add3 test with updated .gitignore

.gitignore

@@ -3,3 +3,4 @@
 .httr-oauth
 .quarto
 .DS_Store
+../.idea/

tests/testthat/test-add3.R

@@ -0,0 +1,86 @@
+library(testthat)
+# library(withr)
+
+# Testing setup
+
+setup({
+  cat("Running setup for test\n")
+})
+
+teardown({
+  cat("Cleaning up tests\n")
+})
+
+# test blocks
+test_that("add3 workds correctly", {
+  expect_equal(add3(5, 6, 7), 18)
+  expect_identical(add3(5, 6, 7), 18)
+})
+
+test_that("order invariant", {
+  expect_equal(add3(1, 2, 3), 6)
+  expect_equal(add3(2, 1, 3), 6)
+  expect_equal(add3(3, 1, 2), 6)
+  expect_equal(add3(1, 3, 2), 6)
+  expect_equal(add3(2, 3, 1), 6)
+  expect_equal(add3(3, 2, 1), 6)
+})
+
+test_that("negatives work", {
+  expect_equal(add3(-1, -2, -3), -6)
+  expect_equal(add3(-3, 1, 2), 0)
+})
+
+test_that("zero works", {
+  expect_equal(add3(0, 0, 1), 1)
+  expect_equal(add3(1, 0, 0), 1)
+  expect_equal(add3(1, 0, 0), 1)
+})
+
+test_that("floats work", {
+  expect_equal(add3(1.1, 2.2, 3.3), 6.6, tolerance = 1e-8)
+})
+
+test_that("warning example", {
+  warn_func <- function() {
+    warning("This is a warning")
+  }
+
+  expect_warning(warn_func(), "warning")
+})
+
+test_that("message example", {
+  msg_func <- function() {
+      message("Sample Message")
+  }
+
+  expect_message(msg_func(), "Message")
+})
+
+test_that("NA/NULL", {
+  expect_null(NULL)
+  expect_true(is.na(NA))
+})
+
+test_that("Length check", {
+  expect_length(1:10, 10)
+})
+
+test_that("Set comparisons", {
+  expect_setequal(c(1, 2, 3), c(3, 2, 1))
+})
+
+test_that("Skipping tests", {
+  skip("Test skip demo")
+  expect_true(FALSE)
+})
+
+# Custom expects
+expect_is_one <- function(object) {
+  expect_true(object == 1,
+              info = paste(object, "is not even"))
+}
+
+test_that("Custom expect", {
+  expect_is_one(1)
+})