[CI][BugFix] Isolate controller mock to instance level

[EmmonsCurse]

Motivation

The cache controller unit test was affected by cross-test interference caused by mocking _free_host_cache at the class level or in a shared scope.

When MagicMock is applied globally, previously created controller instances (from earlier tests or garbage collection remnants) may still reference the original method or a shared mock state. This leads to non-deterministic behavior in __del__() execution paths and inconsistent call tracking.

Modifications

• Moved MagicMock assignment from global/class scope to instance scope:
  • controller._free_host_cache = MagicMock()
• Ensured the mock is stored in the instance __dict__, so only the current test instance is affected.
• Preserved original behavior for other controller instances that do not define _free_host_cache, allowing them to execute the real class method.
• Isolated destructor behavior (__del__) to avoid interference from stale or previously collected objects.
• Improved test determinism by fully decoupling mock lifecycle from other instances and tests.

Usage or Command

N/A

Accuracy Tests

N/A

Checklist

• Add at least a tag in the PR title.
  • Tag list: [[FDConfig],[APIServer],[Engine], [Scheduler], [PD Disaggregation], [Executor], [Graph Optimization], [Speculative Decoding], [RL], [Models], [Quantization], [Loader], [OP], [KVCache], [DataProcessor], [BugFix], [Docs], [CI], [Optimization], [Feature], [Benchmark], [Others], [XPU], [HPU], [GCU], [DCU], [Iluvatar], [Metax]]
  • You can add new tags based on the PR content, but the semantics must be clear.
• Format your code, run pre-commit before commit.
• Add unit tests. Please write the reason in this PR if no unit tests.
• Provide accuracy results.
• If the current PR is submitting to the release branch, make sure the PR has been submitted to the develop branch, then cherry-pick it to the release branch with the [Cherry-Pick] PR tag.

[EmmonsCurse]

/skip-ci ci_iluvatar
/skip-ci ci_hpu
/skip-ci build_xpu
/skip-ci pre_ce_test
/skip-ci stable_test
/skip-ci base_test
/skip-ci logprob_test
/skip-ci gpu_4cards_test

[PaddlePaddle-bot]

🤖 Paddle-CI-Agent | pr_review | 2026-07-02 13:28:46

📋 Review 摘要

PR 概述：将 CacheController 析构器单测中的 _free_host_cache mock 从类级 patch 改为当前 controller 实例属性，降低跨测试析构调用对 mock 计数的干扰。
变更范围：tests/cache_manager/v1/test_cache_controller.py
影响面 Tag：[KVCache]

问题

未发现阻塞性问题。PR 规范问题在下面章节报，不在这里重复。

📝 PR 规范检查

标题包含 [CI] 和 [BugFix] 两个官方 Tag；FastDeploy 普通 PR 标题规则要求仅保留一个官方 Tag。建议使用更贴合本次测试稳定性变更的标题：

标题建议（可直接复制）：

• [CI] Isolate controller mock to instance level

PR 描述已包含 ## Motivation、## Modifications、## Usage or Command、## Accuracy Tests、## Checklist，结构符合模板。

总体评价

代码改动与 PR 描述一致：实例级 MagicMock 只影响当前 controller，对 __del__ 的调用与异常吞掉路径仍有断言覆盖。未发现需要阻塞合入的代码问题；本地尝试执行 TestDestructor 失败，原因是当前环境缺少 paddle 依赖，未能完成运行时验证。

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (develop@7a60f79). Learn more about missing BASE report.

Additional details and impacted files

@@            Coverage Diff             @@
##             develop    #8092   +/-   ##
==========================================
  Coverage           ?   77.53%           
==========================================
  Files              ?      409           
  Lines              ?    58174           
  Branches           ?     9157           
==========================================
  Hits               ?    45106           
  Misses             ?    10199           
  Partials           ?     2869           

Flag	Coverage Δ
GPU	77.53% <ø> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.