if (.Platform$OS.type != "windows") {
    library(lme4)
    fm1 <- lmer(Reaction ~ Days + (Days|Subject), sleepstudy)
    stopifnot(isREML(fm1),
              isLMM(fm1),
              !isGLMM(fm1),
              !isNLMM(fm1))

    fm1ML <- refitML(fm1)
    stopifnot(!isREML(fm1ML),
              isLMM(fm1ML),
              !isGLMM(fm1ML),
              !isNLMM(fm1ML))

    gm1 <- glmer(cbind(incidence, size - incidence) ~ period + (1 | herd),
                 data = cbpp, family = binomial)
    stopifnot(!isREML(gm1),
              !isLMM(gm1),
              isGLMM(gm1),
              !isNLMM(gm1))

    nm1 <- nlmer(circumference ~ SSlogis(age, Asym, xmid, scal) ~ Asym|Tree,
                 Orange, start = c(Asym = 200, xmid = 725, scal = 350))
    stopifnot(!isREML(nm1),
              !isLMM(nm1),
              !isGLMM(nm1),
              isNLMM(nm1))


} ## skip on windows (for speed)