diff --git a/src/include/array/array_base.cc.h b/src/include/array/array_base.cc.h
index dcc1779..b8185f6 100644
--- a/src/include/array/array_base.cc.h
+++ b/src/include/array/array_base.cc.h
@@ -234,6 +234,7 @@ namespace CNORXZ
     template <typename I, typename M>
     T& ArrayBase<T>::operator[](const IndexInterface<I,M>& i)
     {
+	// TODO: if format of i is non-trivial, use that format without check (checks only in at()!)
 	if(this->formatIsTrivial()){
 	    return data()[i.lex()];
 	}
diff --git a/src/tests/CMakeLists.txt b/src/tests/CMakeLists.txt
index 773b306..5a5f8d5 100644
--- a/src/tests/CMakeLists.txt
+++ b/src/tests/CMakeLists.txt
@@ -27,6 +27,11 @@ add_dependencies(mautest cnorxz)
 target_link_libraries(mautest ${GTEST_BOTH_LIBRARIES} ${CMAKE_THREAD_LIBS_INIT} cnorxz test_lib)
 add_test(NAME mautest COMMAND mautest)
 
+add_executable(lutest l_unit_test.cc)
+add_dependencies(lutest cnorxz)
+target_link_libraries(lutest ${GTEST_BOTH_LIBRARIES} ${CMAKE_THREAD_LIBS_INIT} cnorxz test_lib)
+add_test(NAME lutest COMMAND lutest)
+
 add_executable(oputest operation_unit_test.cc)
 add_dependencies(oputest cnorxz)
 target_link_libraries(oputest ${GTEST_BOTH_LIBRARIES} ${CMAKE_THREAD_LIBS_INIT} cnorxz test_lib)
diff --git a/src/tests/l_unit_test.cc b/src/tests/l_unit_test.cc
new file mode 100644
index 0000000..a157ab2
--- /dev/null
+++ b/src/tests/l_unit_test.cc
@@ -0,0 +1,77 @@
+// -*- C++ -*-
+/**
+   
+   @file tests/l_unit_test.cc
+   @brief MArray unit tests.
+
+   Copyright (c) 2024 Christian Zimmermann. All rights reserved.
+   Mail: chizeta@f3l.de
+   
+**/
+
+#include <cstdlib>
+#include <iostream>
+
+#include "gtest/gtest.h"
+
+#include "cnorxz.h"
+#include "test_numbers.h"
+
+namespace
+{
+    using namespace CNORXZ;
+    using Test::Numbers;
+
+    class L_Test : public ::testing::Test
+    {
+    protected:
+	
+	L_Test()
+	{
+	    auto a4 = Arr<SizeT,4> { 0,1,2,3 }; 
+	    auto a3 = Arr<SizeT,3> { 0,1,2 }; 
+	    mSpinR = std::dynamic_pointer_cast<SRange<SizeT,4>> ( SRangeFactory<SizeT,4>(a4).create() );
+	    mColorR = std::dynamic_pointer_cast<SRange<SizeT,3>> ( SRangeFactory<SizeT,3>(a3).create() );
+	    mSpatialR = std::dynamic_pointer_cast<CRange> ( CRangeFactory(8).create() );
+	    mTemporalR = std::dynamic_pointer_cast<CRange> ( CRangeFactory(24).create() );
+	    mLocSR = std::dynamic_pointer_cast<CRange> ( CRangeFactory(4).create() );
+	    mLocTR = std::dynamic_pointer_cast<CRange> ( CRangeFactory(8).create() );
+	    mRaSR = std::dynamic_pointer_cast<CRange> ( CRangeFactory(2).create() );
+	    mRaTR = std::dynamic_pointer_cast<CRange> ( CRangeFactory(3).create() );
+	    mData = MArray<Double>(yrange({mRaTR,mRaSR,mRaSR,mRaSR,mLocTR,mLocSR,mLocSR,mLocSR,mSpinR,mColorR,mSpinR,mColorR}));
+	    mDataFormat = mData.begin().format();
+	    auto vf = mDataFormat.all();
+	    vf[0] = mDataFormat[0];
+	    vf[1] = mDataFormat[4];
+	    vf[2] = mDataFormat[1];
+	    vf[3] = mDataFormat[5];
+	    vf[4] = mDataFormat[2];
+	    vf[5] = mDataFormat[6];
+	    vf[6] = mDataFormat[3];
+	    vf[7] = mDataFormat[7];
+	    mViewFormat = YFormat(vf);
+	    mView = Slice<Double>(yrange({mRaTR,mLocTR,mRaSR,mLocSR,mRaSR,mLocSR,mRaSR,mLocSR,mSpinR,mColorR,mSpinR,mColorR}), &mData, mViewFormat, 0);
+	}
+	
+	Sptr<SRange<SizeT,4>> mSpinR;
+	Sptr<SRange<SizeT,3>> mColorR;
+	Sptr<CRange> mSpatialR;
+	Sptr<CRange> mTemporalR;
+	Sptr<CRange> mLocSR;
+	Sptr<CRange> mLocTR;
+	Sptr<CRange> mRaSR;
+	Sptr<CRange> mRaTR;
+
+	MArray<Double> mData;
+	Slice<Double> mView;
+	YFormat mDataFormat;
+	YFormat mViewFormat;
+    };
+
+    TEST_F(L_Test, Basic)
+    {
+	EXPECT_EQ(mData.size(), mView.size());
+	VCHECK(mData.size());
+    }
+    
+}