From 471e5c27936e1b8baab49cb510e9a9c9a5b6df2c Mon Sep 17 00:00:00 2001
From: Aayush Sabharwal <aayush.sabharwal@gmail.com>
Date: Wed, 9 Oct 2024 13:19:56 +0530
Subject: [PATCH] fix: fix unnecessary `oneunit` call in `get_unit`

---
 src/systems/unit_check.jl | 2 +-
 test/units.jl             | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/systems/unit_check.jl b/src/systems/unit_check.jl
index 5035a22b5e..d3a8db7b77 100644
--- a/src/systems/unit_check.jl
+++ b/src/systems/unit_check.jl
@@ -77,7 +77,7 @@ get_unit(x::SciMLBase.NullParameters) = unitless
 get_unit(op::typeof(instream), args) = get_unit(args[1])
 
 function get_unit(op, args) # Fallback
-    result = oneunit(op(get_unit.(args)...))
+    result = op(get_unit.(args)...)
     try
         get_unit(result)
     catch
diff --git a/test/units.jl b/test/units.jl
index ff0cd42ac3..e279166d62 100644
--- a/test/units.jl
+++ b/test/units.jl
@@ -240,3 +240,10 @@ sys = complete(sys)
 @test isequal(ModelingToolkit.getdefault(sys.pt.a), sys.v * sys.τ)
 @test ModelingToolkit.getdefault(sys.v) ≈ 2.0
 @test ModelingToolkit.getdefault(sys.τ) ≈ 3.0
+
+@testset "Issue#3017" begin
+    @constants c = 1 [unit = us"mol/nmol"]
+    @variables k(t) [unit = us"mol/nmol"]
+    @test ModelingToolkit.get_unit(c) == ModelingToolkit.get_unit(-c)
+    @test_nowarn NonlinearSystem([k ~ c], [k], []; name=:example)
+end