feat(testda): add header support with GetHeaderByHeight method

test/testda/dummy.go

@@ -15,13 +15,27 @@ const (
 	DefaultMaxBlobSize = 2 * 1024 * 1024
 )
 
+// Header contains DA layer header information for a given height.
+// This mirrors the structure used by real DA clients like Celestia.
+type Header struct {
+	Height    uint64
+	Timestamp time.Time
+}
+
+// Time returns the block time from the header.
+// This mirrors the jsonrpc.Header.Time() method.
+func (h *Header) Time() time.Time {
+	return h.Timestamp
+}
+
 // DummyDA is a test implementation of the DA client interface.
-// It supports blob storage, height simulation, and failure injection.
+// It supports blob storage, height simulation, failure injection, and header retrieval.
 type DummyDA struct {
 	mu         sync.Mutex
 	height     atomic.Uint64
 	maxBlobSz  uint64
 	blobs      map[uint64]map[string][][]byte // height -> namespace -> blobs
+	headers    map[uint64]*Header             // height -> header (with timestamp)
 	failSubmit atomic.Bool
 
 	tickerMu   sync.Mutex
@@ -50,6 +64,7 @@ func New(opts ...Option) *DummyDA {
 	d := &DummyDA{
 		maxBlobSz: DefaultMaxBlobSize,
 		blobs:     make(map[uint64]map[string][][]byte),
+		headers:   make(map[uint64]*Header),
 	}
 	for _, opt := range opts {
 		opt(d)
@@ -81,13 +96,21 @@ func (d *DummyDA) Submit(_ context.Context, data [][]byte, _ float64, namespace
 		blobSz += uint64(len(b))
 	}
 
+	now := time.Now()
 	d.mu.Lock()
 	height := d.height.Add(1)
 	if d.blobs[height] == nil {
 		d.blobs[height] = make(map[string][][]byte)
 	}
 	nsKey := string(namespace)
 	d.blobs[height][nsKey] = append(d.blobs[height][nsKey], data...)
+	// Store header with timestamp for this height
+	if d.headers[height] == nil {
+		d.headers[height] = &Header{
+			Height:    height,
+			Timestamp: now,
+		}
+	}
 	d.mu.Unlock()
 
 	return datypes.ResultSubmit{
@@ -96,7 +119,7 @@ func (d *DummyDA) Submit(_ context.Context, data [][]byte, _ float64, namespace
 			Height:         height,
 			BlobSize:       blobSz,
 			SubmittedCount: uint64(len(data)),
-			Timestamp:      time.Now(),
+			Timestamp:      now,
 		},
 	}
 }
@@ -109,6 +132,11 @@ func (d *DummyDA) Retrieve(_ context.Context, height uint64, namespace []byte) d
 	if byHeight != nil {
 		blobs = byHeight[string(namespace)]
 	}
+	// Get timestamp from header if available, otherwise use current time
+	var timestamp time.Time
+	if header := d.headers[height]; header != nil {
+		timestamp = header.Timestamp
+	}
 	d.mu.Unlock()
 
 	if len(blobs) == 0 {
@@ -117,7 +145,7 @@ func (d *DummyDA) Retrieve(_ context.Context, height uint64, namespace []byte) d
 				Code:      datypes.StatusNotFound,
 				Height:    height,
 				Message:   datypes.ErrBlobNotFound.Error(),
-				Timestamp: time.Now(),
+				Timestamp: timestamp,
 			},
 		}
 	}
@@ -128,7 +156,7 @@ func (d *DummyDA) Retrieve(_ context.Context, height uint64, namespace []byte) d
 			Code:      datypes.StatusSuccess,
 			Height:    height,
 			IDs:       ids,
-			Timestamp: time.Now(),
+			Timestamp: timestamp,
 		},
 		Data: blobs,
 	}
@@ -202,7 +230,16 @@ func (d *DummyDA) StartHeightTicker(interval time.Duration) func() {
 		for {
 			select {
 			case <-ticker.C:
-				d.height.Add(1)
+				now := time.Now()
+				height := d.height.Add(1)
+				d.mu.Lock()
+				if d.headers[height] == nil {
+					d.headers[height] = &Header{
+						Height:    height,
+						Timestamp: now,
+					}
+				}
+				d.mu.Unlock()
 			case <-stopCh:
 				return
 			}
@@ -219,11 +256,12 @@ func (d *DummyDA) StartHeightTicker(interval time.Duration) func() {
 	}
 }
 
-// Reset clears all stored blobs and resets the height.
+// Reset clears all stored blobs, headers, and resets the height.
 func (d *DummyDA) Reset() {
 	d.mu.Lock()
 	d.height.Store(0)
 	d.blobs = make(map[uint64]map[string][][]byte)
+	d.headers = make(map[uint64]*Header)
 	d.failSubmit.Store(false)
 	d.mu.Unlock()
 
@@ -234,3 +272,21 @@ func (d *DummyDA) Reset() {
 	}
 	d.tickerMu.Unlock()
 }
+
+// GetHeaderByHeight retrieves the header for the given DA height.
+// This mirrors the HeaderAPI.GetByHeight method from the real DA client.
+// Returns nil if no header exists for the given height.
+func (d *DummyDA) GetHeaderByHeight(_ context.Context, height uint64) (*Header, error) {
+	d.mu.Lock()
+	header := d.headers[height]
+	d.mu.Unlock()
+
+	if header == nil {
+		currentHeight := d.height.Load()
+		if height > currentHeight {
+			return nil, datypes.ErrHeightFromFuture
+		}
+		return nil, datypes.ErrBlobNotFound
+	}
+	return header, nil
+}