Cook pasta according to package directions; add the green beans to the pasta during the last 4-5 minutes of cook time. Drain beans and pasta, reserving 1 cup of cooking liquid.

Add a couple of tablespoons of cooking water to the pesto to thin a bit.  Add the pasta and green beans to the pesto and toss to coat. If necessary, add some of the reserved cooking liquid so that the sauce easily coats the pasta. Top with grated cheese and salt. Serve immediately with mango.