`TestMarshalJSON` doesn't test the function it describes

[rootulp]

Context

rsmt2d/extendeddatasquare_test.go

Lines 89 to 112 in bb5e119

	func TestMarshalJSON(t *testing.T) {
	codec := NewLeoRSCodec()
	result, err := ComputeExtendedDataSquare([][]byte{
	ones, twos,
	threes, fours,
	}, codec, NewDefaultTree)
	if err != nil {
	panic(err)
	}
	edsBytes, err := json.Marshal(result)
	if err != nil {
	t.Errorf("failed to marshal EDS: %v", err)
	}
	var eds ExtendedDataSquare
	err = json.Unmarshal(edsBytes, &eds)
	if err != nil {
	t.Errorf("failed to marshal EDS: %v", err)
	}
	if !reflect.DeepEqual(result.squareRow, eds.squareRow) {
	t.Errorf("eds not equal after json marshal/unmarshal")
	}
	}

Problem

This test should be testing the behavior of MarshalJSON but it never invokes MarshalJSON.

Proposal

Update the test to invoke the function MarshalJSON

rsmt2d/extendeddatasquare.go

Lines 22 to 32 in bb5e119

	func (eds *ExtendedDataSquare) MarshalJSON() ([]byte, error) {
	return json.Marshal(&struct {
	DataSquare [][]byte `json:"data_square"`
	Codec string `json:"codec"`
	Tree string `json:"tree"`
	}{
	DataSquare: eds.dataSquare.Flattened(),
	Codec: eds.codec.Name(),
	Tree: eds.treeName,
	})
	}