[Core][Bugfix]Refactor block manager for better testability (#3492)

tests/core/utils.py

@@ -2,7 +2,7 @@ import time
 from typing import Tuple
 
 from vllm import SamplingParams
-from vllm.sequence import Sequence, SequenceGroup
+from vllm.sequence import Logprob, Sequence, SequenceGroup
 
 
 def create_dummy_prompt(
@@ -23,5 +23,42 @@ def create_dummy_prompt(
     return prompt, seq_group
 
 
+def create_seq_group(
+    seq_prompt_lens=1024,
+    seq_output_lens=(128, ),
+    request_id='0',
+    seq_id_start=0,
+) -> SequenceGroup:
+
+    assert len(seq_output_lens) > 0
+
+    prompt_token_ids = [0] * seq_prompt_lens
+
+    seqs = []
+    for seq_id_offset, output_len in enumerate(seq_output_lens):
+        seq = Sequence(
+            seq_id=seq_id_start + seq_id_offset,
+            prompt="",
+            prompt_token_ids=prompt_token_ids,
+            block_size=16,
+        )
+
+        for i in range(output_len):
+            seq.append_token_id(
+                token_id=i,
+                logprobs={i: Logprob(0.0)},
+            )
+        seqs.append(seq)
+
+    seq_group = SequenceGroup(
+        request_id=request_id,
+        seqs=seqs,
+        sampling_params=SamplingParams(),
+        arrival_time=time.time(),
+    )
+
+    return seq_group
+
+
 def round_up_to_next_block(seq_len: int, block_size: int) -> int:
     return (seq_len + block_size - 1) // block_size