add tests for left and right units

Author: borisdevos

test/test_A4.jl

@@ -1,5 +1,5 @@
 using MultiTensorKit
-using TensorKitSectors
+using TensorKitSectors, TensorKit
 using Test, TestExtras
 
 I = A4Object
@@ -75,3 +75,42 @@ end
     @test dual(s) == A4Object(j, i, MultiTensorKit._get_dual_cache(I)[2][i, j][s.label])
     @test dual(dual(s)) == s
 end
+
+@testset "A4 Category ($i, $j) left and right units" for i in 1:12, j in 1:12
+    Cij_obs = A4Object.(i, j, MultiTensorKit._get_dual_cache(I)[2][i, j])
+
+    s = rand(Cij_obs, 1)[1]
+    sp = Vect[A4Object](s => 1)
+    W = sp ← sp
+    for T in (Float32, ComplexF64)
+        t = @constinferred rand(T, W)
+
+        for a in 1:2
+            tl = @constinferred insertleftunit(t, Val(a))
+            @test numind(tl) == numind(t) + 1
+            @test space(tl) == insertleftunit(space(t), a)
+            @test scalartype(tl) === T
+            @test t.data === tl.data
+            @test @constinferred(removeunit(tl, $(a))) == t
+
+            tr = @constinferred insertrightunit(t, Val(a))
+            @test numind(tr) == numind(t) + 1
+            @test space(tr) == insertrightunit(space(t), a)
+            @test scalartype(tr) === T
+            @test t.data === tr.data
+            @test @constinferred(removeunit(tr, $(a + 1))) == t
+        end
+
+        @test_throws ErrorException insertleftunit(t) # default should error here
+        @test insertrightunit(t) isa TensorMap
+        @test_throws ErrorException insertleftunit(t, numind(t) + 1) # same as default
+        @test_throws ErrorException insertrightunit(t, numind(t) + 1) # not same as default
+
+        t2 = @constinferred insertrightunit(t; copy=true)
+        @test t.data !== t2.data
+        for (c, b) in blocks(t)
+            @test b == block(t2, c)
+        end
+        @test @constinferred(removeunit(t2, $(numind(t2)))) == t
+    end
+end