Finish findScheduledChange method

internal/client/consensus/grandpa/warp_sync.go

@@ -312,8 +312,22 @@ func findScheduledChange(
 		}
 
 		switch val := digestValue.(type) {
-		case types.GrandpaScheduledChange:
-			return &val, nil
+		case types.ConsensusDigest:
+			consensusDigest := types.GrandpaConsensusDigest{}
+			if val.ConsensusEngineID == types.GrandpaEngineID {
+				err := scale.Unmarshal(val.Data, &consensusDigest)
+				if err != nil {
+					return nil, err
+				}
+
+				scheduledChange, err := consensusDigest.Value()
+				if err != nil {
+					return nil, err
+				}
+
+				parsedScheduledChange, _ := scheduledChange.(types.GrandpaScheduledChange)
+				return &parsedScheduledChange, nil
+			}
 		}
 	}
 	return nil, nil

internal/client/consensus/grandpa/warp_sync_test.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/ChainSafe/gossamer/dot/types"
 	"github.com/ChainSafe/gossamer/lib/common"
+	"github.com/ChainSafe/gossamer/pkg/scale"
 	"github.com/stretchr/testify/assert"
 	"go.uber.org/mock/gomock"
 )
@@ -84,28 +85,43 @@ func TestGenerateWarpSyncProofOk(t *testing.T) {
 			parentHash = blockHeaders[blockNumber-2].Hash()
 		}
 
+		digest := &types.Digest{}
+
+		if blockNumber == 4 {
+			// Last block in a set must contain a grandpa scheduled change
+			// So we create an empty one just to pass the nil check
+			scheduledChange := createGRANDPAConsensusDigest(t, types.GrandpaScheduledChange{
+				Auths: []types.GrandpaAuthoritiesRaw{},
+				Delay: 2,
+			})
+			consensuDigest := []types.ConsensusDigest{
+				scheduledChange,
+			}
+			digest.Add(consensuDigest)
+		}
+
 		header = types.NewHeader(
 			parentHash,
 			common.Hash{byte(blockNumber)},
 			common.Hash{byte(blockNumber)},
 			blockNumber,
-			types.Digest{},
+			*digest,
 		)
 
-		blockHeaders = append(blockHeaders, header)
-
-		// Mock block state responses
-		blockStateMock.EXPECT().GetHeader(header.Hash()).Return(header, nil).AnyTimes()
-		blockStateMock.EXPECT().GetHeaderByNumber(blockNumber).Return(header, nil).AnyTimes()
-
 		// authorities set changes happens only in block 5
 		if blockNumber < 5 {
-			grandpaStateMock.EXPECT().GetAuthoritiesChangesFromBlock(blockNumber).Return([]uint{5}, nil).AnyTimes()
+			grandpaStateMock.EXPECT().GetAuthoritiesChangesFromBlock(blockNumber).Return([]uint{4}, nil).AnyTimes()
 		} else if blockNumber == 5 {
 			blockStateMock.EXPECT().GetJustification(header.Hash()).Return(encodedJustification1, nil).AnyTimes()
 		} else {
 			grandpaStateMock.EXPECT().GetAuthoritiesChangesFromBlock(blockNumber).Return([]uint{}, nil).AnyTimes()
 		}
+
+		blockHeaders = append(blockHeaders, header)
+
+		// Mock block state responses
+		blockStateMock.EXPECT().GetHeader(header.Hash()).Return(header, nil).AnyTimes()
+		blockStateMock.EXPECT().GetHeaderByNumber(blockNumber).Return(header, nil).AnyTimes()
 	}
 
 	blockStateMock.EXPECT().GetHighestFinalisedHeader().Return(blockHeaders[len(blockHeaders)-1], nil).AnyTimes()
@@ -124,3 +140,43 @@ func TestGenerateWarpSyncProofOk(t *testing.T) {
 	}
 	assert.Equal(t, expectedProof, proof)
 }
+
+func TestFindScheduledChange(t *testing.T) {
+	t.Parallel()
+
+	scheduledChange := createGRANDPAConsensusDigest(t, types.GrandpaScheduledChange{
+		Auths: []types.GrandpaAuthoritiesRaw{},
+		Delay: 2,
+	})
+
+	digest := types.NewDigest()
+	digestAddArgs := make([]any, 1)
+	digestAddArgs[0] = types.ConsensusDigest(scheduledChange)
+	digest.Add(digestAddArgs...)
+
+	blockHeader := &types.Header{
+		ParentHash: common.Hash{0x00},
+		Number:     1,
+		Digest:     digest,
+	}
+
+	// Find scheduled change in block header
+	scheduledChangeDigest, err := findScheduledChange(*blockHeader)
+	assert.NoError(t, err)
+	assert.NotNil(t, scheduledChangeDigest)
+}
+
+func createGRANDPAConsensusDigest(t *testing.T, digestData any) types.ConsensusDigest {
+	t.Helper()
+
+	grandpaConsensusDigest := types.NewGrandpaConsensusDigest()
+	assert.NoError(t, grandpaConsensusDigest.SetValue(digestData))
+
+	marshaledData, err := scale.Marshal(grandpaConsensusDigest)
+	assert.NoError(t, err)
+
+	return types.ConsensusDigest{
+		ConsensusEngineID: types.GrandpaEngineID,
+		Data:              marshaledData,
+	}
+}