tests/testthat/test-attgtToFetwfeDf.R

In fetwfe: Fused Extended Two-Way Fixed Effects

# Tests for attgtToFetwfeDf()
# Run with: testthat::test_file("tests/testthat/test-attgtToFetwfeDf.R")

library(testthat)

make_simple_df <- function() {
	grid <- expand.grid(
		county = 1:3,
		year = 2000:2002
	)

	transform(
		grid,
		first.treat = ifelse(county == 3, 2001, 0),
		lemp = rnorm(nrow(grid)),
		lpop = rnorm(nrow(grid))
	)
}

test_that("basic happy path works", {
	df <- make_simple_df()
	tidy <- attgtToFetwfeDf(
		data = df,
		yname = "lemp",
		tname = "year",
		idname = "county",
		gname = "first.treat",
		covars = c("lpop")
	)
	expect_s3_class(tidy, "data.frame")
	expect_named(
		tidy,
		c("time_var", "unit_var", "treatment", "response", "lpop")
	)
	expect_true(all(tidy$time_var == as.integer(tidy$time_var)))
	expect_true(all(tidy$treatment %in% 0:1))
	# treated unit 3 should switch on in 2001 and stay on
	unit3 <- subset(tidy, unit_var == "3")
	expect_equal(unit3$treatment, c(0L, 1L, 1L))
})

test_that("duplicate (id,time) rows error", {
	df <- make_simple_df()
	dup <- rbind(df, df[1, ])
	expect_error(
		attgtToFetwfeDf(dup, "lemp", "year", "county", "first.treat"),
		"pair must appear at most once"
	)
})

test_that("non‑constant gname within unit triggers error", {
	df <- make_simple_df()
	df$first.treat[df$county == 2 & df$year == 2002] <- 2002
	expect_error(
		attgtToFetwfeDf(df, "lemp", "year", "county", "first.treat"),
		"irreversible treatment"
	)
})

test_that("dropping first‑period treated units", {
	df <- make_simple_df()
	df$first.treat[df$county == 1] <- 2000 # treated from first period
	tidy <- attgtToFetwfeDf(df, "lemp", "year", "county", "first.treat")
	expect_false(any(tidy$unit_var == "1"))
})

test_that("missing columns are caught", {
	df <- make_simple_df()[, -which(names(make_simple_df()) == "lemp")]
	expect_error(
		attgtToFetwfeDf(df, "lemp", "year", "county", "first.treat"),
		"Column(s) not found",
		fixed = TRUE
	)
})