## Test difference_smooths()

## load packages
library("testthat")
library("mgcv")
library("gratia")
library("gamm4")

test_that("difference_smooths() works for a gam model", {
    expect_silent(ds <- difference_smooths(su_m_factor_by, smooth = "s(x2)"))
    expect_s3_class(ds, c("difference_smooth", "tbl_df", "tbl", "data.frame"))

    ## plot
    plt <- draw(ds)
    expect_doppelganger("draw difference_smooths gam", plt)
})

test_that("difference_smooths() works for a gam model including group means", {
    expect_silent(ds <- difference_smooths(su_m_factor_by, smooth = "s(x2)",
                                           group_means = TRUE))
    expect_s3_class(ds, c("difference_smooth", "tbl_df", "tbl", "data.frame"))

    ## plot
    plt <- draw(ds)
    expect_doppelganger("draw difference_smooths gam inc grp means", plt)
})

test_that("difference_smooths() works for a gam model fixed scales", {
    expect_silent(ds <- difference_smooths(su_m_factor_by, smooth = "s(x2)"))
    expect_s3_class(ds, c("difference_smooth", "tbl_df", "tbl", "data.frame"))

    ## plot
    plt <- draw(ds, scales = "fixed")
    expect_doppelganger("draw difference_smooths gam fixed scales", plt)
})

test_that("difference_smooths() works for a gam model fixed scales", {
    expect_silent(ds <- difference_smooths(su_m_factor_by, smooth = "s(x2)"))
    expect_s3_class(ds, c("difference_smooth", "tbl_df", "tbl", "data.frame"))

    ## plot
    plt <- draw(ds, ref_line = TRUE)
    expect_doppelganger("draw difference_smooths gam ref line", plt)
})

test_that("difference_smooths() works for a bam model", {
    skip_on_cran()
    expect_silent(ds <- difference_smooths(su_m_factor_by_bam,
                                           smooth = "s(x2)"))
    expect_s3_class(ds, c("difference_smooth", "tbl_df", "tbl", "data.frame"))

    ## plot
    plt <- draw(ds)
    expect_doppelganger("draw difference_smooths bam", plt)
})

test_that("difference_smooths() works for a gamm model", {
    skip_on_cran()
    skip_on_os(c("windows", "mac"))
    expect_silent(ds <- difference_smooths(su_m_factor_by_gamm,
                                           smooth = "s(x2)"))
    expect_s3_class(ds, c("difference_smooth", "tbl_df", "tbl", "data.frame"))

    ## plot
    plt <- draw(ds)
    expect_doppelganger("draw difference_smooths gamm", plt)
})

test_that("difference_smooths() works for a gamm4 model", {
    skip_on_cran()
    skip_on_os(c("windows", "mac"))
    expect_silent(ds <- difference_smooths(su_m_factor_by_gamm4,
                                           smooth = "s(x2)"))
    expect_s3_class(ds, c("difference_smooth", "tbl_df", "tbl", "data.frame"))

    ## plot
    plt <- draw(ds)
    expect_doppelganger("draw difference_smooths gamm4", plt)
})

test_that("difference_smooths() works with user data", {
    df <- with(su_eg4,
               expand_grid(fac = factor(levels(fac), levels = levels(fac)),
                           x2 = seq_min_max(x2, n = 20),
                           x0 = mean(x0)))
    expect_silent(ds <-
      difference_smooths(su_m_factor_by, smooth = "s(x2)", data = df))
    expect_s3_class(ds, c("difference_smooth", "tbl_df", "tbl", "data.frame"))

    ## plot
    plt <- draw(ds)
    #expect_doppelganger("draw difference_smooths gam", plt)
})

test_that("difference_smooths() works for a bivariate gam", {
    skip_on_cran()
    expect_silent(ds <- difference_smooths(su_m_bivar_by_fac,
        smooth = "s(x,z)"))
    expect_s3_class(ds, c("difference_smooth", "tbl_df", "tbl", "data.frame"))

    ## plot
    plt <- draw(ds)
    expect_doppelganger("draw difference_smooths bivariate gam", plt)

    ## plot
    skip_on_os("mac")
    plt <- draw(ds, contour = TRUE)
    expect_doppelganger("draw difference_smooths bivariate gam contours", plt)
})