Avoid using unexported constants in tests

This commit:
- adds new function targetSlabSize() in settings.go
- exports targetSlabSize() to TargetSlabSize() in export_test.go
  for testing
- modifies tests to use exported function instead of unexported
constants targetThreshold.

array_test.go

@@ -5028,7 +5028,7 @@ func TestArrayMaxInlineElement(t *testing.T) {
 	// Size of root data slab with two elements of max inlined size is target slab size minus
 	// slab id size (next slab id is omitted in root slab), and minus 1 byte
 	// (for rounding when computing max inline array element size).
-	require.Equal(t, targetThreshold-SlabIDLength-1, uint64(array.root.Header().size))
+	require.Equal(t, TargetSlabSize()-SlabIDLength-1, uint64(array.root.Header().size))
 
 	testArray(t, storage, typeInfo, address, array, values, false)
 }

export_test.go

@@ -26,3 +26,8 @@ var (
 	GetCBOREncMode = (*PersistentSlabStorage).getCBOREncMode
 	GetCBORDecMode = (*PersistentSlabStorage).getCBORDecMode
 )
+
+// Exported function of slab size settings for testing.
+var (
+	TargetSlabSize = targetSlabSize
+)

map_test.go

@@ -14339,7 +14339,7 @@ func TestMapMaxInlineElement(t *testing.T) {
 	// Size of root data slab with two elements (key+value pairs) of
 	// max inlined size is target slab size minus
 	// slab id size (next slab id is omitted in root slab)
-	require.Equal(t, targetThreshold-SlabIDLength, uint64(m.root.Header().size))
+	require.Equal(t, TargetSlabSize()-SlabIDLength, uint64(m.root.Header().size))
 
 	testMap(t, storage, typeInfo, address, m, keyValues, nil, false)
 }

settings.go

@@ -86,3 +86,7 @@ func MaxInlineMapKeySize() uint64 {
 func maxInlineMapValueSize(keySize uint64) uint64 {
 	return maxInlineMapElementSize - keySize - singleElementPrefixSize
 }
+
+func targetSlabSize() uint64 {
+	return targetThreshold
+}