Fix MockDSV4ModelRunner missing spec_algorithm

[Jialin]

Motivation

DSpark (#30261) switched DeepseekV4AttnBackend.__init__ from reading
server_args.speculative_algorithm to model_runner.spec_algorithm, which the
attention-unittest mock runner does not define, so every dsv4 backend construction
through the kit crashes with AttributeError: 'MockDSV4ModelRunner' object has no attribute 'spec_algorithm' (e.g. all dsv4_c4_* cases in
test/registered/attention/unittests/dsv4/test_deepseek_v4.py). This breaks CI for
every PR based on current main.

Modifications

Give the mock SpeculativeAlgorithm.NONE, matching the pre-DSpark behavior for
non-spec cases: the old gate was server_args.speculative_algorithm is not None,
which the mock overrides to None, so with NONE the new gate resolves identically
(needs_cpu_seq_lens unset, is_dspark_draft False). One attribute plus its import in
python/sglang/test/kits/attention_unittest/attention_methods/dsv4_attention.py;
is_draft_worker, the other attribute the new code reads, was already defined.

Accuracy Tests

N/A — test-kit-only change; no runtime code touched.

Speed Tests and Profiling

N/A.

Checklist

• Format your code according to the Format code with pre-commit.
• Add unit tests according to the Run and add unit tests. (This PR repairs the existing dsv4 attention unit tests themselves.)
• Update documentation according to Write documentations.
• Provide accuracy and speed benchmark results according to Test the accuracy and Benchmark the speed.
• Follow the SGLang code style guidance.

Review and Merge Process

1. Ping Merge Oncalls to start the process. See the PR Merge Process.
2. Get approvals from CODEOWNERS and other reviewers.
3. Trigger CI tests with comments or contact authorized users to do so.
   • Common commands include /tag-and-rerun-ci, /tag-run-ci-label, /rerun-failed-ci
4. After green CI and required approvals, ask Merge Oncalls or people with Write permission to merge the PR.

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CI States

Latest PR Test (Base): ⏳ Run #29281398333
Latest PR Test (Extra): ❌ Run #29281398028

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[Jialin]

/tag-run-ci-label

[Jialin]

/rerun-test registered/attention/unittests/dsv4/test_deepseek_v4.py

[github-actions]

⛔ /rerun-test is not available for fork PRs unless the commenter has write permission on the repo.

Please ask a maintainer to run this command, or use the normal CI flow.

[Jialin]

/rerun-stage base-b-test-4-gpu-b200

[github-actions]

⚠️ /rerun-stage has been deprecated.

Stage granularity is too coarse — a stage usually doesn't map to one feature, so rerunning a stage re-pays the cost of unrelated tests. If you don't know which exact test files to rerun, you shouldn't be using /rerun-stage or /rerun-test in the first place.

Use one of these instead:

• Selective tests (you know exactly which files to rerun):

  /rerun-test test_foo.py test_bar.py
  

• Rerun only failed jobs:

  /rerun-failed-ci
  

• Full CI rerun (with extra coverage): add the run-ci or run-ci-extra label and push a new commit (or use /tag-and-rerun-ci).

AMD CI: stage-level dispatch is still available via Actions UI → PR Test (AMD) / PR Test ROCm 7.2 (AMD) → Run workflow → pick a stage from the dropdown.

[Jialin]

/tag-and-rerun-ci

[hnyls2002]

/rerun-test test_deepseek_v4.py

[github-actions]

Results for /rerun-test test_deepseek_v4.py:

🚀 4-gpu-b200 (1 test): ✅ View workflow run

cd test/ && python3 registered/attention/unittests/dsv4/test_deepseek_v4.py

🚀 1-gpu-h100 (1 test): ✅ View workflow run

cd test/ && python3 registered/attention/unittests/dsv4/test_deepseek_v4.py