Add tests for reading legend-testdata histograms

test/histograms/histogram_io.jl

@@ -1,5 +1,7 @@
 using StatsBase
-
+using LegendHDF5IO
+using LegendTestData
+using Test
 using LegendHDF5IO: _nt_to_histogram, _histogram_to_nt
 
 @testset "Histogram <-> NamedTuple" begin
@@ -9,4 +11,17 @@ using LegendHDF5IO: _nt_to_histogram, _histogram_to_nt
     @test _nt_to_histogram(_histogram_to_nt(h)) == h
     h = fit(Histogram, (rand(10), rand(10)), (0:0.2:1, Float64[0, 0.5, 1]))
     @test _nt_to_histogram(_histogram_to_nt(h)) == h
+end
+
+@testset "Histogram IO" begin 
+    fn = joinpath(legend_test_data_path(), "data", "lh5", "lgdo-histograms.lh5")
+    lh5open(fn) do h5
+        names = keys(h5)
+        for name in names
+            @testset "$name" begin
+                h = @test_nowarn h5[name]
+                @test h isa Histogram
+            end
+        end
+    end
 end