From 781397b0d73d97c651b4b4496d5c300835861056 Mon Sep 17 00:00:00 2001
From: Bodigrim <andrew.lelechenko@gmail.com>
Date: Mon, 25 Sep 2023 20:09:23 +0100
Subject: [PATCH] Test IntervalSet: {0} V complement {0}

---
 test/TestIntervalSet.hs | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/test/TestIntervalSet.hs b/test/TestIntervalSet.hs
index c4fb131..d71c441 100644
--- a/test/TestIntervalSet.hs
+++ b/test/TestIntervalSet.hs
@@ -110,6 +110,22 @@ case_insert_connected =
   IntervalSet.insert (1 <=..< 2 :: Interval Rational) (IntervalSet.fromList [ 0 <=..< 1, 2 <=..< 3 ])
   @?= IntervalSet.singleton (0 <=..< 3)
 
+case_insert_zero =
+  IntervalSet.insert zero (IntervalSet.complement $ IntervalSet.singleton zero) @?= IntervalSet.whole
+  where
+    zero :: Interval Rational
+    zero = 0 <=..<= 0
+
+case_insert_zero_negative =
+  IntervalSet.insert zero negative @?= nonPositive
+  where
+    zero :: Interval Rational
+    zero = 0 <=..<= 0
+    negative :: IntervalSet Rational
+    negative = IntervalSet.singleton $ NegInf <..< 0
+    nonPositive :: IntervalSet Rational
+    nonPositive = IntervalSet.singleton $ NegInf <..<= 0
+
 {--------------------------------------------------------------------
   delete
 --------------------------------------------------------------------}