core[patch]: update dict prompt template (#30967)

Align with JS changes made in
https://github.com/langchain-ai/langchainjs/pull/8043

libs/core/tests/unit_tests/prompts/__snapshots__/test_chat.ambr

@@ -3135,6 +3135,27 @@
                 'name': 'PromptTemplate',
                 'type': 'constructor',
               }),
+              dict({
+                'id': list([
+                  'langchain_core',
+                  'prompts',
+                  'dict',
+                  'DictPromptTemplate',
+                ]),
+                'kwargs': dict({
+                  'template': dict({
+                    'cache_control': dict({
+                      'type': '{foo}',
+                    }),
+                    'text': "What's in this image?",
+                    'type': 'text',
+                  }),
+                  'template_format': 'f-string',
+                }),
+                'lc': 1,
+                'name': 'DictPromptTemplate',
+                'type': 'constructor',
+              }),
               dict({
                 'id': list([
                   'langchain',

libs/core/tests/unit_tests/prompts/test_chat.py

@@ -973,6 +973,11 @@ def test_chat_tmpl_serdes(snapshot: SnapshotAssertion) -> None:
                         "hello",
                         {"text": "What's in this image?"},
                         {"type": "text", "text": "What's in this image?"},
+                        {
+                            "type": "text",
+                            "text": "What's in this image?",
+                            "cache_control": {"type": "{foo}"},
+                        },
                         {
                             "type": "image_url",
                             "image_url": "data:image/jpeg;base64,{my_image}",
@@ -1012,7 +1017,7 @@ def test_chat_tmpl_serdes(snapshot: SnapshotAssertion) -> None:
 @pytest.mark.xfail(
     reason=(
         "In a breaking release, we can update `_convert_to_message_template` to use "
-        "_DictMessagePromptTemplate for all `dict` inputs, allowing for templatization "
+        "DictPromptTemplate for all `dict` inputs, allowing for templatization "
         "of message attributes outside content blocks. That would enable the below "
         "test to pass."
     )

libs/core/tests/unit_tests/prompts/test_dict.py

@@ -0,0 +1,34 @@
+from langchain_core.load import load
+from langchain_core.prompts.dict import DictPromptTemplate
+
+
+def test__dict_message_prompt_template_fstring() -> None:
+    template = {
+        "type": "text",
+        "text": "{text1}",
+        "cache_control": {"type": "{cache_type}"},
+    }
+    prompt = DictPromptTemplate(template=template, template_format="f-string")
+    expected = {
+        "type": "text",
+        "text": "important message",
+        "cache_control": {"type": "ephemeral"},
+    }
+    actual = prompt.format(text1="important message", cache_type="ephemeral")
+    assert actual == expected
+
+
+def test_deserialize_legacy() -> None:
+    ser = {
+        "type": "constructor",
+        "lc": 1,
+        "id": ["langchain_core", "prompts", "message", "_DictMessagePromptTemplate"],
+        "kwargs": {
+            "template_format": "f-string",
+            "template": {"type": "audio", "audio": "{audio_data}"},
+        },
+    }
+    expected = DictPromptTemplate(
+        template={"type": "audio", "audio": "{audio_data}"}, template_format="f-string"
+    )
+    assert load(ser) == expected

libs/core/tests/unit_tests/prompts/test_imports.py

@@ -6,6 +6,7 @@ EXPECTED_ALL = [
     "BasePromptTemplate",
     "ChatMessagePromptTemplate",
     "ChatPromptTemplate",
+    "DictPromptTemplate",
     "FewShotPromptTemplate",
     "FewShotPromptWithTemplates",
     "FewShotChatMessagePromptTemplate",

libs/core/tests/unit_tests/prompts/test_message.py

@@ -1,61 +0,0 @@
-from pathlib import Path
-
-from langchain_core.messages import AIMessage, BaseMessage, ToolMessage
-from langchain_core.prompts.message import _DictMessagePromptTemplate
-
-CUR_DIR = Path(__file__).parent.absolute().resolve()
-
-
-def test__dict_message_prompt_template_fstring() -> None:
-    template = {
-        "role": "assistant",
-        "content": [
-            {"type": "text", "text": "{text1}", "cache_control": {"type": "ephemeral"}},
-        ],
-        "name": "{name1}",
-        "tool_calls": [
-            {
-                "name": "{tool_name1}",
-                "args": {"arg1": "{tool_arg1}"},
-                "id": "1",
-                "type": "tool_call",
-            }
-        ],
-    }
-    prompt = _DictMessagePromptTemplate(template=template, template_format="f-string")
-    expected: BaseMessage = AIMessage(
-        [
-            {
-                "type": "text",
-                "text": "important message",
-                "cache_control": {"type": "ephemeral"},
-            },
-        ],
-        name="foo",
-        tool_calls=[
-            {
-                "name": "do_stuff",
-                "args": {"arg1": "important arg1"},
-                "id": "1",
-                "type": "tool_call",
-            }
-        ],
-    )
-    actual = prompt.format_messages(
-        text1="important message",
-        name1="foo",
-        tool_arg1="important arg1",
-        tool_name1="do_stuff",
-    )[0]
-    assert actual == expected
-
-    template = {
-        "role": "tool",
-        "content": "{content1}",
-        "tool_call_id": "1",
-        "name": "{name1}",
-    }
-    prompt = _DictMessagePromptTemplate(template=template, template_format="f-string")
-    expected = ToolMessage("foo", name="bar", tool_call_id="1")
-    actual = prompt.format_messages(content1="foo", name1="bar")[0]
-    assert actual == expected