[#42] Add ResolveContractHash method

Signed-off-by: Pavel Pogodaev <p.pogodaev@yadro.com>

ns/nns_test.go

@@ -154,3 +154,86 @@ func TestNNS_ResolveContainerDomain(t *testing.T) {
 		require.Equal(t, id, res)
 	})
 }
+
+func TestNNS_ResolveContractHash(t *testing.T) {
+	var testContainerDomain container.Domain
+	testContainerDomain.SetName("some_container")
+
+	var nnsContract util.Uint160
+
+	rand.Read(nnsContract[:])
+
+	testC := &testNeoClient{
+		t:                t,
+		expectedContract: nnsContract,
+	}
+
+	n := NNS{
+		nnsContract: nnsContract,
+		invoker:     testC,
+	}
+
+	t.Run("invocation failure", func(t *testing.T) {
+		err1 := errors.New("invoke err")
+		testC.err = err1
+
+		_, err2 := n.ResolveContractHash(testContainerDomain)
+		require.ErrorIs(t, err2, err1)
+	})
+
+	testC.err = nil
+
+	t.Run("fault exception", func(t *testing.T) {
+		_, err := n.ResolveContractHash(testContainerDomain)
+		require.Error(t, err)
+	})
+
+	testC.res.State = vmstate.Halt.String()
+
+	t.Run("empty stack", func(t *testing.T) {
+		_, err := n.ResolveContractHash(testContainerDomain)
+		require.Error(t, err)
+	})
+
+	testC.res.Stack = make([]stackitem.Item, 1)
+
+	t.Run("non-array last stack item", func(t *testing.T) {
+		testC.res.Stack[0] = stackitem.NewBigInteger(big.NewInt(11))
+
+		_, err := n.ResolveContractHash(testContainerDomain)
+		require.Error(t, err)
+	})
+
+	t.Run("null array", func(t *testing.T) {
+		testC.res.Stack[0] = stackitem.Null{}
+
+		_, err := n.ResolveContractHash(testContainerDomain)
+		require.ErrorIs(t, err, errNotFound)
+	})
+
+	t.Run("array stack item with non-slice value", func(t *testing.T) {
+		testC.res.Stack[0] = brokenArrayStackItem{}
+
+		_, err := n.ResolveContractHash(testContainerDomain)
+		require.Error(t, err)
+	})
+
+	arr := make([]stackitem.Item, 2)
+	testC.res.Stack[0] = stackitem.NewArray(arr)
+
+	t.Run("non-bytes array element", func(t *testing.T) {
+		arr[0] = stackitem.NewArray(nil)
+
+		_, err := n.ResolveContractHash(testContainerDomain)
+		require.Error(t, err)
+	})
+
+	arr[0] = stackitem.NewByteArray([]byte("some byte array 1"))
+
+	t.Run("non-container array elements", func(t *testing.T) {
+		arr[1] = stackitem.NewByteArray([]byte("some byte array 2"))
+
+		_, err := n.ResolveContractHash(testContainerDomain)
+		require.Error(t, err)
+	})
+}