models/package: have `version_spec` only exist in `ReqPackage` (#303)

src/pipdeptree/_models/package.py

@@ -39,10 +39,6 @@ class Package(ABC):
     def as_dict(self) -> dict[str, str | None]:
         raise NotImplementedError
 
-    @property
-    def version_spec(self) -> None | str:
-        return None
-
     def render(
         self,
         parent: DistPackage | ReqPackage | None = None,

src/pipdeptree/_render/json_tree.py

@@ -4,8 +4,10 @@ import json
 from itertools import chain
 from typing import TYPE_CHECKING, Any
 
+from pipdeptree._models import ReqPackage
+
 if TYPE_CHECKING:
-    from pipdeptree._models import DistPackage, PackageDAG, ReqPackage
+    from pipdeptree._models import DistPackage, PackageDAG
 
 
 def render_json_tree(tree: PackageDAG) -> str:
@@ -37,7 +39,7 @@ def render_json_tree(tree: PackageDAG) -> str:
 
         d: dict[str, str | list[Any] | None] = node.as_dict()  # type: ignore[assignment]
         if parent:
-            d["required_version"] = node.version_spec if node.version_spec else "Any"
+            d["required_version"] = node.version_spec if isinstance(node, ReqPackage) and node.version_spec else "Any"
         else:
             d["required_version"] = d["installed_version"]
 

tests/render/test_json_tree.py

@@ -0,0 +1,34 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Callable, Iterator
+
+import pytest
+
+from pipdeptree._models.dag import PackageDAG
+from pipdeptree._render.json_tree import render_json_tree
+
+if TYPE_CHECKING:
+    from unittest.mock import Mock
+
+    from tests.our_types import MockGraph
+
+
+@pytest.mark.parametrize(
+    ("version_spec_tuple", "expected_version_spec"),
+    [
+        pytest.param((), "Any"),
+        pytest.param((">=", "2.0.0"), ">=2.0.0"),
+    ],
+)
+def test_json_tree_given_req_package_with_version_spec(
+    mock_pkgs: Callable[[MockGraph], Iterator[Mock]],
+    version_spec_tuple: tuple[str, str],
+    expected_version_spec: str,
+) -> None:
+    graph: dict[tuple[str, str], list[tuple[str, list[tuple[str, str]]]]] = {
+        ("a", "1.2.3"): [("b", [version_spec_tuple])],
+        ("b", "2.2.0"): [],
+    }
+    package_dag = PackageDAG.from_pkgs(list(mock_pkgs(graph)))
+    json_tree_str = render_json_tree(package_dag)
+    assert json_tree_str.find(expected_version_spec) != -1