## 'check_along_is_time' ------------------------------------------------------

test_that("'check_along_is_time' returns true with valid model object", {
    set.seed(0)
    data <- expand.grid(age = 0:9, sex = c("F", "M"), time = 2001:2005)
    data$popn <- rpois(n = nrow(data), lambda = 100)
    data$deaths <- rpois(n = nrow(data), lambda = 10)
    formula <- deaths ~ (age + sex + time)^2
    mod <- mod_pois(formula = formula,
                    data = data,
                    exposure = popn)
    expect_true(check_along_is_time(mod))
    mod <- set_prior(mod, age:time ~ N())
    expect_true(check_along_is_time(mod))    
})

test_that("'check_along_is_time' returns true when there is no time variable", {
    set.seed(0)
    data <- expand.grid(age = 0:9, sex = c("F", "M"))
    data$popn <- rpois(n = nrow(data), lambda = 100)
    data$deaths <- rpois(n = nrow(data), lambda = 10)
    formula <- deaths ~ (age + sex)^2
    mod <- mod_pois(formula = formula,
                    data = data,
                    exposure = popn)
    mod <- set_prior(mod, age:sex ~ RW(along = "age"))
    expect_true(check_along_is_time(mod))
})

test_that("'check_bage_mod' returns expected error message with invalid model object", {
    set.seed(0)
    data <- expand.grid(age = 0:9, sex = c("F", "M"), time = 2001:2005)
    data$popn <- rpois(n = nrow(data), lambda = 100)
    data$deaths <- rpois(n = nrow(data), lambda = 10)
    formula <- deaths ~ (age + sex + time)^2
    mod <- mod_pois(formula = formula,
                    data = data,
                    exposure = popn)
    mod <- set_prior(mod, age:time ~ RW(along = "age", s = 0.5))
    expect_error(check_along_is_time(mod),
                 "Unable to forecast term \"age:time\".")
})


## 'check_bage_mod' -----------------------------------------------------------

test_that("'check_bage_mod' returns true with valid model object", {
    set.seed(0)
    data <- expand.grid(age = 0:9, sex = c("F", "M"))
    data$popn <- rpois(n = nrow(data), lambda = 100)
    data$deaths <- rpois(n = nrow(data), lambda = 10)
    formula <- deaths ~ age + sex
    mod <- mod_pois(formula = formula,
                    data = data,
                    exposure = popn)
    expect_true(check_bage_mod(mod))
})

test_that("'check_bage_mod' returns expected error message with invalid model object", {
    expect_error(check_bage_mod(x = NULL, nm_x = "model"),
                 "`model` does not have class")
})


## 'check_flag' ---------------------------------------------------------------

test_that("'check_flag' returns TRUE with valid inputs", {
    x <- TRUE
    expect_true(check_flag(x, nm_x = "x"))
    x <- FALSE
    expect_true(check_flag(x))
})

test_that("'check_flag' throws expected error non-length-1", {
    y <- logical()
    expect_error(check_flag(y, nm_x = "z"),
                 "`z` does not have length 1")
    z <- c(TRUE, TRUE)
    expect_error(check_flag(z, nm_x = "z"),
                 "`z` does not have length 1")
})

test_that("'check_flag' throws expected error non-logical", {
    x <- "hello"
    expect_error(check_flag(x, nm_x = "x"),
                 "`x` does not have class <logical>")
})

test_that("'check_flag' throws expected error NA", {
    x <- NA
    expect_error(check_flag(x, nm_x = "xx"),
                 "`xx` is NA")
})


## 'check_format_prior_formula' -----------------------------------------------

test_that("'check_format_prior_formula' returns TRUE with valid inputs", {
    expect_true(check_format_prior_formula(age ~ N()))
    expect_true(check_format_prior_formula(time:sex~RW()))
})

test_that("'check_format_prior_formula' returns correct error with invalid inputs", {
    expect_error(check_format_prior_formula(N()),
                 "`formula` not a formula.")
    expect_error(check_format_prior_formula("age~N()"),
                 "`formula` not a formula.")
    expect_error(check_format_prior_formula(~N()),
                 "`formula` has too few elements")
})


## 'check_formula_has_intercept' ----------------------------------------------

test_that("'check_formula_has_intercept' returns TRUE with valid inputs", {
    expect_true(check_formula_has_intercept(y ~ x + z))
    expect_true(check_formula_has_intercept(y ~ 1))
})

test_that("'check_formula_has_intercept' returns correct error with invalid inputs", {
    expect_error(check_formula_has_intercept(y ~ age - 1),
                 "`formula` does not include an intercept.")
})


## 'check_formula_has_response' -----------------------------------------------

test_that("'check_formula_has_response' returns TRUE with valid inputs", {
    expect_true(check_formula_has_response(y ~ x + z))
    expect_true(check_formula_has_response(y ~ x + z - 1))
    expect_true(check_formula_has_response(y ~ 1))
})

test_that("'check_formula_has_response' returns correct error with invalid inputs", {
    expect_error(check_formula_has_response(~ x + z),
                 "`formula` does not include a response variable.")
    expect_error(check_formula_has_response(~ 1),
                 "`formula` does not include a response variable.")
})


## 'check_formula_has_variable' -----------------------------------------------

test_that("'check_formula_has_variable' returns TRUE with valid inputs", {
    expect_true(check_formula_has_variable(name = "age",
                                           formula = deaths ~ age*sex + time))
    expect_true(check_formula_has_variable(name = "age",
                                           formula = deaths ~ age:sex + time))
    expect_true(check_formula_has_variable(name = "time",
                                           formula = deaths ~ age*sex + time))
})

test_that("'check_formula_has_variable' returns correct error with invalid inputs", {
    expect_error(check_formula_has_variable(name = "wrong",
                                            formula = deaths ~ age*sex + time),
                 "`formula` does not have variable \"wrong\"")
})


## 'check_formula_vnames_in_data' ---------------------------------------------

test_that("'check_formula_vnames_in_data' returns TRUE with valid inputs", {
    expect_true(check_formula_vnames_in_data(y ~ x + z,
                                             data.frame(x = 1, y = 2, z = 3)))
    expect_true(check_formula_vnames_in_data(y ~ x + z - 1,
                                             data.frame(x = 1, y = 2, z = 3)))
    expect_true(check_formula_vnames_in_data(y ~ 1,
                                             data.frame(x = 1, y = 2, z = 3)))
})

test_that("'check_formula_vnames_in_data' returns correct error with invalid inputs", {
    expect_error(check_formula_vnames_in_data(y ~ wrong,
                                              data.frame(x = 1, y = 2, z = 3)),
                 "Variable `wrong` from `formula` not found in `data`.")
})


## 'check_has_disp_if_condition_on_expected' ----------------------------------

test_that("'check_has_disp_if_condition_on_expected' works", {
    set.seed(0)
    data <- expand.grid(age = 0:9, sex = c("F", "M"))
    data$popn <- rpois(n = nrow(data), lambda = 100)
    data$deaths <- rpois(n = nrow(data), lambda = 10)
    formula <- deaths ~ age + sex
    mod <- mod_pois(formula = formula,
                    data = data,
                    exposure = popn)
    expect_true(check_has_disp_if_condition_on_expected(mod))
    mod <- set_disp(mod, mean = 0)
    expect_error(check_has_disp_if_condition_on_expected(mod),
                 "`condition_on` is \"expected\" but model has no dispersion term")
})


## 'check_is_dataframe' -------------------------------------------------------

test_that("'check_is_dataframe' works with valid inputs", {
  expect_true(check_is_dataframe(x = data.frame(), nm_x = "data"))
  expect_true(check_is_dataframe(x = tibble(), nm_x = data))
})

test_that("'check_is_dataframe' throws correct error with non-dataframe", {
  expect_error(check_is_dataframe(x = "a", nm_x = "val"),
               "`val` is not a data frame.")
})
          

## 'check_is_fitted' ----------------------------------------------------------

test_that("'check_is_fitted' works", {
    set.seed(0)
    data <- expand.grid(age = 0:9, sex = c("F", "M"))
    data$popn <- rpois(n = nrow(data), lambda = 100)
    data$deaths <- rpois(n = nrow(data), lambda = 10)
    formula <- deaths ~ age + sex
    mod <- mod_pois(formula = formula,
                    data = data,
                    exposure = popn)
    expect_error(check_is_fitted(x = mod, nm_x = "Y"),
                 "`Y` has not been fitted.")
    mod <- fit(mod)
    expect_true(check_is_fitted(x = mod, nm_x = "Y"))
})


## 'check_is_formula' ---------------------------------------------------------

test_that("'check_is_formula' returns TRUE when 'formula' is a formula", {
    expect_true(check_is_formula(deaths ~ age + sex))
    expect_true(check_is_formula(~ age))
})

test_that("'check_is_formula' throws correct error when not formula", {
    expect_error(check_is_formula("~age"),
                 "`formula` is not an R formula.")
})


## 'check_is_matrix' ----------------------------------------------------------

test_that("'check_is_matrix' works with valid inputs", {
  expect_true(check_is_matrix(x = matrix(), nm_x = "data"))
})

test_that("'check_is_matrix' throws correct error with non-matrix", {
  expect_error(check_is_matrix(x = "a", nm_x = "val"),
               "`val` is not a matrix.")
})


## 'check_is_ssvd' ------------------------------------------------------

test_that("'check_is_ssvd' works with valid inputs", {
  expect_true(check_is_ssvd(x = HMD, nm_x = "ssvd"))
  expect_error(check_is_ssvd(x = NULL, nm_x = "ssvd"),
               "`ssvd` does not hold scaled SVD values.")
})


## 'check_length_along_ge' ----------------------------------------------------

test_that("'check_length_along_ge' returns TRUE with valid inputs", {
  expect_true(check_length_along_ge(length_along = 10L,
                                    min = 3L,
                                    nm = "age:sex",
                                    prior = Lin()))
})

test_that("'check_length_along_ge' throws correct error with length less than min", {
  expect_error(check_length_along_ge(length_along = 1L,
                                     min = 2L,
                                     nm = "age:sex",
                                     prior = Lin()),
               "`Lin\\(\\)` prior cannot be used for `age:sex` term.")                
})


## 'check_length_effect_ge' ------------------------------------------------------

test_that("'check_length_effect_ge' returns TRUE with valid inputs", {
    expect_true(check_length_effect_ge(length_effect = 10L,
                                       min = 3L,
                                       nm = "age",
                                       prior = N()))
})

test_that("'check_length_effect_ge' throws correct error with length less than min", {
    expect_error(check_length_effect_ge(length_effect = 1L,
                                        min = 2L,
                                        nm = "age",
                                        prior = N()),
                 "`N\\(\\)` prior cannot be used for `age` term.")                
})


## 'check_mod_est_sim_compatible' ---------------------------------------------

test_that("'check_mod_est_sim_compatible' returns TRUE with indentical models", {
    set.seed(0)
    data <- expand.grid(age = 0:9, time = 2000:2005, sex = c("F", "M"))
    data$popn <- rpois(n = nrow(data), lambda = 100)
    data$deaths <- rpois(n = nrow(data), lambda = 10)
    formula <- deaths ~ age + sex + time
    mod <- mod_pois(formula = formula,
                    data = data,
                    exposure = popn)
    expect_true(check_mod_est_sim_compatible(mod, mod))
})

test_that("'check_mod_est_sim_compatible' raises correct error with different classes", {
    set.seed(0)
    data <- expand.grid(age = 0:9, time = 2000:2005, sex = c("F", "M"))
    data$popn <- rpois(n = nrow(data), lambda = 100)
    data$deaths <- rpois(n = nrow(data), lambda = 10)
    formula <- deaths ~ age + sex + time
    mod <- mod_pois(formula = formula,
                    data = data,
                    exposure = popn)
    expect_error(check_mod_est_sim_compatible(mod, 1L),
                 "`mod_est` and `mod_sim` have different classes")
})

test_that("'check_mod_est_sim_compatible' raises correct error with different outcomes", {
    set.seed(0)
    data <- expand.grid(age = 0:9, time = 2000:2005, sex = c("F", "M"))
    data$popn <- rpois(n = nrow(data), lambda = 100)
    data$deaths1 <- rpois(n = nrow(data), lambda = 10)
    data$deaths2 <- rpois(n = nrow(data), lambda = 10)
    formula1 <- deaths1 ~ age + sex + time
    formula2 <- deaths2 ~ age + sex + time
    mod1 <- mod_pois(formula = formula1,
                    data = data,
                    exposure = popn)
    mod2 <- mod_pois(formula = formula2,
                    data = data,
                    exposure = popn)
    expect_error(check_mod_est_sim_compatible(mod1, mod2),
                 "`mod_est` and `mod_sim` have different outcome variables")
})

test_that("'check_mod_est_sim_compatible' raises correct error when data have different variables", {
    set.seed(0)
    data <- expand.grid(age = 0:9, time = 2000:2005, sex = c("F", "M"))
    data$popn <- rpois(n = nrow(data), lambda = 100)
    data$deaths <- rpois(n = nrow(data), lambda = 10)
    data2 <- data
    data2$region <- "a"
    formula <- deaths ~ age + sex + time
    mod1 <- mod_pois(formula = formula,
                    data = data,
                    exposure = popn)
    mod2 <- mod_pois(formula = formula,
                    data = data2,
                    exposure = popn)
    expect_error(check_mod_est_sim_compatible(mod1, mod2),
                 "`mod_est` and `mod_sim` have different variables.")
})

test_that("'check_mod_est_sim_compatible' raises correct error when data have different values", {
    set.seed(0)
    data <- expand.grid(age = 0:9, time = 2000:2005, sex = c("F", "M"))
    data$popn <- rpois(n = nrow(data), lambda = 100)
    data$deaths <- rpois(n = nrow(data), lambda = 10)
    data2 <- data
    data2$time[118] <- 2004
    formula <- deaths ~ age + sex + time
    mod1 <- mod_pois(formula = formula,
                    data = data,
                    exposure = popn)
    mod2 <- mod_pois(formula = formula,
                    data = data2,
                    exposure = popn)
    expect_error(check_mod_est_sim_compatible(mod1, mod2),
                 "`mod_est` and `mod_sim` have different data")
})


## 'check_min_max_ar' --------------------------------------------------------------

test_that("'check_min_max_ar' returns TRUE with valid inputs", {
    expect_true(check_min_max_ar(min = -1, max = 1))
    expect_true(check_min_max_ar(min = 0, max = 0.9))
})

test_that("'check_min_max_ar' returns correct error with non-numeric", {
    expect_error(check_min_max_ar(min = "-1", max = 1),
                 "`min` is non-numeric.")
})

test_that("'check_min_max_ar' returns correct error with wrong length", {
    expect_error(check_min_max_ar(min = -1, max = 1:2),
                 "`max` does not have length 1.")
})

test_that("'check_min_max_ar' returns correct error with NA", {
    expect_error(check_min_max_ar(min = NA_real_, max = 1),
                 "`min` is NA.")
})

test_that("'check_min_max_ar' returns correct error with min < -1", {
    expect_error(check_min_max_ar(min = -1.00001, max = 1),
                 "`min` is less than -1.")
})

test_that("'check_min_max_ar' returns correct error with max < 1.0001", {
    expect_error(check_min_max_ar(min = -1, max = 1.00001),
                 "`max` is greater than 1.")
})

test_that("'check_min_max_ar' returns correct error with max <= min", {
    expect_error(check_min_max_ar(min = 0, max = 0),
                 "`max` is less than or equal to `min`.")
})


## 'check_n' ------------------------------------------------------------------

test_that("'check_n' returns TRUE with valid inputs", {
    expect_true(check_n(n = 4, nm_n = "n", min = 4L, max = NULL, null_ok = FALSE))
    expect_true(check_n(n = NULL, nm_n = "n", min = 4L, max = NULL, null_ok = TRUE))
})

test_that("'check_n' throws correct error with non-numeric", {
    expect_error(check_n(n = "4", nm_n = "n", min = 4L, max = NULL, null_ok = FALSE),
                 "`n` is non-numeric")
})

test_that("'check_n' throws correct error with wrong length", {
    expect_error(check_n(n = integer(), nm_n = "n", min = 4L, max = NULL, null_ok = FALSE),
                 "`n` does not have length 1")
    expect_error(check_n(n = 10:11, nm_n = "n", min = 4L, max = NULL, null_ok = FALSE),
                 "`n` does not have length 1")
})

test_that("'check_n' throws correct error with NA", {
    expect_error(check_n(n = NA_real_, nm_n = "n", min = 4L, max = NULL, null_ok = FALSE),
                 "`n` is NA")
})

test_that("'check_n' throws correct error with Inf", {
    expect_error(check_n(n = Inf, nm_n = "n", min = 4L, max = NULL, null_ok = FALSE),
                 "`n` is Inf")
})

test_that("'check_n' throws correct error with non-integer", {
    expect_error(check_n(n = 6.4, nm_n = "n", min = 4L, max = NULL, null_ok = FALSE),
                 "`n` is not an integer")
})

test_that("'check_n' throws correct error when less than min", {
    expect_error(check_n(n = 3, nm_n = "n", min = 4L, max = NULL, null_ok = FALSE),
                 "`n` is less than 4")
})

test_that("'check_n' throws correct error when greater than max", {
    expect_error(check_n(n = 60, nm_n = "n", min = 4, max = 10, null_ok = FALSE),
                 "`n` is greater than 10")
})


## 'check_numeric' ------------------------------------------------------------------

test_that("'check_numeric' returns TRUE with valid inputs", {
    expect_true(check_numeric(x = 1:4, nm_x = "x"))
    expect_true(check_numeric(x = c(-1, 0), nm_x = "x"))
})

test_that("'check_numeric' throws correct error with non-numeric", {
    expect_error(check_numeric(x = "4", nm_x = "x"),
                 "`x` is non-numeric")
})

test_that("'check_numeric' throws correct error with 0 length", {
    expect_error(check_numeric(x = integer(), nm_x = "x"), 
                 "`x` has length 0")
})

test_that("'check_numeric' throws correct error with NA", {
    expect_error(check_numeric(x = c(1, NA), nm_x = "x"),
                 "`x` has NA")
})

test_that("'check_numeric' throws correct error with Inf", {
    expect_error(check_numeric(x = c(100, -1, Inf), nm_x = "x"),
                 "`x` has non-finite value.")
})


## 'check_offset_in_data' -----------------------------------------------------

test_that("'check_offset_in_data' returns TRUE with valid formula", {
    expect_true(check_offset_in_data(vname_offset = "~popn + deaths",
                                     nm_offset = "exposure",
                                     data = data.frame(deaths = 1, popn = 2)))
})

test_that("'check_offset_in_data' throws correct error with invalid formula", {
  expect_error(check_offset_in_data(vname_offset = "~popn + wrong",
                                    nm_offset = "exposure",
                                    data = data.frame(deaths = 1, popn = 2)),
               "Problem with formula used for `exposure`.")
})

test_that("'check_offset_in_data' returns TRUE with valid name", {
    expect_true(check_offset_in_data(vname_offset = "popn",
                                     nm_offset = "exposure",
                                     data = data.frame(deaths = 1, popn = 2)))
})

test_that("'check_offset_in_data' returns correct error with invalid name - exposure", {
    expect_error(check_offset_in_data(vname_offset = "popn",
                                      nm_offset = "exposure",
                                      data = data.frame(deaths = 1, wrong = 2)),
                 "`exposure` not found in `data`")
})

test_that("'check_offset_in_data' returns correct error with invalid name - size", {
    expect_error(check_offset_in_data(vname_offset = "popn",
                                      nm_offset = "size",
                                      data = data.frame(deaths = 1, wrong = 2)),
                 "`size` not found in `data`")
})

## 'check_offset_nonneg' ----------------------------------------------------

test_that("'check_offset_nonneg' returns TRUE with valid inputs - formula", {
    expect_true(check_offset_nonneg(vname_offset = "~popn - deaths",
                                    nm_offset = "exposure",
                                    data = data.frame(sex = 1:2,
                                                      popn = c(0, 1.1),
                                                      deaths = 0:1)))
})

test_that("'check_offset_nonneg' returns TRUE with valid inputs - name", {
    expect_true(check_offset_nonneg(vname_offset = "popn",
                                    nm_offset = "exposure",
                                    data = data.frame(sex = 1:2,
                                                      popn = c(0, 1.1),
                                                      deaths = 0:1)))
})

test_that("'check_offset_nonneg' returns correct error with invalid inputs - formula", {
  expect_error(check_offset_nonneg(vname_offset = "~popn - 1",
                                   nm_offset = "exposure",
                                   data = data.frame(sex = 1:2,
                                                     popn = c(-1, 1),
                                                     deaths = 0:1)),
               "`exposure` has negative value.")
})

test_that("'check_offset_nonneg' returns correct error with invalid inputs - name", {
    expect_error(check_offset_nonneg(vname_offset = "popn",
                                    nm_offset = "exposure",
                                    data = data.frame(sex = 1:3,
                                                      popn = c(-1, 1, -3),
                                                      deaths = 0:2)),
                 "`exposure` has negative values.")
})


## 'check_offset_not_in_formula' ----------------------------------------------

test_that("'check_offset_not_in_formula' returns TRUE with valid inputs - formula", {
    expect_true(check_offset_not_in_formula(vname_offset = "~popn^2 + log(popn) + deaths",
                                            nm_offset = "exposure",
                                            formula = deaths ~ age + time))
})

test_that("'check_offset_not_in_formula' returns TRUE with valid inputs - name", {
    expect_true(check_offset_not_in_formula(vname_offset = "popn",
                                            nm_offset = "exposure",
                                            formula = deaths ~ age + time))
})

test_that("'check_offset_not_in_formula' returns correct error with invalid inputs - name", {
    expect_error(check_offset_not_in_formula(vname_offset = "popn",
                                             nm_offset = "exposure",
                                             formula = popn ~ age + time),
                 "`exposure` included in `formula`.")
})


## 'check_resp_le_offset' -----------------------------------------------------

test_that("'check_resp_le_offset' returns TRUE with valid inputs - formula", {
  data <- data.frame(deaths = c(0, 1, NA, 0,  NA),
                     sex = rep("F", 5),
                     popn =   c(0, 1, 2,  NA, NA))
  expect_true(check_resp_le_offset(formula = deaths ~ sex,
                                   vname_offset = "~  popn",
                                   nm_offset = "size",
                                   data = data))
})

test_that("'check_resp_le_offset' returns TRUE with valid inputs - name", {
  data <- data.frame(deaths = c(0, 1, NA, 0,  NA),
                     sex = rep("F", 5),
                     popn =   c(0, 1, 2,  NA, NA))
  expect_true(check_resp_le_offset(formula = deaths ~ sex,
                                   vname_offset = "popn",
                                   nm_offset = "size",
                                   data = data))
})

test_that("'check_resp_le_offset' raises correct error with invalid inputs - formula", {
    data <- data.frame(deaths = c(0, 1, NA, 0,  2),
                       sex = rep("F", 5),
                       popn =   c(0, 1, 2,  NA, 1))
    expect_error(check_resp_le_offset(formula = deaths ~ sex,
                                      vname_offset = "~popn - 0.1",
                                      nm_offset = "size",
                                      data = data),
                 "Response greater than `size`.")
})

test_that("'check_resp_le_offset' raises correct error with invalid inputs - formula", {
    data <- data.frame(deaths = c(0, 1, NA, 0,  2),
                       sex = rep("F", 5),
                       popn =   c(0, 1, 2,  NA, 1))
    expect_error(check_resp_le_offset(formula = deaths ~ sex,
                                      vname_offset = "popn",
                                      nm_offset = "size",
                                      data = data),
                 "Response greater than `size`.")
})


## 'check_resp_zero_if_offset_zero' -------------------------------------------

test_that("'check_resp_zero_if_offset_zero' returns TRUE with valid inputs - formula", {
    data <- data.frame(deaths = c(0, 1, NA, 0,  NA),
                       sex = rep("F", 5),
                       popn =   c(0, 1, 2,  NA, NA))
    expect_true(check_resp_zero_if_offset_zero(formula = deaths ~ sex,
                                               vname_offset = "~popn^2",
                                               nm_offset = "exposure",
                                               data = data))
})

test_that("'check_resp_zero_if_offset_zero' returns TRUE with valid inputs - name", {
    data <- data.frame(deaths = c(0, 1, NA, 0,  NA),
                       sex = rep("F", 5),
                       popn =   c(0, 1, 2,  NA, NA))
    expect_true(check_resp_zero_if_offset_zero(formula = deaths ~ sex,
                                               vname_offset = "popn",
                                               nm_offset = "exposure",
                                               data = data))
})

test_that("'check_resp_zero_if_offset_zero' raises correct error with invalid inputs - formula", {
  data <- data.frame(deaths = c(0, 1, NA, 0,  1),
                     sex = rep("F", 5),
                     popn =   c(0, 1, 2,  NA, 0))
  expect_error(check_resp_zero_if_offset_zero(formula = deaths ~ sex,
                                              vname_offset = "~popn^2",
                                              nm_offset = "exposure",
                                              data = data),
               "Response is non-zero but `exposure` is zero.")
})

test_that("'check_resp_zero_if_offset_zero' raises correct error with invalid inputs - name", {
  data <- data.frame(deaths = c(0, 1, NA, 0,  1),
                     sex = rep("F", 5),
                     popn =   c(0, 1, 2,  NA, 0))
  expect_error(check_resp_zero_if_offset_zero(formula = deaths ~ sex,
                                              vname_offset = "popn",
                                              nm_offset = "exposure",
                                              data = data),
               "Response is non-zero but `exposure` is zero.")
})


## 'check_response_nonneg' ----------------------------------------------------

test_that("'check_response_nonneg' returns TRUE with valid inputs", {
    expect_true(check_response_nonneg(formula = deaths ~ sex,
                                      data = data.frame(sex = 1:2, deaths = 0:1),
                                      nm_distn = "pois"))
})

test_that("'check_response_nonneg' returns correct error with invalid inputs", {
    expect_error(check_response_nonneg(formula = deaths ~ sex,
                                       data.frame(sex = 1:2, deaths = c(-1, 1)),
                                       nm_distn = "Poisson"),
                 "Model uses Poisson distribution but response variable has negative value.")
    expect_error(check_response_nonneg(formula = deaths ~ sex,
                                       data.frame(sex = 1:2, deaths = c(-1, -2)),
                                       nm_distn = "Poisson"),
                 "Model uses Poisson distribution but response variable has negative values.")
})


## 'check_scale' --------------------------------------------------------------

test_that("'check_scale' returns TRUE with valid inputs", {
    expect_true(check_scale(1L, nm_x = "x", zero_ok = FALSE))
    expect_true(check_scale(0.001, nm_x = "x", zero_ok = FALSE))
})

test_that("'check_scale' returns correct error with non-numeric", {
    expect_error(check_scale("1", nm_x = "x", zero_ok = FALSE),
                 "`x` is non-numeric.")
})

test_that("'check_scale' returns correct error with non-numeric", {
    expect_error(check_scale("1", nm_x = "x", zero_ok = FALSE),
                 "`x` is non-numeric.")
})

test_that("'check_scale' returns correct error with wrong length", {
    expect_error(check_scale(1:2, nm_x = "x", zero_ok = FALSE),
                 "`x` does not have length 1.")
})

test_that("'check_scale' returns correct error with NA", {
    expect_error(check_scale(NA_real_, nm_x = "x", zero_ok = FALSE),
                 "`x` is NA.")
})

test_that("'check_scale' returns correct error with Inf", {
    expect_error(check_scale(Inf, nm_x = "x", zero_ok = FALSE),
                 "`x` is infinite.")
})

test_that("'check_scale' returns correct error with negative", {
    expect_true(check_scale(0, nm_x = "x", zero_ok = TRUE))
    expect_error(check_scale(-1, nm_x = "x", zero_ok = TRUE),
                 "`x` is negative.")
})

test_that("'check_scale' returns correct error with non-positive", {
    expect_error(check_scale(0, nm_x = "x", zero_ok = FALSE),
                 "`x` is non-positive.")
    expect_error(check_scale(-1, nm_x = "x", zero_ok = FALSE),
                 "`x` is non-positive.")
})


## 'check_string' --------------------------------------------------------------

test_that("'check_string' returns TRUE with valid inputs", {
    expect_true(check_string("age", nm_x = "x"))
})

test_that("'check_string' returns correct error with non-numeric", {
    expect_error(check_string(1, nm_x = "x"),
                 "`x` is non-character.")
})

test_that("'check_string' returns correct error with wrong length", {
    expect_error(check_string(c("a", "b"), nm_x = "x"),
                 "`x` does not have length 1.")
})

test_that("'check_string' returns correct error with NA", {
    expect_error(check_string(NA_character_, nm_x = "x"),
                 "`x` is NA.")
})

test_that("'check_string' returns correct error with blank", {
    expect_error(check_string("", nm_x = "x"),
                 "`x` is blank.")
})


## 'check_ssvd_has_sexgender' -------------------------------------------------

test_that("'check_ssvd_has_sexgender' works", {
  expect_true(check_ssvd_has_sexgender(x = HMD, nm_x = "ssvd"))
  HMD_nogender <- HMD
  HMD_nogender$data <- HMD_nogender$data[sapply(HMD_nogender$data$labels_sexgender, is.null),]
  expect_error(check_ssvd_has_sexgender(x = HMD_nogender, nm_x = "ssvd"),
               "`ssvd` does not have a sex/gender dimension.")
})


## 'check_svd_agesex' ---------------------------------------------------------

test_that("'check_svd_agesex' works with bage_prior_svd, correct inputs", {
  prior <- SVD(HMD)
  expect_true(check_svd_agesex(prior = prior,
                               var_age = "age",
                               nm = "age:sex",
                               agesex = "age:sex"))
})

test_that("'check_svd_agesex'  throws correct error when 'var_age' is NULL", {
  prior <- SVD_AR1(HMD)
  expect_error(check_svd_agesex(prior = prior,
                                nm = "bla",
                                var_age = NULL,
                                agesex = "other"),
               "Problem with `SVD_AR1\\(\\)` prior for term `bla`.")
})

test_that("'check_svd_agesex'  throws correct error when agesex is 'other'", {
  prior <- SVD_RW(HMD)
  expect_error(check_svd_agesex(prior = prior,
                                nm = "bla",
                                var_age = "age",
                                agesex = "other"),
               "Problem with `SVD_RW\\(\\)` prior for term `bla`.")
})


## 'check_svd_time' ---------------------------------------------------------

test_that("'check_svd_time' works with bage_prior_svd_ar, correct inputs", {
  prior <- SVD_AR1(HMD)
  expect_true(check_svd_time(prior = prior,
                             nm = "age:year:gender",
                             var_time = "year"))
})

test_that("'check_svd_time'  throws correct error when time variable not identified", {
  prior <- SVD_RW(HMD)
  expect_error(check_svd_time(prior = prior,
                                nm = "reg:age:time",
                                var_time = NULL),
               "Problem with `SVD_RW\\(\\)` prior for term `reg:age:time`.")
})

test_that("'check_svd_time'  throws correct error when time variable not identified", {
  prior <- SVD_RW2(HMD)
  expect_error(check_svd_time(prior = prior,
                              nm = "reg:age:sex",
                              var_time = "time"),
               "Problem with `SVD_RW2\\(\\)` prior for term `reg:age:sex`.")
})


## 'check_widths' -------------------------------------------------------------

test_that("'check_widths' returns TRUE with valid inputs", {
    expect_true(check_widths(0.96))
    expect_true(check_widths(c(0.2, 0.8)))
    expect_true(check_widths(c(0.001, 1)))
})

test_that("'check_widths' throws expected error non-numeric", {
    expect_error(check_widths(TRUE),
                 "`widths` has class <logical>.")
})

test_that("'check_widths' throws expected error length 0", {
    expect_error(check_widths(integer()),
                 "`widths` has length 0.")
})

test_that("'check_widths' throws expected error NA", {
    expect_error(check_widths(c(NA, 1)),
                 "`widths` has NA.")
    expect_error(check_widths(c(NA, 1, NA)),
                 "`widths` has NAs.")
})

test_that("'check_widths' throws expected error too low", {
    expect_error(check_widths(0),
                 "`widths` has value not in interval \\(0, 1\\].")
})

test_that("'check_widths' throws expected error too high", {
    expect_error(check_widths(c(1.2, 1.3)),
                 "`widths` has values not in interval \\(0, 1\\].")
})