starknet_os_flow_tests: add blake count check to new class test (#10647)

Author: meship-starkware

crates/starknet_os_flow_tests/src/tests.rs

@@ -1290,7 +1290,6 @@ async fn test_experimental_libfuncs_contract(#[values(true, false)] use_kzg_da:
     test_output.perform_default_validations();
 
     // Validate poseidon usage.
-    // TODO(Meshi): Add blake opcode validations.
     let poseidons = test_output.get_builtin_usage(&BuiltinName::poseidon);
     if use_kzg_da {
         expect![[r#"
@@ -1304,6 +1303,13 @@ async fn test_experimental_libfuncs_contract(#[values(true, false)] use_kzg_da:
         .assert_debug_eq(&poseidons);
     }
 
+    // Validate blake usage.
+    let blakes = test_output.runner_output.metrics.opcode_instances.blake_opcode_count;
+    expect![[r#"
+        564
+    "#]]
+    .assert_debug_eq(&blakes);
+
     // Hint coverage.
     test_output.expect_hint_coverage(&format!(
         "test_experimental_libfuncs_contract_use_kzg_da_{}",