Heat olive oil in a large pot over medium heat. Add rhubarb, onion, red bell pepper, and salt; cook and stir until tender, about 5 minutes. Add ground turkey and garlic and cook until turkey starts to brown, about 5 minutes.
Stir chili powder, cocoa powder, white sugar, cumin, cinnamon, allspice, and cayenne pepper into the pot; cook and stir for 3 minutes. Add blacks beans, diced tomatoes, and corn; mix well to combine. Bring chili to a boil, reduce heat and simmer, covered, until thickened and flavors are combined, about 30 minutes. Season with salt and black pepper.
