Provide UnmarshalJSON() for common.uint160

[omani]

fixes error json: cannot unmarshal string into Go struct field Account.ProgramHash of type common.Uint160 in case nkn.Account struct is to be unmarshalled.

[yilunzhang]

This will not update f. You need to change
func (f Uint160)
to
func (f *Uint160)
then change f, err = to temp, err :=,
and finally call f.SetBytes(temp.ToArray()) to update f.

[yilunzhang]

FYI I asked ChatGPT to write a unit test for this. This is the prompt I used:

Write unit tests for the following json marshal/unmarshal implementations:

 func (f Uint160) MarshalJSON() ([]byte, error) {
	str, err := f.ToAddress()
 	return []byte("\"" + str + "\""), err
 }

 func (f Uint160) UnmarshalJSON(in []byte) (err error) {
 	if len(in) < 2 {
 		return errors.New("[Common]: Uint160UnmarshalJSON err, len < 2")
 	}
 	f, err = ToScriptHash(string(in[1 : len(in)-1]))
 	return
 }

Results I got:

package yourpackage

import (
	"testing"
	"errors"
)

func TestMarshalJSON(t *testing.T) {
	// Create instance of Uint160
	f := new(Uint160)
	
	// Expected value after Marshalling
	expected := []byte("\"expectedValue\"")

	bytes, err := f.MarshalJSON()
	if err != nil {
		t.Fatalf("Unexpected error: %v", err)
	}

	if !bytesEqual(bytes, expected) {
		t.Fatalf("Expected %v, got %v", expected, bytes)
	}

	// TODO: If possible, create a scenario where ToAddress returns an error
	// and verify that MarshalJSON also returns this error.
}

func TestUnmarshalJSON(t *testing.T) {
	// Input for unmarshalling
	input := []byte("\"validInput\"")

	f := new(Uint160)
	err := f.UnmarshalJSON(input)
	if err != nil {
		t.Fatalf("Unexpected error: %v", err)
	}

	// TODO: Verify that f has been updated correctly

	input = []byte("\"a\"")
	err = f.UnmarshalJSON(input)
	if err == nil || err.Error() != "[Common]: Uint160UnmarshalJSON err, len < 2" {
		t.Fatalf("Expected error, got: %v", err)
	}

	// TODO: If possible, create a scenario where ToScriptHash returns an error
	// and verify that UnmarshalJSON also returns this error.
}

func bytesEqual(a, b []byte) bool {
	if len(a) != len(b) {
		return false
	}
	for i, v := range a {
		if v != b[i] {
			return false
		}
	}
	return true
}

[omani]

Ive included the unit tests.

regarding...

// TODO: If possible, create a scenario where ToAddress returns an error
// and verify that MarshalJSON also returns this error.

I dont know how to do this since SetBytes() prevents us from ever having a wrong address. it will get filled with zeros and a malformed version will always result in address NKNBV71h5oUBjknMHPikPU7nraw9KtksWjtB with no error.

[yilunzhang]

I dont know how to do this since SetBytes() prevents us from ever having a wrong address. it will get filled with zeros and a malformed version will always result in address NKNBV71h5oUBjknMHPikPU7nraw9KtksWjtB with no error.

Don't worry, the comments are auto generated by ChatGPT too, not all of them apply to our case.

[yilunzhang]

Looks good to me