Verify nodes' str() and repr() don't raise errors/warnings

Calling str() or repr() on certain nodes fails either with errors
or warnings. A unittest was added to verify this behaviour and find
the offending nodes. Code has been corrected, mainly by
accesing node's attributes safely and using placeholders if necessary.

Closes  #1881

Author: crazybolillo

astroid/nodes/node_classes.py

@@ -859,33 +859,33 @@ def find_argname(self, argname, rec=False):
         return None, None
 
     def get_children(self):
-        yield from self.posonlyargs or ()
+        yield from getattr(self, "posonlyargs", ())
 
-        for elt in self.posonlyargs_annotations:
+        for elt in getattr(self, "posonlyargs_annotations", False) or ():
             if elt is not None:
                 yield elt
 
-        yield from self.args or ()
+        yield from getattr(self, "args", ())
 
-        if self.defaults is not None:
+        if getattr(self, "defaults", None) is not None:
             yield from self.defaults
-        yield from self.kwonlyargs
+        yield from getattr(self, "kwonlyargs", ())
 
-        for elt in self.kw_defaults or ():
+        for elt in getattr(self, "kw_defaults", False) or ():
             if elt is not None:
                 yield elt
 
-        for elt in self.annotations:
+        for elt in getattr(self, "annotations", False) or ():
             if elt is not None:
                 yield elt
 
-        if self.varargannotation is not None:
+        if getattr(self, "varargannotation", None) is not None:
             yield self.varargannotation
 
-        if self.kwargannotation is not None:
+        if getattr(self, "kwargannotation", None) is not None:
             yield self.kwargannotation
 
-        for elt in self.kwonlyargs_annotations:
+        for elt in getattr(self, "kwonlyargs_annotations", False) or ():
             if elt is not None:
                 yield elt
 

astroid/nodes/node_ng.py

@@ -210,7 +210,7 @@ def __str__(self) -> str:
             alignment = len(cname) + 1
         result = []
         for field in self._other_fields + self._astroid_fields:
-            value = getattr(self, field)
+            value = getattr(self, field, "Unknown")
             width = 80 - len(field) - alignment
             lines = pprint.pformat(value, indent=2, width=width).splitlines(True)
 
@@ -227,14 +227,18 @@ def __str__(self) -> str:
 
     def __repr__(self) -> str:
         rname = self.repr_name()
+        try:
+            lineno = self.fromlineno
+        except AttributeError:
+            lineno = 0
         if rname:
             string = "<%(cname)s.%(rname)s l.%(lineno)s at 0x%(id)x>"
         else:
             string = "<%(cname)s l.%(lineno)s at 0x%(id)x>"
         return string % {
             "cname": type(self).__name__,
             "rname": rname,
-            "lineno": self.fromlineno,
+            "lineno": lineno,
             "id": id(self),
         }
 

astroid/nodes/scoped_nodes/scoped_nodes.py

@@ -1350,7 +1350,7 @@ def fromlineno(self) -> int:
         # lineno is the line number of the first decorator, we want the def
         # statement lineno. Similar to 'ClassDef.fromlineno'
         lineno = self.lineno or 0
-        if self.decorators is not None:
+        if getattr(self, "decorators", None) is not None:
             lineno += sum(
                 node.tolineno - (node.lineno or 0) + 1 for node in self.decorators.nodes
             )

tests/test_nodes.py

@@ -7,7 +7,9 @@
 from __future__ import annotations
 
 import copy
+import inspect
 import os
+import random
 import sys
 import textwrap
 import unittest
@@ -1880,3 +1882,36 @@ def return_from_match(x):
         inferred = node.inferred()
         assert len(inferred) == 2
         assert [inf.value for inf in inferred] == [10, -1]
+
+
+@pytest.mark.parametrize(
+    "node",
+    list(
+        filter(
+            lambda node: node.__name__
+            not in ["_BaseContainer", "BaseContainer", "NodeNG", "const_factory"],
+            astroid.nodes.ALL_NODE_CLASSES,
+        )
+    ),
+)
+@pytest.mark.filterwarnings("error")
+def test_str_repr_no_warnings(node):
+    parameters = inspect.signature(node.__init__).parameters
+
+    args = {}
+    for name, param_type in parameters.items():
+        if name == "self":
+            continue
+
+        if "int" in param_type.annotation:
+            args[name] = random.randint(0, 50)
+        elif "NodeNG" in param_type.annotation:
+            args[name] = nodes.Unknown()
+        elif "str" in param_type.annotation:
+            args[name] = ""
+        else:
+            args[name] = None
+
+    test_node = node(**args)
+    str(test_node)
+    repr(test_node)