contracts: expand sector roots test to cover edge cases

host/contracts/manager_test.go

@@ -1078,4 +1078,36 @@ func TestSectorRoots(t *testing.T) {
 			t.Fatalf("expected sector root %v to be %v, got %v", i, roots[i], check[i])
 		}
 	}
+
+	// try random offsets and lengths
+	for i := 0; i < 200; i++ {
+		offset, limit := frand.Intn(len(roots)), frand.Intn(len(roots))
+
+		check, err = c.SectorRoots(rev.Revision.ParentID, limit, offset)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		// handle special case
+		if limit == 0 {
+			limit = len(roots)
+		}
+
+		// handle case where offset+limit > len(roots)
+		n := limit
+		if offset+limit > len(roots) {
+			n = len(roots) - offset
+		}
+
+		if len(check) != n {
+			t.Fatalf("expected %v sector roots, got %v (offset %d, limit %d, len %d)", n, len(check), offset, limit, len(roots))
+		}
+
+		for i := range check {
+			j := offset + i
+			if check[i] != roots[j] {
+				t.Fatalf("expected sector root %v to be %v, got %v", j, roots[j], check[i])
+			}
+		}
+	}
 }