GH-4586 Fixed some merge exceptions in DeepSeekStreamFunctionCallingHelper

models/spring-ai-deepseek/src/main/java/org/springframework/ai/deepseek/api/DeepSeekStreamFunctionCallingHelper.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 the original author or authors.
+ * Copyright 2023-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -34,6 +34,7 @@
  * ChatCompletionChunk in case of function calling message.
  *
  * @author Geng Rong
+ * @author Sun Yuhan
  */
 public class DeepSeekStreamFunctionCallingHelper {
 
@@ -76,22 +77,23 @@ private ChunkChoice merge(ChunkChoice previous, ChunkChoice current) {
 	}
 
 	private ChatCompletionMessage merge(ChatCompletionMessage previous, ChatCompletionMessage current) {
-		String content = (current.content() != null ? current.content()
-				: "" + ((previous.content() != null) ? previous.content() : ""));
+		String content = (current.content() != null
+				? (previous.content() != null ? previous.content() + current.content() : current.content())
+				: (previous.content() != null ? previous.content() : ""));
 		Role role = (current.role() != null ? current.role() : previous.role());
 		role = (role != null ? role : Role.ASSISTANT); // default to ASSISTANT (if null
 		String name = (current.name() != null ? current.name() : previous.name());
 		String toolCallId = (current.toolCallId() != null ? current.toolCallId() : previous.toolCallId());
 
 		List<ToolCall> toolCalls = new ArrayList<>();
 		ToolCall lastPreviousTooCall = null;
-		if (previous.toolCalls() != null) {
+		if (!CollectionUtils.isEmpty(previous.toolCalls())) {
 			lastPreviousTooCall = previous.toolCalls().get(previous.toolCalls().size() - 1);
 			if (previous.toolCalls().size() > 1) {
 				toolCalls.addAll(previous.toolCalls().subList(0, previous.toolCalls().size() - 1));
 			}
 		}
-		if (current.toolCalls() != null) {
+		if (!CollectionUtils.isEmpty(current.toolCalls())) {
 			if (current.toolCalls().size() > 1) {
 				throw new IllegalStateException("Currently only one tool call is supported per message!");
 			}

models/spring-ai-deepseek/src/test/java/org/springframework/ai/deepseek/api/DeepSeekStreamFunctionCallingHelperTest.java

@@ -0,0 +1,214 @@
+/*
+ * Copyright 2025-2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.ai.deepseek.api;
+
+import java.util.List;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.ai.deepseek.api.DeepSeekApi.ChatCompletionChunk;
+import org.springframework.ai.deepseek.api.DeepSeekApi.ChatCompletionMessage;
+import org.springframework.ai.deepseek.api.DeepSeekApi.ChatCompletionMessage.ChatCompletionFunction;
+import org.springframework.ai.deepseek.api.DeepSeekApi.ChatCompletionMessage.Role;
+import org.springframework.ai.deepseek.api.DeepSeekApi.ChatCompletionMessage.ToolCall;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Unit test for {@link DeepSeekStreamFunctionCallingHelper}.
+ *
+ * @author Sun Yuhan
+ */
+class DeepSeekStreamFunctionCallingHelperTest {
+
+	private DeepSeekStreamFunctionCallingHelper helper;
+
+	@BeforeEach
+	void setUp() {
+		this.helper = new DeepSeekStreamFunctionCallingHelper();
+	}
+
+	@Test
+	void mergeWhenPreviousIsNullShouldReturnCurrent() {
+		// Given
+		ChatCompletionChunk current = new ChatCompletionChunk("id1", List.of(), 123L, "model1", null, null, null, null);
+
+		// When
+		ChatCompletionChunk result = this.helper.merge(null, current);
+
+		// Then
+		assertThat(result).isEqualTo(current);
+	}
+
+	@Test
+	void mergeShouldMergeBasicFieldsFromCurrentAndPrevious() {
+		// Given
+		ChatCompletionChunk previous = new ChatCompletionChunk("id1", List.of(), 123L, "model1", null, null, null,
+				null);
+		ChatCompletionChunk current = new ChatCompletionChunk("id2", List.of(), null, null, null, null, null, null);
+
+		// When
+		ChatCompletionChunk result = this.helper.merge(previous, current);
+
+		// Then
+		assertThat(result.id()).isEqualTo("id2"); // from current
+		assertThat(result.created()).isEqualTo(123L); // from previous
+		assertThat(result.model()).isEqualTo("model1"); // from previous
+	}
+
+	@Test
+	void mergeShouldMergeMessagesContent() {
+		// Given
+		ChatCompletionMessage previousMsg = new ChatCompletionMessage("Hello ", Role.ASSISTANT, null, null, null);
+		ChatCompletionMessage currentMsg = new ChatCompletionMessage("World!", Role.ASSISTANT, null, null, null);
+
+		ChatCompletionChunk previous = new ChatCompletionChunk("id",
+				List.of(new ChatCompletionChunk.ChunkChoice(null, 0, previousMsg, null)), 123L, "model", null, null,
+				null, null);
+
+		ChatCompletionChunk current = new ChatCompletionChunk("id",
+				List.of(new ChatCompletionChunk.ChunkChoice(null, 0, currentMsg, null)), 123L, "model", null, null,
+				null, null);
+
+		// When
+		ChatCompletionChunk result = this.helper.merge(previous, current);
+
+		// Then
+		assertThat(result.choices().get(0).delta().content()).isEqualTo("Hello World!");
+	}
+
+	@Test
+	void mergeShouldHandleToolCallsMerging() {
+		// Given
+		ChatCompletionFunction func1 = new ChatCompletionFunction("func1", "{\"arg1\":");
+		ToolCall toolCall1 = new ToolCall("call_123", "function", func1);
+		ChatCompletionMessage previousMsg = new ChatCompletionMessage(null, Role.ASSISTANT, null, null,
+				List.of(toolCall1));
+
+		ChatCompletionFunction func2 = new ChatCompletionFunction("func1", "\"value1\"}");
+		ToolCall toolCall2 = new ToolCall(null, "function", func2); // No ID -
+																	// continuation
+		ChatCompletionMessage currentMsg = new ChatCompletionMessage(null, Role.ASSISTANT, null, null,
+				List.of(toolCall2));
+
+		ChatCompletionChunk previous = new ChatCompletionChunk("id",
+				List.of(new ChatCompletionChunk.ChunkChoice(null, 0, previousMsg, null)), 123L, "model", null, null,
+				null, null);
+
+		ChatCompletionChunk current = new ChatCompletionChunk("id",
+				List.of(new ChatCompletionChunk.ChunkChoice(null, 0, currentMsg, null)), 123L, "model", null, null,
+				null, null);
+
+		// When
+		ChatCompletionChunk result = this.helper.merge(previous, current);
+
+		// Then
+		assertThat(result.choices()).hasSize(1);
+		assertThat(result.choices().get(0).delta().toolCalls()).hasSize(1);
+		ToolCall mergedToolCall = result.choices().get(0).delta().toolCalls().get(0);
+		assertThat(mergedToolCall.id()).isEqualTo("call_123");
+		assertThat(mergedToolCall.function().name()).isEqualTo("func1");
+		assertThat(mergedToolCall.function().arguments()).isEqualTo("{\"arg1\":\"value1\"}");
+	}
+
+	@Test
+	void mergeWithSingleToolCallShouldWork() {
+		// Given
+		ToolCall toolCall = new ToolCall("call_1", "function", new ChatCompletionFunction("func1", "{}"));
+		ChatCompletionMessage msg = new ChatCompletionMessage(null, Role.ASSISTANT, null, null, List.of(toolCall));
+
+		ChatCompletionChunk previous = new ChatCompletionChunk("id", List.of(), 123L, "model", null, null, null, null);
+		ChatCompletionChunk current = new ChatCompletionChunk("id",
+				List.of(new ChatCompletionChunk.ChunkChoice(null, 0, msg, null)), 123L, "model", null, null, null,
+				null);
+
+		// When
+		ChatCompletionChunk result = this.helper.merge(previous, current);
+
+		// Then
+		assertThat(result).isNotNull();
+		assertThat(result.choices().get(0).delta().toolCalls()).hasSize(1);
+	}
+
+	@Test
+	void isStreamingToolFunctionCallWhenNullChunkShouldReturnFalse() {
+		// When & Then
+		assertThat(this.helper.isStreamingToolFunctionCall(null)).isFalse();
+	}
+
+	@Test
+	void isStreamingToolFunctionCallWhenEmptyChoicesShouldReturnFalse() {
+		// Given
+		ChatCompletionChunk chunk = new ChatCompletionChunk("id", List.of(), 123L, "model", null, null, null, null);
+
+		// When & Then
+		assertThat(this.helper.isStreamingToolFunctionCall(chunk)).isFalse();
+	}
+
+	@Test
+	void isStreamingToolFunctionCallWhenHasToolCallsShouldReturnTrue() {
+		// Given
+		ToolCall toolCall = new ToolCall("call_1", "function", new ChatCompletionFunction("func", "{}"));
+		ChatCompletionMessage msg = new ChatCompletionMessage(null, Role.ASSISTANT, null, null, List.of(toolCall));
+		ChatCompletionChunk chunk = new ChatCompletionChunk("id",
+				List.of(new ChatCompletionChunk.ChunkChoice(null, 0, msg, null)), 123L, "model", null, null, null,
+				null);
+
+		// When & Then
+		assertThat(this.helper.isStreamingToolFunctionCall(chunk)).isTrue();
+	}
+
+	@Test
+	void isStreamingToolFunctionCallFinishWhenFinishReasonIsToolCallsShouldReturnTrue() {
+		// Given
+		ChatCompletionMessage msg = new ChatCompletionMessage(null, Role.ASSISTANT, null, null, null);
+		ChatCompletionChunk.ChunkChoice choice = new ChatCompletionChunk.ChunkChoice(
+				DeepSeekApi.ChatCompletionFinishReason.TOOL_CALLS, 0, msg, null);
+		ChatCompletionChunk chunk = new ChatCompletionChunk("id", List.of(choice), 123L, "model", null, null, null,
+				null);
+
+		// When & Then
+		assertThat(this.helper.isStreamingToolFunctionCallFinish(chunk)).isTrue();
+	}
+
+	@Test
+	void mergeWhenCurrentToolCallsIsEmptyListShouldNotThrowException() {
+		// Given
+		ToolCall toolCall = new ToolCall("call_1", "function", new ChatCompletionFunction("func1", "{}"));
+		ChatCompletionMessage previousMsg = new ChatCompletionMessage(null, Role.ASSISTANT, null, null,
+				List.of(toolCall));
+
+		// Empty list instead of null
+		ChatCompletionMessage currentMsg = new ChatCompletionMessage(null, Role.ASSISTANT, null, null, List.of());
+
+		ChatCompletionChunk previous = new ChatCompletionChunk("id",
+				List.of(new ChatCompletionChunk.ChunkChoice(null, 0, previousMsg, null)), 123L, "model", null, null,
+				null, null);
+
+		ChatCompletionChunk current = new ChatCompletionChunk("id",
+				List.of(new ChatCompletionChunk.ChunkChoice(null, 0, currentMsg, null)), 123L, "model", null, null,
+				null, null);
+
+		// When
+		ChatCompletionChunk result = this.helper.merge(previous, current);
+
+		// Then
+		assertThat(result).isNotNull();
+	}
+
+}