[Rust Frontend][CI] Unblock more end-to-end test cases (#47735)

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
Signed-off-by: Bugen Zhao <i@bugenzhao.com>

Author: BugenZhao

.buildkite/test-amd.yaml

@@ -1977,15 +1977,21 @@ steps:
   - tests/utils.py
   - tests/benchmarks/test_serve_cli.py
   - tests/entrypoints/openai/chat_completion/test_chat_completion.py
+  - tests/entrypoints/openai/chat_completion/test_chat_logit_bias_validation.py
   - tests/entrypoints/openai/completion/test_shutdown.py
+  - tests/entrypoints/openai/test_return_token_ids.py
+  - tests/entrypoints/openai/test_uds.py
   - tests/v1/sample/test_logprobs_e2e.py
   - vllm/platforms/rocm.py
   commands:
   - export VLLM_USE_RUST_FRONTEND=1
   - export VLLM_WORKER_MULTIPROC_METHOD=spawn
   - pytest -v -s benchmarks/test_serve_cli.py -k "not insecure and not (test_bench_serve and not test_bench_serve_chat)"
   - pytest -v -s entrypoints/openai/chat_completion/test_chat_completion.py -k "not test_invalid_json_schema and not test_invalid_regex"
+  - pytest -v -s entrypoints/openai/chat_completion/test_chat_logit_bias_validation.py -k "not multiple"
   - pytest -v -s entrypoints/openai/completion/test_shutdown.py -k "not engine_failure and not test_abort_timeout_exits_quickly"
+  - pytest -v -s entrypoints/openai/test_return_token_ids.py -k "not test_comparison"
+  - pytest -v -s entrypoints/openai/test_uds.py
   - pytest -v -s v1/sample/test_logprobs_e2e.py -k "test_prompt_logprobs_e2e_server"
 
 - label: Rust Frontend Serve Admin Coverage # TBD
@@ -2000,16 +2006,20 @@ steps:
   - vllm/entrypoints/serve/
   - vllm/v1/engine/
   - tests/utils.py
-  - tests/entrypoints/serve/disagg/test_serving_tokens.py
+  - tests/entrypoints/serve/dev/rpc/test_collective_rpc.py
+  - tests/entrypoints/scale_out/token_in_token_out/test_serving_tokens.py
   - tests/entrypoints/serve/instrumentator/test_basic.py
   - tests/entrypoints/serve/instrumentator/test_metrics.py
+  - tests/entrypoints/serve/tokenize/test_tokenization.py
   - vllm/platforms/rocm.py
   commands:
   - export VLLM_USE_RUST_FRONTEND=1
   - export VLLM_WORKER_MULTIPROC_METHOD=spawn
+  - PYTHONPATH=/vllm-workspace pytest -v -s entrypoints/serve/dev/rpc/test_collective_rpc.py
   - pytest -v -s entrypoints/serve/instrumentator/test_basic.py -k "not show_version and not server_load"
-  - pytest -v -s entrypoints/serve/disagg/test_serving_tokens.py -k "not stream and not lora and not test_generate_logprobs and not stop_string_workflow"
+  - pytest -v -s entrypoints/scale_out/token_in_token_out/test_serving_tokens.py -k "not stream and not lora and not test_generate_logprobs and not stop_string_workflow"
   - pytest -v -s entrypoints/serve/instrumentator/test_metrics.py -k "text and not show and not run_batch and not test_metrics_counts and not test_metrics_exist"
+  - pytest -v -s entrypoints/serve/tokenize/test_tokenization.py -k "not tokenizer_info and not test_tokenize_chat"
 
 - label: Rust Frontend Core Correctness # TBD
   timeout_in_minutes: 180

.buildkite/test_areas/rust_frontend.yaml

@@ -15,24 +15,26 @@ steps:
   - tests/utils.py
   - tests/benchmarks/test_serve_cli.py
   - tests/entrypoints/openai/chat_completion/test_chat_completion.py
-  # - tests/entrypoints/openai/chat_completion/test_chat_logit_bias_validation.py
+  - tests/entrypoints/openai/chat_completion/test_chat_logit_bias_validation.py
 
   # - tests/entrypoints/openai/completion/test_prompt_validation.py
   - tests/entrypoints/openai/completion/test_shutdown.py
-  # - tests/entrypoints/openai/test_return_token_ids.py
-  # - tests/entrypoints/openai/test_uds.py
+  - tests/entrypoints/openai/test_return_token_ids.py
+  - tests/entrypoints/openai/test_uds.py
   - tests/v1/sample/test_logprobs_e2e.py
   commands:
   - export VLLM_USE_RUST_FRONTEND=1
   - export VLLM_WORKER_MULTIPROC_METHOD=spawn
   - pytest -v -s benchmarks/test_serve_cli.py -k "not insecure and not (test_bench_serve and not test_bench_serve_chat)"
   - pytest -v -s entrypoints/openai/chat_completion/test_chat_completion.py -k "not test_invalid_json_schema and not test_invalid_regex"
-  # - pytest -v -s entrypoints/openai/chat_completion/test_chat_logit_bias_validation.py -k "not invalid"
+  - pytest -v -s entrypoints/openai/chat_completion/test_chat_logit_bias_validation.py -k "not multiple"
 
   # - pytest -v -s entrypoints/openai/completion/test_prompt_validation.py -k "not prompt_embeds"
   - pytest -v -s entrypoints/openai/completion/test_shutdown.py -k "not engine_failure and not test_abort_timeout_exits_quickly"
-  # - pytest -v -s entrypoints/openai/test_return_token_ids.py
-  # - pytest -v -s entrypoints/openai/test_uds.py
+  # test_comparison streams differently: Rust emits a separate first (prompt_token_ids) chunk and
+  # finish chunk without logprobs, while the test reads `logprobs.tokens` on every chunk.
+  - pytest -v -s entrypoints/openai/test_return_token_ids.py -k "not test_comparison"
+  - pytest -v -s entrypoints/openai/test_uds.py
   - pytest -v -s v1/sample/test_logprobs_e2e.py -k "test_prompt_logprobs_e2e_server"
 
 - label: Rust Frontend Serve/Admin Coverage
@@ -45,19 +47,24 @@ steps:
   - vllm/entrypoints/serve/
   - vllm/v1/engine/
   - tests/utils.py
-  # - tests/entrypoints/serve/dev/rpc/test_collective_rpc.py
+  - tests/entrypoints/serve/dev/rpc/test_collective_rpc.py
   - tests/entrypoints/scale_out/token_in_token_out/test_serving_tokens.py
   - tests/entrypoints/serve/instrumentator/test_basic.py
   - tests/entrypoints/serve/instrumentator/test_metrics.py
   # - tests/entrypoints/serve/dev/test_sleep.py
+  - tests/entrypoints/serve/tokenize/test_tokenization.py
   commands:
   - export VLLM_USE_RUST_FRONTEND=1
   - export VLLM_WORKER_MULTIPROC_METHOD=spawn
-  # - pytest -v -s entrypoints/serve/dev/rpc/test_collective_rpc.py
+  - PYTHONPATH=/vllm-workspace pytest -v -s entrypoints/serve/dev/rpc/test_collective_rpc.py
+  # server_load can be flaky under the Rust frontend; keep it excluded for now.
   - pytest -v -s entrypoints/serve/instrumentator/test_basic.py -k "not show_version and not server_load"
+  # test_generate_logprobs expects Python-style top_logprobs truncation (dedup sampled + cap at max(k, 1)).
   - pytest -v -s entrypoints/scale_out/token_in_token_out/test_serving_tokens.py -k "not stream and not lora and not test_generate_logprobs and not stop_string_workflow"
   - pytest -v -s entrypoints/serve/instrumentator/test_metrics.py -k "text and not show and not run_batch and not test_metrics_counts and not test_metrics_exist"
   # - pytest -v -s entrypoints/serve/dev/test_sleep.py
+  # /tokenizer_info is not implemented in the Rust frontend (the CLI flag is accepted as a no-op).
+  - pytest -v -s entrypoints/serve/tokenize/test_tokenization.py -k "not tokenizer_info and not test_tokenize_chat"
 
 - label: Rust Frontend Core Correctness
   timeout_in_minutes: 30

rust/src/cmd/src/cli/unsupported.rs

@@ -456,13 +456,17 @@ pub struct ServerUnsupportedArgs {
 
     /// Enable the `/tokenizer_info` endpoint. May expose chat
     /// templates and other tokenizer configuration.
+    ///
+    /// Accepted as a no-op: the Rust frontend serves `/tokenize` and
+    /// `/detokenize`, but does not implement `/tokenizer_info` yet.
     #[arg(
         long,
         visible_alias = "no-enable-tokenizer-info-endpoint",
         default_missing_value = "true",
-        num_args = 0..=1
+        num_args = 0..=1,
+        hide = true
     )]
-    pub enable_tokenizer_info_endpoint: Option<Unsupported>,
+    pub enable_tokenizer_info_endpoint: Option<Noop>,
 
     /// If set to True, log model outputs (generations).
     /// Requires `--enable-log-requests`. As with `--enable-log-requests`,

rust/src/server/src/routes/inference/generate/types.rs

@@ -29,7 +29,9 @@ pub struct GenerateRequest {
 impl Normalizable for GenerateRequest {}
 
 /// Mirrors the Python vLLM `GenerateResponseChoice` class.
-#[serde_with::skip_serializing_none]
+///
+/// Do not skip serializing `None` fields here: non-streaming response types
+/// should serialize `None` as explicit `null`.
 #[derive(Debug, Clone, Serialize)]
 pub(super) struct GenerateResponseChoice {
     pub index: u32,
@@ -58,7 +60,6 @@ pub(super) struct GenerateStreamResponse {
 }
 
 /// Mirrors the Python vLLM `GenerateResponse` class.
-#[serde_with::skip_serializing_none]
 #[derive(Debug, Clone, Serialize)]
 pub(super) struct GenerateResponse {
     pub request_id: String,
@@ -68,7 +69,6 @@ pub(super) struct GenerateResponse {
 }
 
 /// Mirrors the Python vLLM `Logprob` class used in prompt-logprobs payloads.
-#[serde_with::skip_serializing_none]
 #[derive(Debug, Clone, Serialize)]
 pub(super) struct GenerateLogprob {
     pub logprob: f32,

rust/src/server/src/routes/openai/chat_completions.rs

@@ -211,7 +211,7 @@ async fn collect_chat_completion(
                     Some(prefix) => Some(format!("{prefix}{}", message.text())),
                     None => Some(message.text()).filter(|t| !t.is_empty()),
                 },
-                tool_calls: Some(tool_calls).filter(|calls| !calls.is_empty()),
+                tool_calls,
                 reasoning: if include_reasoning { reasoning } else { None },
             },
             logprobs,

rust/src/server/src/routes/openai/chat_completions/convert.rs

@@ -830,7 +830,7 @@ mod tests {
         let message = ChatCompletionMessage {
             role: AssistantRole,
             content: Some("answer".to_string()),
-            tool_calls: None,
+            tool_calls: Vec::new(),
             reasoning: Some("inner".to_string()),
         };
         let message_json = serde_json::to_value(message).expect("message serializes");

rust/src/server/src/routes/openai/chat_completions/types.rs

@@ -331,7 +331,9 @@ impl Normalizable for ChatCompletionRequest {
 }
 
 /// Mirrors the Python vLLM `ChatCompletionResponse` class.
-#[serde_with::skip_serializing_none]
+///
+/// Do not skip serializing `None` fields here: non-streaming response types
+/// should serialize `None` as explicit `null`.
 #[derive(Debug, Clone, Serialize)]
 pub(super) struct ChatCompletionResponse {
     pub id: String,
@@ -347,7 +349,6 @@ pub(super) struct ChatCompletionResponse {
 }
 
 /// Mirrors the Python vLLM `ChatCompletionResponseChoice` class.
-#[serde_with::skip_serializing_none]
 #[derive(Debug, Clone, Serialize)]
 pub(super) struct ChatCompletionChoice {
     pub index: u32,
@@ -370,12 +371,12 @@ impl fmt::Display for AssistantRole {
 }
 
 /// Mirrors the Python vLLM response `ChatMessage` class.
-#[serde_with::skip_serializing_none]
 #[derive(Debug, Clone, Serialize)]
 pub(super) struct ChatCompletionMessage {
     pub role: AssistantRole,
     pub content: Option<String>,
-    pub tool_calls: Option<Vec<ToolCall>>,
+    #[serde(skip_serializing_if = "Vec::is_empty")]
+    pub tool_calls: Vec<ToolCall>,
     pub reasoning: Option<String>,
 }
 

rust/src/server/src/routes/openai/completions/types.rs

@@ -196,7 +196,9 @@ impl Normalizable for CompletionRequest {
 }
 
 /// Mirrors the Python vLLM `CompletionResponse` class.
-#[serde_with::skip_serializing_none]
+///
+/// Do not skip serializing `None` fields here: non-streaming response types
+/// should serialize `None` as explicit `null`.
 #[derive(Debug, Clone, Serialize)]
 pub(super) struct CompletionResponse {
     pub id: String,
@@ -210,7 +212,6 @@ pub(super) struct CompletionResponse {
 }
 
 /// Mirrors the Python vLLM `CompletionResponseChoice` class.
-#[serde_with::skip_serializing_none]
 #[derive(Debug, Clone, Serialize)]
 pub(super) struct CompletionChoice {
     pub index: u32,

rust/src/server/src/routes/openai/utils/types.rs

@@ -311,7 +311,9 @@ pub enum MessageContent {
 // ============================================================================
 
 /// Mirrors the Python vLLM `UsageInfo` class.
-#[serde_with::skip_serializing_none]
+///
+/// Do not skip serializing `None` fields here: non-streaming response types
+/// should serialize `None` as explicit `null`.
 #[derive(Debug, Clone, Serialize)]
 pub struct Usage {
     pub prompt_tokens: usize,
@@ -402,14 +404,12 @@ pub struct LogProbs {
 }
 
 /// Mirrors the Python vLLM `ChatCompletionLogProbs` class.
-#[serde_with::skip_serializing_none]
 #[derive(Debug, Clone, Serialize)]
 pub struct ChatLogProbs {
     pub content: Option<Vec<ChatLogProbsContent>>,
 }
 
 /// Mirrors the Python vLLM `ChatCompletionLogProbsContent` class.
-#[serde_with::skip_serializing_none]
 #[derive(Debug, Clone, Serialize)]
 pub struct ChatLogProbsContent {
     pub token: String,
@@ -419,7 +419,6 @@ pub struct ChatLogProbsContent {
 }
 
 /// Mirrors the Python vLLM `ChatCompletionLogProb` class.
-#[serde_with::skip_serializing_none]
 #[derive(Debug, Clone, Serialize)]
 pub struct TopLogProb {
     pub token: String,
@@ -436,7 +435,6 @@ pub struct ErrorResponse {
     pub error: ErrorDetail,
 }
 
-#[serde_with::skip_serializing_none]
 #[derive(Debug, Clone, Deserialize, Serialize)]
 pub struct ErrorDetail {
     pub message: String,

rust/src/server/src/routes/tests.rs

@@ -2191,6 +2191,28 @@ async fn non_stream_chat_returns_json_response() {
     assert_eq!(json["usage"]["prompt_tokens"], 22);
     assert_eq!(json["usage"]["completion_tokens"], 3);
     assert_eq!(json["usage"]["total_tokens"], 25);
+
+    // Unset optional fields are serialized as explicit `null` on
+    // non-streaming responses...
+    let response_object = json.as_object().expect("response object");
+    let choice = json["choices"][0].as_object().expect("choice object");
+    let message = choice["message"].as_object().expect("message object");
+    for (object, key) in [
+        (response_object, "system_fingerprint"),
+        (response_object, "prompt_token_ids"),
+        (response_object, "kv_transfer_params"),
+        (choice, "logprobs"),
+        (choice, "stop_reason"),
+        (choice, "token_ids"),
+        (message, "reasoning"),
+    ] {
+        assert!(
+            object.contains_key(key) && object[key].is_null(),
+            "expected explicit null `{key}`: {json}"
+        );
+    }
+    // ...except `tool_calls`, which Python pops from the payload when empty.
+    assert!(!message.contains_key("tool_calls"), "{json}");
 }
 
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
@@ -2956,6 +2978,25 @@ async fn non_stream_completions_return_json_response() {
     assert_eq!(json["choices"][0]["text"], "hi");
     assert_eq!(json["choices"][0]["finish_reason"], "stop");
     assert_eq!(json["usage"]["completion_tokens"], 3);
+
+    // Unset optional fields are serialized as explicit `null` on
+    // non-streaming responses.
+    let response_object = json.as_object().expect("response object");
+    let choice = json["choices"][0].as_object().expect("choice object");
+    for (object, key) in [
+        (response_object, "system_fingerprint"),
+        (response_object, "kv_transfer_params"),
+        (choice, "logprobs"),
+        (choice, "stop_reason"),
+        (choice, "prompt_logprobs"),
+        (choice, "token_ids"),
+        (choice, "prompt_token_ids"),
+    ] {
+        assert!(
+            object.contains_key(key) && object[key].is_null(),
+            "expected explicit null `{key}`: {json}"
+        );
+    }
 }
 
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
@@ -4371,10 +4412,10 @@ async fn include_reasoning_false_suppresses_reasoning_in_non_stream_chat() {
     let json: serde_json::Value = serde_json::from_str(&text).expect("decode json");
 
     assert_eq!(json["choices"][0]["message"]["content"], "answer");
+    // Suppressed fields are serialized as explicit `null` on non-streaming
+    // responses.
     assert!(
-        json["choices"][0]["message"]
-            .as_object()
-            .is_some_and(|message| !message.contains_key("reasoning")),
+        json["choices"][0]["message"]["reasoning"].is_null(),
         "{text}"
     );
 }
@@ -4476,14 +4517,14 @@ async fn include_reasoning_false_suppresses_non_stream_output_metadata() {
     let choice = json["choices"][0].as_object().expect("choice object");
 
     assert_eq!(json["choices"][0]["message"]["content"], "answer");
+    // Suppressed fields are serialized as explicit `null` on non-streaming
+    // responses.
     assert!(
-        json["choices"][0]["message"]
-            .as_object()
-            .is_some_and(|message| !message.contains_key("reasoning")),
+        json["choices"][0]["message"]["reasoning"].is_null(),
         "{text}"
     );
-    assert!(!choice.contains_key("logprobs"), "{text}");
-    assert!(!choice.contains_key("token_ids"), "{text}");
+    assert!(choice["logprobs"].is_null(), "{text}");
+    assert!(choice["token_ids"].is_null(), "{text}");
     assert!(json["prompt_token_ids"].is_array(), "{text}");
 }