1.Cook the pasta in a large saucepan of boiling water, uncovered, until just tender; drain. Rinse under cold water; drain.
2.Meanwhile, boil, steam or microwave beans until just tender and bright green; drain. Rinse under cold water; drain.
3.Drain tuna, reserving the oil from one of the cans of tuna. Place tuna in a large bowl; flake with a fork. Add pasta and beans with herbs, capers and rocket; toss gently to combine.
4.Place remaining ingredients and reserved oil in a screw-top jar; shake well. Drizzle dressing over salad; toss gently to combine.
Not suitable to freeze or microwave. This salad, without the dressing, can be made several hours ahead and refrigerated, covered.Note