library(glmmTMB)
if (requireNamespace("pbkrtest") && requireNamespace("lme4")) {
    fm1_lmer <- lme4::lmer(formula(fm1), lme4::sleepstudy)
    fm2_lmer <- lme4::lmer(formula(fm2), lme4::sleepstudy)

    fm1 <- update(fm1, REML = TRUE)
    fm2 <- update(fm2, REML = TRUE)
    
    pbkrtest_dof <- function(m) {
        vva <- pbkrtest::vcovAdj(m)
        vv0 <- vcov(m)
        p <- length(fixef(m))
        Lmat <- diag(p)
        ddf <- apply(Lmat, 1, \(L) pbkrtest::ddf_Lb(vva, L, vv0))
        return(ddf)
    }

    test_that("approx KR df match with pbkrtest (fm1)", {
        df1 <- pbkrtest_dof(fm1_lmer)
        df2 <- dof_KR(fm1)
        expect_equal(df1, unname(c(df2)), tolerance = 1e-6)
    })

    test_that("approx KR df match with pbkrtest (fm2)", {
        df1 <- pbkrtest_dof(fm2_lmer)
        df2 <- dof_KR(fm2)
        expect_equal(df1, unname(c(df2)), tolerance = 1e-6)
    })

    test_that("KR in summary", {
        expect_identical(
            coef(summary(fm1, ddf = "kenward-roger"))$cond[,"ddf"],
            c(dof_KR(fm1))
        )
    })
}


test_that("Satt in summary", {
        expect_identical(
            unname(coef(summary(fm1, ddf = "satterthwaite"))$cond[,"ddf"]),
            c(dof_satt(fm1))
        )
    })               

## add lmerTest comparisons?
## emmeans