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In this guide we will see how to configure and use TrustTest with a local LLM using Ollama, without requiring any external API keys.

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Prerequisites

Before starting, make sure you have:
  1. Ollama installed and running locally
  2. A model pulled in Ollama (e.g., gemma3:1b or llama3.2)

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Model Requirements and Hardware Considerations

This example uses two different models:
  • gemma3:1b (1 billion parameters) as the model being evaluated
  • llama3.2 (4 billion parameters) as the judge model for evaluation
With a PC having 8GB of RAM, you should be able to run this example. The smaller gemma3:1b model requires less memory, while the llama3.2 model will be used only for evaluation purposes. Make sure to pull both models in Ollama before running the example: 
ollama pull gemma3:1b
ollama pull llama3.2
Then install the Ollama Python client: 
uv add "trusttest[ollama]"

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Target

The LocalLLMTarget defines the model being evaluated. In this case, it’s the gemma3:1b model: 
import os
from trusttest.targets import Target
import ollama

os.environ["OLLAMA_HOST"] = "http://localhost:11434"

class LocalLLMTarget(Target):
    def __init__(self):
        self.client = ollama.Client(host=os.getenv("OLLAMA_HOST"))

    async def async_respond(self, message: str):
        res = self.client.chat(
            model="gemma3:1b",
            messages=[{"role": "user", "content": message}]
        )
        return res.message.content

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Creating a Test Dataset

You can create a simple test dataset with questions and expected answers: 
from trusttest.dataset_builder import Dataset, DatasetItem
from trusttest.evaluation_contexts import ExpectedResponseContext

dataset = Dataset([
    [
        DatasetItem(
            question="What's the capital of Osona?",
            context=ExpectedResponseContext(
                expected_response="The capital of Osona is Vic.",
                question="What's the capital of Osona?"
            )
        )
    ],
    [
        DatasetItem(
            question="What's the capital of Italy?",
            context=ExpectedResponseContext(
                expected_response="The capital of Italy is Rome.",
                question="What's the capital of Italy?"
            )
        )
    ]
])

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Setting Up Evaluation

Configure your evaluation scenario with the desired evaluators. In this case, we’ll use the CorrectnessEvaluator to evaluate the model’s correctness, and the llama3.2 model as the judge model: 
from trusttest.evaluation_scenarios import EvaluationScenario
from trusttest.evaluator_suite import EvaluatorSuite
from trusttest.evaluators import CorrectnessEvaluator
from trusttest.llm_clients import get_llm_client

llm_judge = get_llm_client(provider="ollama", model="llama3.2")
scenario = EvaluationScenario(
    description="Local LLM model scenario",
    name="Local LLM model scenario",
    evaluator_suite=EvaluatorSuite(
        evaluators=[
            CorrectnessEvaluator(
                llm_client=llm_judge
            )
        ],
        criteria="any_fail"
    )
)

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Running the Evaluation

Finally, run your evaluation: 
from trusttest.probes import DatasetProbe

model_target = LocalLLMTarget()
probe = DatasetProbe(target=target_target, dataset=dataset)
test_set = probe.get_test_set()
results = scenario.evaluate(test_set)

# Display results
results.display()
results.display_summary()

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Complete Example

import os
from typing import Optional

import ollama

from trusttest.dataset_builder import Dataset, DatasetItem
from trusttest.evaluation_contexts import ExpectedResponseContext
from trusttest.evaluation_scenarios import EvaluationScenario
from trusttest.evaluator_suite import EvaluatorSuite
from trusttest.evaluators import CorrectnessEvaluator
from trusttest.llm_clients import get_llm_client
from trusttest.targets import Target
from trusttest.probes import DatasetProbe

os.environ["OLLAMA_HOST"] = "http://localhost:11434"

class LocalLLMTarget(Target):
    def __init__(self):
        self.client = ollama.Client(host=os.getenv("OLLAMA_HOST"))

    async def async_respond(self, message: str) -> Optional[str]:
        res = self.client.chat(
            model="gemma3:1b",
            messages=[{"role": "user", "content": message}]
        )
        return res.message.content

model_target = LocalLLMTarget()

dataset = Dataset([
    [
        DatasetItem(
            question="What's the capital of Osona?",
            context=ExpectedResponseContext(
                expected_response="The capital of Osona is Vic.",
                question="What's the capital of Osona?"
            )
        )
    ],
    [
        DatasetItem(
            question="What's the capital of Italy?",
            context=ExpectedResponseContext(
                expected_response="The capital of Italy is Rome.",
                question="What's the capital of Italy?"
            )
        )
    ]
])

probe = DatasetProbe(target=target_target, dataset=dataset)
scenario = EvaluationScenario(
    description="Local LLM model scenario",
    name="Local LLM model scenario",
    evaluator_suite=EvaluatorSuite(
        evaluators=[
            CorrectnessEvaluator(
                llm_client=get_llm_client(provider="ollama", model="llama3.2")
            )
        ],
        criteria="any_fail"
    )
)

test_set = probe.get_test_set()
results = scenario.evaluate(test_set)

results.display()
results.display_summary()