Update mock for device arrays

shortfin/tests/apps/llm/components/kvcache/trie_attention_cache_test.py

@@ -56,6 +56,17 @@ def __repr__(self):
 def mock_device_array():
     """Create mock device array with proper interface implementation"""
 
+
+    class MockMapping:
+        def __enter__(self):
+            return self
+
+        def __exit__(self, exc_type: object | None, exc_value: object | None, exc_tb: object | None):
+            pass
+
+        def fill(self, value: int):
+            pass
+
     class MockDeviceArray:
         def __init__(self):
             self.shape = None
@@ -67,6 +78,15 @@ def view(self, *args):
         def copy_from(self, src):
             pass
 
+        def copy_to(self, dst):
+            pass
+
+        def for_transfer(self):
+            return MockDeviceArray()
+
+        def map(self, *, read: bool = False, write: bool = False, discard: bool = False):
+            return MockMapping()
+
     return MockDeviceArray()