Add ClassVar support for dataclass

jedi/inference/value/klass.py

@@ -146,6 +146,10 @@ def get_dataclass_param_names(cls):
         d = name.tree_name.get_definition()
         annassign = d.children[1]
         if d.type == 'expr_stmt' and annassign.type == 'annassign':
+            node = annassign.children[1]
+            if node.type == "atom_expr" and node.children[0].value == "ClassVar":
+                continue
+
             if len(annassign.children) < 4:
                 default = None
             else:

test/test_inference/test_signature.py

@@ -392,13 +392,18 @@ def test_dataclass_signature(
         """
             name: str
             foo = 3
+            blob: ClassVar[str]
             price: float
             quantity: int = 0.0
 
         X("""
     )
 
-    code = 'from dataclasses import dataclass\n' + start + code
+    code = (
+        "from dataclasses import dataclass\nfrom typing import ClassVar\n"
+        + start
+        + code
+    )
 
     sig, = Script(code).get_signatures()
     expected_params = (