integration test

Author: liangel-02

tests/integration_tests/features.py

@@ -346,6 +346,18 @@ def build_features_test_list() -> list[OverrideDefinitions]:
             "fsdp+flex_attn+per_op_sac",
             ngpu=4,
         ),
+        OverrideDefinitions(
+            [
+                [
+                    "--parallelism.data_parallel_shard_degree=4",
+                    "--activation_checkpoint.mode='full'",
+                    "--model.flavor=debugmodel_varlen_attn",
+                ]
+            ],
+            "FSDP+VARLEN_ATTN",
+            "fsdp+varlen_attn",
+            ngpu=4,
+        ),
         OverrideDefinitions(
             [
                 [