Handle has-a relationships for type-hinted arguments in class diagrams

ChangeLog

@@ -12,6 +12,10 @@ Release date: TBA
 ..
   Put bug fixes that should not wait for a new minor version here
 
+* pyreverse: Show class has-a relationships inferred from the type-hint
+
+Closes #4744
+
 * Added ``ignored-parents`` option to the design checker to ignore specific
   classes from the ``too-many-ancestors`` check (R0901).
 

doc/whatsnew/2.10.rst

@@ -40,6 +40,8 @@ Extensions
 Other Changes
 =============
 
+* Pyreverse - Show class has-a relationships inferred from type-hints
+
 * Performance of the Similarity checker has been improved.
 
 * Added ``time.clock`` to deprecated functions/methods for python 3.3

pylint/pyreverse/utils.py

@@ -269,9 +269,9 @@ def infer_node(node: Union[astroid.AssignAttr, astroid.AssignName]) -> set:
     otherwise return a set of the inferred types using the NodeNG.infer method"""
 
     ann = get_annotation(node)
-    if ann:
-        return {ann}
     try:
+        if ann:
+            return set(ann.infer())
         return set(node.infer())
     except astroid.InferenceError:
-        return set()
+        return {ann} if ann else set()

tests/data/classes_No_Name.dot

@@ -3,10 +3,12 @@ charset="utf-8"
 rankdir=BT
 "0" [label="{Ancestor|attr : str\lcls_member\l|get_value()\lset_value(value)\l}", shape="record"];
 "1" [label="{DoNothing|\l|}", shape="record"];
-"2" [label="{Interface|\l|get_value()\lset_value(value)\l}", shape="record"];
-"3" [label="{Specialization|TYPE : str\lrelation\ltop : str\l|}", shape="record"];
-"3" -> "0" [arrowhead="empty", arrowtail="none"];
-"0" -> "2" [arrowhead="empty", arrowtail="node", style="dashed"];
+"2" [label="{DoNothing2|\l|}", shape="record"];
+"3" [label="{Interface|\l|get_value()\lset_value(value)\l}", shape="record"];
+"4" [label="{Specialization|TYPE : str\lrelation\lrelation2\ltop : str\l|}", shape="record"];
+"4" -> "0" [arrowhead="empty", arrowtail="none"];
+"0" -> "3" [arrowhead="empty", arrowtail="node", style="dashed"];
 "1" -> "0" [arrowhead="diamond", arrowtail="none", fontcolor="green", label="cls_member", style="solid"];
-"1" -> "3" [arrowhead="diamond", arrowtail="none", fontcolor="green", label="relation", style="solid"];
+"1" -> "4" [arrowhead="diamond", arrowtail="none", fontcolor="green", label="relation", style="solid"];
+"2" -> "4" [arrowhead="diamond", arrowtail="none", fontcolor="green", label="relation2", style="solid"];
 }

tests/data/clientmodule_test.py

@@ -1,5 +1,5 @@
 """ docstring for file clientmodule.py """
-from data.suppliermodule_test import Interface, DoNothing
+from data.suppliermodule_test import Interface, DoNothing, DoNothing2
 
 class Ancestor:
     """ Ancestor method """
@@ -23,7 +23,8 @@ class Specialization(Ancestor):
     TYPE = 'final class'
     top = 'class'
 
-    def __init__(self, value, _id):
+    def __init__(self, value, _id, relation2: DoNothing2):
         Ancestor.__init__(self, value)
         self._id = _id
         self.relation = DoNothing()
+        self.relation2 = relation2

tests/data/suppliermodule_test.py

@@ -8,3 +8,5 @@ def set_value(self, value):
         raise NotImplementedError
 
 class DoNothing: pass
+
+class DoNothing2: pass

tests/unittest_pyreverse_diadefs.py

@@ -99,6 +99,7 @@ class TestDefaultDiadefGenerator:
     _should_rels = [
         ("association", "DoNothing", "Ancestor"),
         ("association", "DoNothing", "Specialization"),
+        ("association", "DoNothing2", "Specialization"),
         ("implements", "Ancestor", "Interface"),
         ("specialization", "Specialization", "Ancestor"),
     ]
@@ -142,6 +143,7 @@ def test_known_values1(HANDLER, PROJECT):
     assert classes == [
         (True, "Ancestor"),
         (True, "DoNothing"),
+        (True, "DoNothing2"),
         (True, "Interface"),
         (True, "Specialization"),
     ]
@@ -170,6 +172,7 @@ def test_known_values3(HANDLER, PROJECT):
         (True, "data.clientmodule_test.Ancestor"),
         (True, special),
         (True, "data.suppliermodule_test.DoNothing"),
+        (True, "data.suppliermodule_test.DoNothing2"),
     ]
 
 
@@ -184,6 +187,7 @@ def test_known_values4(HANDLER, PROJECT):
     assert classes == [
         (True, "Ancestor"),
         (True, "DoNothing"),
+        (True, "DoNothing2"),
         (True, "Specialization"),
     ]
 

tests/unittest_pyreverse_inspector.py

@@ -62,9 +62,9 @@ def test_instance_attrs_resolution(project):
     klass = project.get_module("data.clientmodule_test")["Specialization"]
     assert hasattr(klass, "instance_attrs_type")
     type_dict = klass.instance_attrs_type
-    assert len(type_dict) == 2
+    assert len(type_dict) == 3
     keys = sorted(type_dict.keys())
-    assert keys == ["_id", "relation"]
+    assert keys == ["_id", "relation", "relation2"]
     assert isinstance(type_dict["relation"][0], astroid.bases.Instance), type_dict[
         "relation"
     ]

tests/unittest_pyreverse_writer.py

@@ -204,3 +204,21 @@ def test_infer_node_2(mock_infer, mock_get_annotation):
     mock_infer.return_value = "x"
     assert infer_node(node) == set("x")
     assert mock_infer.called
+
+
+def test_infer_node_3():
+    """Return a set containing an astroid.ClassDef object when the attribute
+    has a type annotation"""
+    node = astroid.extract_node(
+        """
+        class Component:
+            pass
+
+        class Composite:
+            def __init__(self, component: Component):
+                self.component = component
+    """
+    )
+    instance_attr = node.instance_attrs.get("component")[0]
+    assert isinstance(infer_node(instance_attr), set)
+    assert isinstance(infer_node(instance_attr).pop(), astroid.ClassDef)