@Test
public void testGetRequiredExpressionVariableAsString()
{

    // Mock dependencies.
    Expression expression = mock(Expression.class);
    DelegateExecution execution = mock(DelegateExecution.class);
    when(expression.getValue(execution)).thenReturn(STRING_VALUE);
    // Call the method under test.
    String result = activitiHelper.getRequiredExpressionVariableAsString(expression, execution, VARIABLE_NAME);
    // Validate the result.
    assertEquals(STRING_VALUE, result);
}