simple updated to make isempty workable for each data structures

src/PowerNetworkMatrix.jl

@@ -303,7 +303,7 @@ function Base.show_nd(
     end
 end
 
-function Base.show(io::IO, ::MIME{Symbol("text/plain")}, array::PowerNetworkMatrix)
+function Base.show(io::IO, array::PowerNetworkMatrix)
     summary(io, array)
     isempty(array) && return
     println(io, ":")

src/virtual_lodf_calculations.jl

@@ -54,6 +54,14 @@ struct VirtualLODF{Ax, L <: NTuple{2, Dict}} <: PowerNetworkMatrix{Float64}
     tol::Base.RefValue{Float64}
 end
 
+function Base.show(io::IO, ::MIME{Symbol("text/plain")}, array::VirtualLODF)
+    summary(io, array)
+    isempty(array) && return
+    println(io, ":")
+    Base.print_array(io, array)
+    return
+end
+
 function _get_PTDF_A_diag(
     K::KLU.KLUFactorization{Float64, Int},
     BA::SparseArrays.SparseMatrixCSC{Float64, Int},

src/virtual_ptdf_calculations.jl

@@ -57,6 +57,14 @@ struct VirtualPTDF{Ax, L <: NTuple{2, Dict}} <: PowerNetworkMatrix{Float64}
     tol::Base.RefValue{Float64}
 end
 
+function Base.show(io::IO, ::MIME{Symbol("text/plain")}, array::VirtualPTDF)
+    summary(io, array)
+    isempty(array) && return
+    println(io, ":")
+    Base.print_array(io, array)
+    return
+end
+
 """
 Builds the PTDF matrix from a group of branches and buses. The return is a
 PTDF array indexed with the branch numbers.

test/test_BA_ABA_matrix.jl

@@ -79,3 +79,24 @@ end
     end
     @test test_val
 end
+
+@testset "Test show for A, BA and ABA matrix" begin
+    sys = PSB.build_system(PSB.PSITestSystems, "c_sys5")
+
+    a = IncidenceMatrix(sys)
+    ba = BA_Matrix(sys)
+    aba = ABA_Matrix(sys)
+
+    for mat in [a, ba, aba]
+        test_value = false
+        try
+            show(@eval a)
+            test_value = true
+        catch err
+            if err isa Exception
+                test_value = false
+            end
+        end
+        @test test_value
+    end
+end

test/test_virtual_lodf.jl

@@ -103,9 +103,11 @@ end
 @testset "Test Virtual LODF auxiliary functions" begin
     sys = PSB.build_system(PSB.PSITestSystems, "c_sys5")
 
+    # test isempty when VirtualLODF is created (cache must be empty)
     vlodf = VirtualLODF(sys)
     @test isempty(vlodf) == true
 
+    # test eachindex and axes
     @test length(eachindex(vlodf)) ==
           length(axes(vlodf)[1]) * length(axes(vlodf)[2])
 
@@ -119,4 +121,16 @@ end
         end
     end
     @test test_value
+
+    # test show
+    test_value = false
+    try
+        show(vlodf)
+        test_value = true
+    catch err
+        if err isa Exception
+            test_value = false
+        end
+    end
+    @test test_value
 end

test/test_virtual_ptdf.jl

@@ -177,4 +177,16 @@ end
     @test setdiff(PNM.get_branch_ax(vptdf), PSY.get_name.(PNM.get_ac_branches(sys))) ==
           String[]
     @test setdiff(PNM.get_bus_ax(vptdf), PSY.get_number.(PNM.get_buses(sys))) == String[]
+
+    # test show
+    test_value = false
+    try
+        show(vptdf)
+        test_value = true
+    catch err
+        if err isa Exception
+            test_value = false
+        end
+    end
+    @test test_value
 end