public ExpressionFunction assertFunction(String name, String expression, Model model) {
        assertNotNull("Model is present in config", model);
        ExpressionFunction function = model.function(name);
        assertNotNull("Function '" + name + "' is in " + model, function);
        assertEquals(name, function.getName());
        assertEquals(expression, function.getBody().getRoot().toString());
        return function;
    }
Helper for testing model import and evaluation

@author bratseth
model-evaluation/src/test/java/ai/vespa/models/evaluation/ModelTester.java