test: count difficulty

pkg/relayer/protocol/difficulty_test.go

@@ -0,0 +1,56 @@
+package protocol_test
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/pokt-network/poktroll/pkg/relayer/protocol"
+)
+
+func TestCountDifficultyBits(t *testing.T) {
+	tests := []struct {
+		bz         []byte
+		difficulty int
+	}{
+		{
+			bz:         []byte{0b11111111, 255, 255, 255},
+			difficulty: 0,
+		},
+		{
+			bz:         []byte{0b01111111, 255, 255, 255},
+			difficulty: 1,
+		},
+		{
+			bz:         []byte{0, 255, 255, 255},
+			difficulty: 8,
+		},
+		{
+			bz:         []byte{0, 0b01111111, 255, 255},
+			difficulty: 9,
+		},
+		{
+			bz:         []byte{0, 0b00111111, 255, 255},
+			difficulty: 10,
+		},
+		{
+			bz:         []byte{0, 0, 255, 255},
+			difficulty: 16,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(fmt.Sprintf("difficulty_%d", tt.difficulty), func(t *testing.T) {
+			actualDifficulty, err := protocol.CountDifficultyBits(tt.bz)
+			require.NoError(t, err)
+			require.Equal(t, tt.difficulty, actualDifficulty)
+		})
+	}
+}
+
+func TestCountDifficultyBits_Error(t *testing.T) {
+	_, err := protocol.CountDifficultyBits([]byte{0, 0, 0, 0})
+	require.ErrorIs(t, err, protocol.ErrDifficulty)
+	require.ErrorContains(t, err, "difficulty matches bytes length")
+}