From bd6ad12be497b5da05a82d7bac44fcbe72a003a5 Mon Sep 17 00:00:00 2001
From: schillic <git@christianschilling.net>
Date: Tue, 28 May 2024 11:33:06 +0200
Subject: [PATCH] revise and test convert to Interval

---
 src/convert.jl        | 17 ++++++-----------
 test/Sets/Interval.jl |  8 +++++++-
 2 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/src/convert.jl b/src/convert.jl
index 7b9448da96..f182726e71 100644
--- a/src/convert.jl
+++ b/src/convert.jl
@@ -412,14 +412,7 @@ Interval{Float64}([0, 1])
 ```
 """
 function convert(::Type{Interval}, X::LazySet)
-    @assert dim(X) == 1 "cannot convert a $(dim(X))-dimensional set to an " *
-                        "`Interval`"
-    if !isconvextype(typeof(X))
-        error("this implementation requires a convex set")
-    end
-
-    l, h = extrema(X, 1)
-    return Interval(l, h)
+    return Interval(convert(IA.Interval, X))
 end
 
 """
@@ -619,9 +612,11 @@ Convert a convex set to an `Interval` from `IntervalArithmetic`.
 An `IntervalArithmetic.Interval`.
 """
 function convert(::Type{IA.Interval}, X::LazySet)
-    @assert dim(X) == 1 "cannot convert a $(dim(X))-dimensional set to an " *
-                        "interval"
-    return convert(Interval, X).dat
+    @assert dim(X) == 1 "cannot convert a $(dim(X))-dimensional set to an `Interval`"
+    @assert isconvextype(typeof(X)) "cannot convert a non-convex set to an `Interval`"
+
+    l, h = extrema(X, 1)
+    return IA.interval(l, h)
 end
 
 """
diff --git a/test/Sets/Interval.jl b/test/Sets/Interval.jl
index 757e7917f6..01392b5bff 100644
--- a/test/Sets/Interval.jl
+++ b/test/Sets/Interval.jl
@@ -186,9 +186,15 @@ for N in [Float64, Float32, Rational{Int}]
     M = hcat(N[2])
     B = convert(Interval, M * H)
     @test B isa Interval && low(B) == [N(-1)] && high(B) == [N(1)]
-    # conversion to an IntervalArithmetic.Interval
+    # conversion to and from IntervalArithmetic.Interval
     B2 = convert(IA.Interval, M * H)
     @test B2 == B.dat
+    B3 = convert(Interval, B2)
+    @test B3 == B
+    # conversion from a non-convex set fails
+    U = UnionSet(Interval(1, 2), Interval(3, 4))
+    @test_throws AssertionError convert(Interval, U)
+    @test_throws AssertionError convert(IA.Interval, U)
 
     # set difference
     A = Interval(N(5), N(8))