Fix issue #2402: Handle missing templates gracefully

Co-Authored-By: Joe Moura <joao@crewai.com>

src/crewai/utilities/prompts.py

@@ -54,10 +54,12 @@ class Prompts(BaseModel):
         response_template=None,
     ) -> str:
         """Constructs a prompt string from specified components."""
-        if not system_template and not prompt_template:
+        if not system_template or not prompt_template:
+            # If any of the required templates are missing, fall back to the default format
             prompt_parts = [self.i18n.slice(component) for component in components]
             prompt = "".join(prompt_parts)
         else:
+            # All templates are provided, use them
             prompt_parts = [
                 self.i18n.slice(component)
                 for component in components
@@ -67,8 +69,12 @@ class Prompts(BaseModel):
             prompt = prompt_template.replace(
                 "{{ .Prompt }}", "".join(self.i18n.slice("task"))
             )
-            response = response_template.split("{{ .Response }}")[0]
+            # Handle missing response_template
-            prompt = f"{system}\n{prompt}\n{response}"
+            if response_template:
+                response = response_template.split("{{ .Response }}")[0]
+                prompt = f"{system}\n{prompt}\n{response}"
+            else:
+                prompt = f"{system}\n{prompt}"
 
         prompt = (
             prompt.replace("{goal}", self.agent.goal)

test_fix_2402.py

@@ -0,0 +1,42 @@
+# test_fix_2402.py
+from crewai import Agent, Task, Crew
+
+# Case 1: Only system_template provided
+agent1 = Agent(
+    role="Test Role",
+    goal="Test Goal",
+    backstory="Test Backstory",
+    system_template="You are a test agent...",
+    # prompt_template is intentionally missing
+)
+
+# Case 2: system_template and prompt_template provided, but response_template missing
+agent2 = Agent(
+    role="Test Role",
+    goal="Test Goal",
+    backstory="Test Backstory",
+    system_template="You are a test agent...",
+    prompt_template="This is a test prompt...",
+    # response_template is intentionally missing
+)
+
+# Create tasks and crews
+task1 = Task(description="Test task 1", agent=agent1, expected_output="Test output 1")
+task2 = Task(description="Test task 2", agent=agent2, expected_output="Test output 2")
+
+crew1 = Crew(agents=[agent1], tasks=[task1])
+crew2 = Crew(agents=[agent2], tasks=[task2])
+
+print("Testing agent with only system_template...")
+try:
+    agent1.execute_task(task1)
+    print("Success! No error was raised.")
+except Exception as e:
+    print(f"Error: {e}")
+
+print("\nTesting agent with missing response_template...")
+try:
+    agent2.execute_task(task2)
+    print("Success! No error was raised.")
+except Exception as e:
+    print(f"Error: {e}")

tests/test_templates.py

@@ -0,0 +1,47 @@
+"""Test template handling in Agent creation."""
+
+import pytest
+from crewai import Agent, Task, Crew
+
+
+def test_agent_with_only_system_template():
+    """Test that an agent with only system_template works without errors."""
+    agent = Agent(
+        role="Test Role",
+        goal="Test Goal",
+        backstory="Test Backstory",
+        allow_delegation=False,
+        system_template="You are a test agent...",
+        # prompt_template is intentionally missing
+    )
+    
+    task = Task(description="Test task", agent=agent, expected_output="Test output")
+    
+    # This should not raise an error
+    try:
+        agent.execute_task(task)
+        assert True
+    except AttributeError:
+        pytest.fail("AttributeError was raised with only system_template")
+
+
+def test_agent_with_missing_response_template():
+    """Test that an agent with system_template and prompt_template but no response_template works without errors."""
+    agent = Agent(
+        role="Test Role",
+        goal="Test Goal",
+        backstory="Test Backstory",
+        allow_delegation=False,
+        system_template="You are a test agent...",
+        prompt_template="This is a test prompt...",
+        # response_template is intentionally missing
+    )
+    
+    task = Task(description="Test task", agent=agent, expected_output="Test output")
+    
+    # This should not raise an error
+    try:
+        agent.execute_task(task)
+        assert True
+    except AttributeError:
+        pytest.fail("AttributeError was raised with missing response_template")