test_that("Jevons index formula is correct",{expect_equal(round(jevons(milk,start="2019-12",end="2020-01"),4),1.0202)})
test_that("Fisher index formula is correct",{expect_equal(round(fisher(milk,start="2019-12",end="2020-01"),4),0.9741)})
test_that("Chain Fisher index formula is correct",{expect_equal(round(chfisher(milk,start="2019-12",end="2020-02"),4),1.0077)})
test_that("GEKS index formula is correct",{expect_equal(round(geks(milk,start="2019-12",end="2020-02",window=3),4),1.0108)})