1 files changed, 80 insertions, 0 deletions
diff --git a/test/gleam/map_test.gleam b/test/gleam/map_test.gleam
index 34f3ee6..cd669f9 100644
--- a/test/gleam/map_test.gleam
+++ b/test/gleam/map_test.gleam
@@ -204,3 +204,83 @@ pub fn fold_test() {
   |> map.fold(0, add)
   |> should.equal(0)
 }
+
+fn range(start, end, a) {
+  case end - start {
+    n if n < 1 -> a
+    _ -> range(start, end - 1, [end - 1, ..a])
+  }
+}
+
+fn list_to_map(list) {
+  list
+  |> list.map(fn(n) { #(n, n) })
+  |> map.from_list
+}
+
+fn grow_and_shrink_map(initial_size, final_size) {
+  range(0, initial_size, [])
+  |> list_to_map
+  |> list.fold(
+    range(final_size, initial_size, []),
+    _,
+    fn(map, item) { map.delete(map, item) },
+  )
+}
+
+// maps should be equal even if the insert/removal order was different
+pub fn insert_order_equality_test() {
+  grow_and_shrink_map(8, 2)
+  |> should.equal(grow_and_shrink_map(4, 2))
+  grow_and_shrink_map(17, 10)
+  |> should.equal(grow_and_shrink_map(12, 10))
+  grow_and_shrink_map(2000, 1000)
+  |> should.equal(grow_and_shrink_map(1000, 1000))
+}
+
+// ensure operations on a map don't mutate it
+pub fn persistence_test() {
+  let a = list_to_map([0])
+  map.insert(a, 0, 5)
+  map.insert(a, 1, 6)
+  map.delete(a, 0)
+  map.get(a, 0)
+  |> should.equal(Ok(0))
+}
+
+// using maps as keys should work (tests hash function)
+pub fn map_as_key_test() {
+  let l = range(0, 1000, [])
+  let a = list_to_map(l)
+  let a2 = list_to_map(list.reverse(l))
+  let a3 = grow_and_shrink_map(2000, 1000)
+  let b = grow_and_shrink_map(60, 50)
+  let c = grow_and_shrink_map(50, 20)
+  let d = grow_and_shrink_map(2, 2)
+
+  let map1 =
+    map.new()
+    |> map.insert(a, "a")
+    |> map.insert(b, "b")
+    |> map.insert(c, "c")
+    |> map.insert(d, "d")
+
+  map.get(map1, a)
+  |> should.equal(Ok("a"))
+  map.get(map1, a2)
+  |> should.equal(Ok("a"))
+  map.get(map1, a3)
+  |> should.equal(Ok("a"))
+  map.get(map1, b)
+  |> should.equal(Ok("b"))
+  map.get(map1, c)
+  |> should.equal(Ok("c"))
+  map.get(map1, d)
+  |> should.equal(Ok("d"))
+  map.insert(map1, a2, "a2")
+  |> map.get(a)
+  |> should.equal(Ok("a2"))
+  map.insert(map1, a3, "a3")
+  |> map.get(a)
+  |> should.equal(Ok("a3"))
+}