test: add multiple new test cases and update python version

1. update .python-version from 3.11 to 3.13
2. add tests for IS_RUNNING and DIR_EXISTS conditions
3. add graph-related tests including string ref parsing, mermaid output, GraphComposer and compose function
4. add storage backend TTL tests for both MemoryBackend and JSONBackend
5. add new system task tests for clr, reset_icon_cache, setenv and which
6. add comprehensive task spec tests including soft dependencies, retry policy, context managers and task template
7. add executor edge case tests for various scenarios

tests/test_graph.py

@@ -6,6 +6,7 @@ import pytest
 
 import pyflowx as px
 from pyflowx.errors import CycleError, DuplicateTaskError, MissingDependencyError
+from pyflowx.graph import GraphComposer, compose
 
 
 def _fn() -> None:
@@ -213,3 +214,115 @@ def test_subgraph_by_tags_no_match() -> None:
     graph = px.Graph.from_specs([px.TaskSpec("a", _fn, tags=("x",))])
     sub = graph.subgraph(["z"])
     assert len(sub) == 0
+
+
+# ---------------------------------------------------------------------- #
+# from_specs str 类型分支测试
+# ---------------------------------------------------------------------- #
+def test_from_specs_with_string_ref() -> None:
+    """from_specs 接受字符串引用并收集到 pending_refs."""
+    # 字符串引用被收集到 _pending_refs，而非尝试打开文件
+    graph = px.Graph.from_specs(["ref_cmd"])
+    assert graph._pending_refs == ["ref_cmd"]
+
+
+def test_from_specs_with_invalid_type() -> None:
+    """from_specs 接受不支持的类型时应抛 TypeError."""
+    with pytest.raises(TypeError, match="from_specs 只接受 TaskSpec 或 str"):
+        _ = px.Graph.from_specs([123])  # type: ignore[list-item]
+
+
+# ---------------------------------------------------------------------- #
+# to_mermaid 软依赖测试
+# ---------------------------------------------------------------------- #
+def test_to_mermaid_soft_depends_on() -> None:
+    """to_mermaid 应正确绘制软依赖为虚线."""
+    graph = px.Graph.from_specs([
+        px.TaskSpec("a", _fn),
+        px.TaskSpec("b", _fn, soft_depends_on=("a",)),
+    ])
+    mermaid = graph.to_mermaid()
+    assert "a -.-> b" in mermaid  # 软依赖用虚线
+
+
+# ---------------------------------------------------------------------- #
+# GraphComposer 与 compose 测试
+# ---------------------------------------------------------------------- #
+def test_graph_composer_resolve_all() -> None:
+    """GraphComposer.resolve_all 应展开所有图的字符串引用."""
+    graph_a = px.Graph.from_specs([px.TaskSpec("a1", _fn), px.TaskSpec("a2", _fn, depends_on=("a1",))])
+    # 创建带 _pending_refs 的图
+    graph_b = px.Graph.from_specs([px.TaskSpec("b1", _fn)])
+    graph_b._pending_refs = ["cmd_a"]  # 手动设置内部属性
+
+    composer = GraphComposer({"cmd_a": graph_a, "cmd_b": graph_b})
+    resolved = composer.resolve_all()
+
+    # graph_b 应包含 graph_a 的任务
+    assert "a1" in resolved["cmd_b"]
+    assert "a2" in resolved["cmd_b"]
+
+
+def test_graph_composer_parse_ref_self_reference() -> None:
+    """GraphComposer.parse_ref 应检测循环引用."""
+    graph = px.Graph.from_specs([px.TaskSpec("a", _fn)])
+    composer = GraphComposer({"cmd": graph})
+    with pytest.raises(ValueError, match="循环引用"):
+        _ = composer.parse_ref("cmd", "cmd")
+
+
+def test_graph_composer_parse_ref_cmd_not_found() -> None:
+    """GraphComposer.parse_ref 应检测引用的命令不存在."""
+    graph = px.Graph.from_specs([px.TaskSpec("a", _fn)])
+    composer = GraphComposer({"cmd": graph})
+    with pytest.raises(ValueError, match="引用的命令 'missing' 不存在"):
+        _ = composer.parse_ref("missing", "current")
+
+
+def test_graph_composer_parse_ref_task_not_found() -> None:
+    """GraphComposer.parse_ref 应检测任务不存在于引用的命令中."""
+    graph_a = px.Graph.from_specs([px.TaskSpec("a1", _fn)])
+    graph_b = px.Graph.from_specs([px.TaskSpec("b1", _fn)])
+    composer = GraphComposer({"cmd_a": graph_a, "cmd_b": graph_b})
+    with pytest.raises(ValueError, match="任务 'missing' 不存在于命令 'cmd_a' 中"):
+        _ = composer.parse_ref("cmd_a.missing", "cmd_b")
+
+
+def test_graph_composer_expand_refs_no_pending() -> None:
+    """GraphComposer.expand_refs 无 pending_refs 时应原样返回."""
+    graph = px.Graph.from_specs([px.TaskSpec("a", _fn)])
+    composer = GraphComposer({"cmd": graph})
+    expanded = composer.expand_refs(graph, "cmd")
+    assert expanded is graph
+
+
+def test_compose_function() -> None:
+    """compose() 函数应等同于 GraphComposer().resolve_all()。"""
+    graph_a = px.Graph.from_specs([px.TaskSpec("a1", _fn)])
+    graph_b = px.Graph.from_specs([px.TaskSpec("b1", _fn)])
+    graph_b._pending_refs = ["cmd_a"]  # 手动设置内部属性
+
+    resolved = compose({"cmd_a": graph_a, "cmd_b": graph_b})
+    assert "a1" in resolved["cmd_b"]
+
+
+# ---------------------------------------------------------------------- #
+# resolved_spec defaults 测试
+# ---------------------------------------------------------------------- #
+def test_resolved_spec_applies_defaults() -> None:
+    """resolved_spec 应应用 Graph.defaults。"""
+    defaults = px.GraphDefaults(timeout=10.0, retry=px.RetryPolicy(max_attempts=2))
+    graph = px.Graph.from_specs([px.TaskSpec("a", _fn)], defaults=defaults)
+
+    resolved = graph.resolved_spec("a")
+    assert resolved.timeout == 10.0
+    assert resolved.retry.max_attempts == 2
+
+
+def test_resolved_spec_no_override() -> None:
+    """resolved_spec 不应覆盖任务已有的设置。"""
+    defaults = px.GraphDefaults(timeout=10.0)
+    graph = px.Graph.from_specs([px.TaskSpec("a", _fn, timeout=5.0)], defaults=defaults)
+
+    resolved = graph.resolved_spec("a")
+    assert resolved.timeout == 5.0  # 保持原值，不被 defaults 覆盖