fix: resolves #2733

.changeset/pretty-brooms-pull.md

@@ -0,0 +1,5 @@
+---
+"viem": patch
+---
+
+Fixed issue where \`watchBlock\` would not respect the \`emitOnBegin\` property for WebSocket Transports.

src/actions/public/watchBlocks.test.ts

@@ -623,6 +623,8 @@ describe('poll', () => {
  })
  expect(error).toMatchInlineSnapshot('[Error: foo]')
  unwatch()
+
+ vi.restoreAllMocks()
  })
  })
 })
@@ -654,6 +656,27 @@ describe('subscribe', () => {
  expect(typeof blocks[0].number).toBe('bigint')
  })
 
+ describe('emitOnBegin', () => {
+ test('watches for new blocks', async () => {
+ const blocks: OnBlockParameter[] = []
+ const unwatch = watchBlocks(webSocketClient, {
+ emitOnBegin: true,
+ onBlock: (block) => blocks.push(block),
+ })
+ await wait(800)
+ await mine(client, { blocks: 1 })
+ await wait(200)
+ await mine(client, { blocks: 1 })
+ await wait(200)
+ await mine(client, { blocks: 1 })
+ await wait(200)
+ await mine(client, { blocks: 1 })
+ await wait(200)
+ unwatch()
+ expect(blocks.length).toBe(5)
+ })
+ })
+
  describe('behavior', () => {
  test('does not emit when no new incoming blocks', async () => {
  const blocks: OnBlockParameter[] = []

src/actions/public/watchBlocks.ts

@@ -202,9 +202,26 @@ export function watchBlocks<
 
  const subscribeBlocks = () => {
  let active = true
+ let emitFetched = true
  let unsubscribe = () => (active = false)
  ;(async () => {
  try {
+ if (emitOnBegin) {
+ getAction(
+ client,
+ getBlock,
+ 'getBlock',
+ )({
+ blockTag,
+ includeTransactions,
+ }).then((block) => {
+ if (!active) return
+ if (!emitFetched) return
+ onBlock(block as any, undefined)
+ emitFetched = false
+ })
+ }
+
  const transport = (() => {
  if (client.transport.type === 'fallback') {
  const transport = client.transport.transports.find(
@@ -225,6 +242,7 @@ export function watchBlocks<
  client.chain?.formatters?.block?.format || formatBlock
  const block = format(data.result)
  onBlock(block, prevBlock as any)
+ emitFetched = false
  prevBlock = block
  },
  onError(error: Error) {