Fixed string attribute reading, added a unittest for that

Author: vfonov

src/minc2_io.jl

@@ -596,7 +596,7 @@ function read_attribute(h::VolumeHandle,
     # TODO: make sure it's a good assumption
     if attr_type[] == minc2_simple.MINC2_STRING 
         # remove trailing 0?
-        _buf = Vector{UInt8}(undef,attr_length[]+1) 
+        _buf = Vector{UInt8}(undef,attr_length[]) 
         @minc2_check minc2_simple.minc2_read_attribute(h.x[], group, attribute, _buf, attr_length[])
         return String(_buf)
     elseif attr_type[] == minc2_simple.MINC2_FLOAT

test/input/t1_z+_byte_cor.history.txt

@@ -0,0 +1 @@
+vfonov:gonzalo:2022.03.24.14.04.08:1124386:1

test/input/t1_z+_byte_cor.ident.txt

@@ -12,9 +12,14 @@ using Tables
 
     @testset "Reading attributes" begin
         h=Minc2.open_minc_file("input/t1_z+_byte_cor.mnc")
-        @test length(Minc2.read_attribute(h,"","history")) == 777
-        @test length(Minc2.read_attribute(h,"","ident")) == 45
-        ### TODO: add tests for more attributes
+        @test Minc2.read_attribute(h,"","history") == String(read("input/t1_z+_byte_cor.history.txt"))
+        @test Minc2.read_attribute(h,"","ident") == String(read("input/t1_z+_byte_cor.ident.txt"))
+        Minc2.close_minc_file(h)
+    end
+
+    @testset "Reading attributes 2" begin
+        h=Minc2.open_minc_file("input/3DDoubleImage_double_byte.mnc")
+        @test Minc2.read_attribute(h,"acquisition","StdString") == "Test std::string\0"
         Minc2.close_minc_file(h)
     end