diff --git a/src/test/java/dev/ai4j/openai4j/chat/ChatCompletionAsyncTest.java b/src/test/java/dev/ai4j/openai4j/chat/ChatCompletionAsyncTest.java
index 20caf75..3d4a516 100644
--- a/src/test/java/dev/ai4j/openai4j/chat/ChatCompletionAsyncTest.java
+++ b/src/test/java/dev/ai4j/openai4j/chat/ChatCompletionAsyncTest.java
@@ -96,7 +96,7 @@ void testCustomizableApi(ChatCompletionModel model) throws Exception {
     void testTools(ChatCompletionModel model) throws Exception {
 
         // given
-        UserMessage userMessage = UserMessage.from("What is the weather in Boston?");
+        UserMessage userMessage = UserMessage.from("What is the weather in Boston in Celsius?");
 
         ChatCompletionRequest request = ChatCompletionRequest.builder()
                 .model(model)
@@ -158,7 +158,7 @@ void testTools(ChatCompletionModel model) throws Exception {
     void testFunctions(ChatCompletionModel model) throws Exception {
 
         // given
-        UserMessage userMessage = UserMessage.from("What is the weather in Boston?");
+        UserMessage userMessage = UserMessage.from("What is the weather in Boston in Celsius?");
 
         ChatCompletionRequest request = ChatCompletionRequest.builder()
                 .model(model)
@@ -214,7 +214,7 @@ void testFunctions(ChatCompletionModel model) throws Exception {
     void testToolChoice(ChatCompletionModel model) throws Exception {
 
         // given
-        UserMessage userMessage = UserMessage.from("What is the weather in Boston?");
+        UserMessage userMessage = UserMessage.from("What is the weather in Boston in Celsius?");
 
         ChatCompletionRequest request = ChatCompletionRequest.builder()
                 .model(model)
@@ -276,7 +276,7 @@ void testToolChoice(ChatCompletionModel model) throws Exception {
     void testFunctionChoice(ChatCompletionModel model) throws Exception {
 
         // given
-        UserMessage userMessage = UserMessage.from("What is the weather in Boston?");
+        UserMessage userMessage = UserMessage.from("What is the weather in Boston in Celsius?");
 
         ChatCompletionRequest request = ChatCompletionRequest.builder()
                 .model(model)
diff --git a/src/test/java/dev/ai4j/openai4j/chat/ChatCompletionStreamingTest.java b/src/test/java/dev/ai4j/openai4j/chat/ChatCompletionStreamingTest.java
index 1aac441..7c29bca 100644
--- a/src/test/java/dev/ai4j/openai4j/chat/ChatCompletionStreamingTest.java
+++ b/src/test/java/dev/ai4j/openai4j/chat/ChatCompletionStreamingTest.java
@@ -150,7 +150,7 @@ void testCustomizableApi(ChatCompletionModel model) throws Exception {
     void testTools(ChatCompletionModel model) throws Exception {
 
         // given
-        UserMessage userMessage = UserMessage.from("What is the weather in Boston?");
+        UserMessage userMessage = UserMessage.from("What is the weather in Boston in Celsius?");
 
         ChatCompletionRequest request = ChatCompletionRequest.builder()
                 .model(model)
@@ -167,7 +167,7 @@ void testTools(ChatCompletionModel model) throws Exception {
         client.chatCompletion(request)
                 .onPartialResponse(partialResponse -> {
                     Delta delta = partialResponse.choices().get(0).delta();
-                    assertThat(delta.content()).isNull();
+                    assertThat(delta.content()).isNullOrEmpty();
                     assertThat(delta.functionCall()).isNull();
 
                     if (delta.toolCalls() != null) {
@@ -265,7 +265,7 @@ void testTools(ChatCompletionModel model) throws Exception {
     void testFunctions(ChatCompletionModel model) throws Exception {
 
         // given
-        UserMessage userMessage = UserMessage.from("What is the weather in Boston?");
+        UserMessage userMessage = UserMessage.from("What is the weather in Boston in Celsius?");
 
         ChatCompletionRequest request = ChatCompletionRequest.builder()
                 .model(model)
@@ -281,7 +281,7 @@ void testFunctions(ChatCompletionModel model) throws Exception {
         client.chatCompletion(request)
                 .onPartialResponse(partialResponse -> {
                     Delta delta = partialResponse.choices().get(0).delta();
-                    assertThat(delta.content()).isNull();
+                    assertThat(delta.content()).isNullOrEmpty();
                     assertThat(delta.toolCalls()).isNull();
 
                     if (delta.functionCall() != null) {
@@ -359,7 +359,7 @@ void testFunctions(ChatCompletionModel model) throws Exception {
     void testToolChoice(ChatCompletionModel model) throws Exception {
 
         // given
-        UserMessage userMessage = UserMessage.from("What is the weather in Boston?");
+        UserMessage userMessage = UserMessage.from("What is the weather in Boston in Celsius?");
 
         ChatCompletionRequest request = ChatCompletionRequest.builder()
                 .model(model)
@@ -474,7 +474,7 @@ void testToolChoice(ChatCompletionModel model) throws Exception {
     void testFunctionChoice(ChatCompletionModel model) throws Exception {
 
         // given
-        UserMessage userMessage = UserMessage.from("What is the weather in Boston?");
+        UserMessage userMessage = UserMessage.from("What is the weather in Boston in Celsius?");
 
         ChatCompletionRequest request = ChatCompletionRequest.builder()
                 .model(model)
diff --git a/src/test/java/dev/ai4j/openai4j/chat/ChatCompletionTest.java b/src/test/java/dev/ai4j/openai4j/chat/ChatCompletionTest.java
index 93ee120..0f2ea28 100644
--- a/src/test/java/dev/ai4j/openai4j/chat/ChatCompletionTest.java
+++ b/src/test/java/dev/ai4j/openai4j/chat/ChatCompletionTest.java
@@ -128,7 +128,7 @@ void testCustomizableApi(ChatCompletionModel model) {
     void testTools(ChatCompletionModel model) {
 
         // given
-        UserMessage userMessage = UserMessage.from("What is the weather in Boston?");
+        UserMessage userMessage = UserMessage.from("What is the weather in Boston in Celsius?");
 
         ChatCompletionRequest request = ChatCompletionRequest.builder()
                 .model(model)
@@ -308,7 +308,7 @@ void testToolWithoutParameters() {
     void testFunctions(ChatCompletionModel model) {
 
         // given
-        UserMessage userMessage = UserMessage.from("What is the weather in Boston?");
+        UserMessage userMessage = UserMessage.from("What is the weather in Boston in Celsius?");
 
         ChatCompletionRequest request = ChatCompletionRequest.builder()
                 .model(model)
@@ -357,7 +357,7 @@ void testFunctions(ChatCompletionModel model) {
     void testToolChoice(ChatCompletionModel model) {
 
         // given
-        UserMessage userMessage = UserMessage.from("What is the weather in Boston?");
+        UserMessage userMessage = UserMessage.from("What is the weather in Boston in Celsius?");
 
         ChatCompletionRequest request = ChatCompletionRequest.builder()
                 .model(model)
@@ -412,7 +412,7 @@ void testToolChoice(ChatCompletionModel model) {
     void testFunctionChoice(ChatCompletionModel model) {
 
         // given
-        UserMessage userMessage = UserMessage.from("What is the weather in Boston?");
+        UserMessage userMessage = UserMessage.from("What is the weather in Boston in Celsius?");
 
         ChatCompletionRequest request = ChatCompletionRequest.builder()
                 .model(model)