path
-
 def func():
     pass"""
 
 CLASSES_MODULE = """import sys
-
 class Klass:
     def method(self):
         pass
     def _method(self):
         pass
-
 def func():
     pass"""
 
+CHANGED_FUNCTION_MODULE = """import sys
+def func():
+    return None"""
+
 
 def test_trivial_module():
     difference = pyff_module(TRIVIAL_MODULE, TRIVIAL_MODULE)
@@ -40,3 +40,9 @@ def test_module_with_new_class():
     assert difference is not None
     assert len(difference) == 1
     assert str(difference) == "New class 'Klass' with 1 public methods"
+
+def test_module_with_changed_function(): # pylint: disable=invalid-name
+    difference = pyff_module(TRIVIAL_MODULE, CHANGED_FUNCTION_MODULE)
+    assert difference is not None
+    assert len(difference) == 1
+    assert str(difference) == "Function 'func' changed implementation"